U.S. patent application number 10/490017 was filed with the patent office on 2005-04-14 for reinforcement material and reinforcement structure of structure and method of designing reinforcement material.
This patent application is currently assigned to STRUCTURAL QUALITY ASSURANCE, INC.. Invention is credited to Igarashi, Shunichi.
Application Number | 20050076596 10/490017 |
Document ID | / |
Family ID | 26345140 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050076596 |
Kind Code |
A1 |
Igarashi, Shunichi |
April 14, 2005 |
Reinforcement material and reinforcement structure of structure and
method of designing reinforcement material
Abstract
Disclosed is a reinforcing member, which comprises a woven body
formed by a weaving process, or a tape-shaped or sheet-shaped body,
having a high ductility and high bendability. The reinforcing
member is adapted to be installed on a surface of a structure
member or a boundary portion of the structure member, or inside a
structure member, to reinforce the structure member. The woven
body, or a tape-shaped or sheet-shaped body, has a Young's modulus
equal to or less than that of the structure member, and a tensile
fracture strain of 10% or more. The Young's modulus of the
reinforcing member is preferably in the range of 1/2 to 1/20, more
preferably 1/5 to 1/10, of that of the structure member.
Specifically, the Young's modulus of the woven body is preferably
in the range of 500 to 50000 MPa, more preferably 1000 to 10000
MPa. The present invention also provides a reinforced structure
using the above reinforcing member.
Inventors: |
Igarashi, Shunichi; (Tokyo,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
STRUCTURAL QUALITY ASSURANCE,
INC.
1-11-5 Kudankita, Chiyoda-ku
Tokyo
JP
102-8220
|
Family ID: |
26345140 |
Appl. No.: |
10/490017 |
Filed: |
March 19, 2004 |
PCT Filed: |
September 25, 2002 |
PCT NO: |
PCT/JP02/09838 |
Current U.S.
Class: |
52/514 ;
52/741.4 |
Current CPC
Class: |
E04G 2023/0255 20130101;
E04G 23/0218 20130101; E04G 23/0225 20130101; E04C 5/07 20130101;
E04C 5/04 20130101; E04G 2023/0251 20130101 |
Class at
Publication: |
052/514 ;
052/741.4 |
International
Class: |
E04G 023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2001 |
JP |
PCT JP01 08287 |
Mar 8, 2002 |
JP |
PCT JP02 02167 |
Claims
1-64. (canceled)
65. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members, having a high
bendability to fit an edge or edges of said member or members, and
to follow a deformation of said member or members without breaking
said member or members so as to maintain a reinforcement
effect.
66. The reinforcing member as defined in claim 65, which has a
bending deformation angle of 90-degree or more.
67. The reinforcing member as defined in claim 65, which has a
shear deformation angle of 2-degree or more.
68. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members, having a high
bendability and an elasticity, with a Young's modulus not greater
than that of said member or members to follow a deformation of said
member or members without breaking said member or members so as to
maintain a reinforcement effect.
69. The reinforcing member as defined in claim 68, wherein the
Young's modulus is to be a product specification value.
70. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members, wherein in said
reinforcing member a design size thereof is determined by the
product of a Young's modulus and thickness.
71. The reinforcing member as defined in claim 65, which is formed
by a weaving process.
72. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members having an
elasticity and a high ductility, with a tensile fracture strain
thereof greater than that of said member or members to follow a
deformation of said member or members without breaking said member
or members so as to maintain a reinforcement effect.
73. The reinforcing member as defined in claim 72, wherein the
tensile fracture strain is 10% or more.
74. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members, wherein in said
reinforcing member a tensile fracture strain is a product
specification value.
75. A reinforcing member to be installed on a member or members of
a structure to reinforce said member or members, said reinforcing
member having an elasticity and a high ductility, with a Young's
modulus in the range of 500 to 50,000 Mpa to follow a deformation
of said member or members without breaking said member or members
so as to maintain a reinforcement effect.
76. The reinforcing member as defined in claim 65, which comprises
a woven body being heat-set to allow a Young's modulus in a design
limit state to be greater.
77. The reinforcing member as defined in claim 65, which is made of
a rubber-based or resin-based elastic material.
78. A fixation material to be used for a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said fixation material a strength
thereof is lower than a fracture strength of said member or
members.
79. An adhesive to be used for a reinforcing member to be installed
on a member or members of a structure to reinforce said member or
members, wherein in said adhesive a strength thereof is lower than
a fracture strength of said member or members.
80. An adhesive to be used for a reinforcing member to be installed
on a member or members of a structure to reinforce said member or
members, wherein said adhesive boundary-surface peeling energy is
to be a product specification value, thereby a breaking of said
adhesive layer does not cause breaking said member or members.
81. An adhesive to be used for a reinforcing member to be installed
on a member or members of a structure to reinforce said member or
members, said adhesive not applying a solvent, to thereby remove a
harmful effect to a human body.
82. An adhesive to be used for a reinforcing member to be installed
on a member or members of a structure to reinforce said member or
members, said adhesive being a one-component, to thereby simplify a
fixation process.
83. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, said reinforcing structure having a high
bendability to fit an edge or edges of said member or members, and
to follow a deformation of said member or members without breaking
said member or members so as to maintain a reinforcement
effect.
84. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member has a high bendability and an elasticity, with a
Young's modulus not greater than that of said member or members to
follow a deformation of said member or members so as to maintain a
reinforcement effect.
85. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member has a high bendability and an elasticity, with a
Young's modulus in the range of 500 to 50,000 Mpa to follows a
deformation of said member or members so as to maintain a
reinforcement effect.
86. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member allows a flexural rigidity and shear rigidity to
be low, to thereby prevent said reinforcing member breaking said
member or members till after said member or members deformed.
87. The reinforcing structure as defined in claim 84, wherein a
reinforcing member, which has a Young's modulus to be a product
specification value, is installed.
88. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure a design
size thereof is determined by the product of a Young's modulus and
thickness of said reinforcing member.
89. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member has an elasticity and a high ductility, with a
tensile fracture strain thereof not greater than that of said
member or members, to thereby maintain practically a load of said
member or members till after said member or members broken.
90. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member has a high ductility and elasticity, with a
Young's modulus in the range of 500 to 50,000 Mpa, to thereby
prevent said reinforcing member breaking said member or members
till after said member or members deformed.
91. The reinforcing structure as defined in claim 89, wherein a
tensile fracture strain of said reinforcing member is 10% or
more.
92. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member has a tensile fracture strain to be a product
specification value.
93. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member, which has a high bendability, is installed
without chamfering of said member or members or grouting between
spaces of said member or members, and follows a deformation of said
member or members so as to maintain a reinforcement effect.
94. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member is installed on said member or members through a
filler material in a space between the reinforcing member and said
member or members, and a shear strength of said filler material is
lower than said member or members and said reinforcing member, to
thereby maintain a reinforcement effect by confining an apparent
volume expansion till after said member or members deformed.
95. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure said
reinforcing member, which comprises a plurality of materials having
a variant Young's modulus and fracture strain, is installed, to
thereby maintain a reinforcement effect from an early stage of said
member or members deformed till after said member or members
broken.
96. A reinforcing structure comprising a reinforcing member to be
fixed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure a fixation
strength is lower than a fracture strength of said member or
members, thereby a breaking of a fixation part does not occur.
97. The reinforcing structure as defined in claim 96, wherein said
fixation essentially consists of an adhesive.
98. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure by an adhesive to
reinforce said member or members, wherein in said reinforcing
structure said adhesive is a non-solvent adhesive, thereby no
harmful effect is given to a human health.
99. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure by an adhesive to
reinforce said member or members, wherein in said reinforcing
structure said adhesive is a one-component, thereby a reinforcing
structure forming process is simplified.
100. A reinforcing structure comprising a reinforcing member to be
installed on a member or members of a structure by an adhesive to
reinforce said member or members, wherein in said reinforcing
structure said adhesive has a boundary-surface peeling energy to be
a product specification value, thereby a breaking of said adhesive
layer does not cause breaking said member or members.
101. A reinforcing structure comprising a reinforcing member to be
fixed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing structure a size of
said reinforcing member is determined so as to obtain a required
reinforcement effect by fixation strength or boundary-surface
peeling energy.
102. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member has a high bendability to fit an edge or edges
of said member or members, and to follow a deformation of said
member or members without breaking said member or members so as to
maintain a reinforcement effect.
103. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which has a high bendability and an elasticity,
with a Young's modulus equal to or less than that of said member or
members, is installed, and follows a deformation of said member or
members without breaking said member or members so as to maintain a
reinforcement effect.
104. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method a design size
thereof is determined by the product of a Young's modulus and
thickness of said reinforcing member.
105. The reinforcing method as defined in claim 103, wherein said
reinforcing member, which has a Young's modulus to be a product
specification value, is installed.
106. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which has a tensile fracture strain to be a
product specification value, is installed.
107. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which has an elasticity and a high ductility,
with tensile fracture strain thereof equal to or more than that of
said member or members, is installed, to thereby maintain
practically a load of said member or members till after said member
or members broken.
108. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which has a high ductility and an elasticity,
with a Young's modulus in the range of 500 to 50,000 Mpa, is
installed, and follows a deformation of said member or members so
as to maintain a reinforcement effect.
109. The reinforcing method as defined in claim 104, wherein a
tensile fracture strain of said reinforcing member is 10% or
more.
110. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which has a high bendability, is installed
without chamfering of said member or members or grouting between
spaces of said member or members, to thereby maintain a
reinforcement effect till after said member or members
deformed.
111. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member is installed between spaces of said member or
members through a filler material whose shear strength is lower
than said member or members and said reinforcing member, to thereby
maintain a reinforcement effect by confining an apparent volume
expansion till after said member or members deformed.
112. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said
reinforcing member, which comprises a plurality of materials having
a variant Young's modulus and fracture strain, is installed, to
thereby maintain a reinforcement effect from an early stage of said
member or members deformed till after said member or members
broken.
113. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method a fixation
strength allows to be less than a fracture strength of said
structural member, thereby breaking a fixation part does not
occur.
114. The reinforcing method as defined in claim 114, wherein said
fixation essentially consists of an adhesive.
115. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said adhesive
is a non-solvent adhesive, thereby no harmful effect is given to a
human health.
116. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method said adhesive
is a one-component, thereby a reinforcing structure forming process
is simplified.
117. A reinforcing method comprising a reinforcing member to be
installed on a member or members of a structure to reinforce said
member or members, wherein in said reinforcing method an adhesive,
which has a boundary-surface peeling energy to be a product
specification value, is applied.
118. The reinforcing structure as defined in claim 82, wherein said
member or members is at least one selected from the group
consisting of: concrete; steel frame; brick; block; gypsum board or
plaster board; wood; rock; earth or soil; sand; resin; and
metal.
119. The reinforcing method as defined in claim 83, wherein said
member or members is at least one selected from the group
consisting of: concrete; steel frame; brick; block; gypsum board or
plaster board; wood; rock; earth or soil; sand; resin; and metal.
Description
TECHNICAL FIELD
[0001] The present invention relates to a reinforcing member for a
structural body, a reinforced structure using the reinforcing
member, and a method for designing the reinforcing member.
BACKGROUND ART
[0002] Heretofore, there have been known various techniques
(reinforced structures, reinforcing members and reinforcing
methods) for reinforcing a member of a structural body (hereinafter
referred to as "structure member"). Among them, a conventional
technique characterized by installing a reinforcing member on the
surface of or inside a structure member subject to reinforcement
includes (1) a technique of embedding a reinforcing bar in concrete
as a substrate, or so-called reinforced concrete technique, (2) a
technique of driving a bolt or nail into a substrate, (3) a
technique of incorporating a high-strength steel rod inside
concrete as a substrate and introducing a tensile force to the
steel rod, (4) a technique of wrapping a steel plate around a
structure member, or so-called steel-plate wrapping technique, and
(5) a technique of using a so-called continuous-fiber reinforcing
member made of carbon or aramid fibers and resin, such as epoxy
resin, impregnated therein.
[0003] Another conventional technique characterized by installing a
reinforcing member between the respective outer surfaces of
adjacent structure members includes (6) a technique of forming a
space, such as hole or slit, in the structure members, and
penetratingly inserting a reinforcing member into the space, and
(7) a technique of forming a space in the structure members,
penetratingly inserting bundled fibers of a continuous-fiber
reinforcing member into the space, and then spreading out the
fibers.
[0004] Still another conventional technique characterized by
installing a reinforcing member on the surface of a flat structure
member, such as wall, includes (8) a technique of constraining a
reinforcing member by a metal plate formed with a hole, and a bar,
such as a metal bar, penetrating the structure member, and (9) a
technique of bundling the fibers of a continuous-fiber reinforcing
member at the edge of the structure member, and anchoring the
bundled fibers to the edge of the structure member or another
member adjacent to the structure member.
[0005] Yet another conventional technique characterized by forming
a reinforcing member in a cylindrical shape and filling the inner
space of the cylindrical reinforcing member with filler includes
(10) a technique of forming an iron reinforcing member in a
cylindrical shape, and filling the inner space of the cylindrical
reinforcing member with concrete to use the obtained reinforcing
member as a column.
[0006] Yet still another conventional technique characterized by
installing a plurality of reinforcing members on the outer surface
of a structure member in a superimposed manner includes (11) a
technique of providing a plurality of continuous-fiber reinforcing
members on the outer surface of a structure member in its vertical
and horizontal directions in a superimposed manner.
[0007] Another further conventional technique characterized by
providing a strip-shaped reinforcing member on the outer surface of
a structure member includes (12) a technique of providing a
strip-shaped (tape-shaped) steel plate or continuous-fiber
reinforcing member around a structure member, (13) a technique of
filling epoxy resin along a crack of a substrate in a strip shape,
and (14) a technique of fixing a strip-shaped steel plate on the
surface of a structure member by use of epoxy resin or an anchor
bolt.
[0008] Still a further conventional technique characterized by
installing a reinforcing member on the outer surface of a junction
of structure members includes (15) a technique of providing a steel
jacket or attaching a continuous-fiber reinforcing member on the
outer surface of a junction of structure members.
[0009] An additional conventional technique characterized by using
a resin-impregnated reinforcing member includes (16) a technique of
using a so-called continuous-fiber reinforcing member made of
carbon or aramid fibers and epoxy resin impregnated therein.
[0010] The above techniques (4) to (14) are intended to transmit a
shear stress directly to a reinforcing member without causing any
displacement or peeling between a substrate and the reinforcing
member. For example, the shear reinforcement effect of a reinforced
concrete member is said to have the same mechanism as that of a
shear-reinforcing bar, and the reinforced concrete member is
designed by assigning a reinforcement amount and coefficients
expressing the property and reinforcement effect of a reinforcing
member to a design formula of the shear-reinforcing bar. Most of
the techniques (3) and (15) also include the step of injecting a
grouting or resin material between a reinforcing member and a
substrate to transmit a shear stress directly to the reinforcing
member. The term "substrate" herein means a material constituting a
structure member, and a physical object to which a reinforcing
member is to be fixed.
[0011] Therefore, an intended reinforcement effect can be obtained
only if a substrate is maintained in its proper state, and no
displacement or peeling is caused between the substrate and the
reinforcing member. This prerequisite must be guaranteed by the
design technique and construction management.
[0012] The reinforcing member, such as the reinforcing bar, the
steel rod and the steel plate, used in the techniques (1) to (4),
(6), (8), (10), (12), (14) and (15), has the flexural rigidity and
shear rigidity of its own. Thus, if a substrate is locally
subjected to a large strain, the reinforcing member cannot follow
the local strain, resulting in loss of the reinforcement effect due
to the occurrence of local fracture in the substrate or local
buckling or cracks in the reinforcing member.
[0013] In the techniques (12) and (16), the reinforcing member made
of resin-impregnated continuous fibers has the same problem as
described above due to the flexural and shear rigidities resulting
from the effect of resin impregnation in addition to the flexural
and shear rigidities of the continuous fibers themselves. Further,
while this reinforcing member is designed using a formula based on
the assumption that it has only tensile rigidity, an intended
reinforcement effect is actually likely to be lost due to
occurrence of bending or local buckling in consequence of the
flexural rigidity and shear rigidity of its own.
[0014] The material, such as carbon or aramid fibers, used in the
techniques (5), (7), (11) and (16), has a fracture strain of 2% to
several %, which is liable to cause damages by the corners of a
substrate or the unevenness of the surface of a substrate. Thus, an
appropriate construction management is essentially required.
Further, if the substrate has some cracks due to a certain external
force, the reinforcing member will be locally broken, which leads
to significant deterioration or disappearance of the reinforcement
effect.
[0015] In the techniques (1) to (15), if a structure member
contacting with another structure member or having a flat shape or
a concavo-convex or irregular surface is reinforced by forming a
through-hole therein and penetratingly inserting a reinforcing
member into the through-hole, such a construction work will involve
a problem of high cost and/or extended period, and a particular
technology or tool will be required to fix the edge of the
reinforcing member or insert the reinforcing member.
[0016] In the above technique, a plate, a rod or a bundle of
continuous fibers which serves as an anchor portion of the
reinforcing member (hereinafter referred to as "anchor member") has
a structure and rigidity different from those of the remaining
portion of the reinforcing member. Thus, the threshold value of the
reinforcement effect is undesirably defined by the threshold values
of stress transmission between the reinforcing and anchor members
and between the anchor member and the substrate.
[0017] Further, the substrate is requited to bear the stress
occurring at the fixed portion of the anchor member. Therefore, if
the strength of the substrate is lowered due to aged deterioration
or such an aged deterioration is calculated, the above technique
cannot be applied.
[0018] In the technique of introducing a tensile force to a steel
rod, if it is applied to a substrate exhibiting significant creep,
such as concrete, the tensile force of the steel rod will be
reduced due to the creep, and the reinforcement effect will be lost
across the ages. Further, if the anchor portion of the steel rod is
broken by a sudden external force due to earthquake or the like,
the steel rod suddenly freed from the tensile force will be likely
to jump out of the concrete and damage the surroundings.
[0019] Thus, the techniques (1) to (16) are required to install the
reinforcing member by spending an extended time in association with
professional engineers, which involves a high construction cost.
The application of these techniques is also limited to a specific
substrate which can be formed to have a smooth surface as in
reinforced concrete, and allows a reinforcing member to be brought
into close contact therewith so as to form a structure capable of
locally transmitting a shear force.
[0020] In the so-called continuous-fiber reinforcing member
composed of epoxy-resin-impregnated carbon or aramid fibers in the
technique (16), material constants, such as strength and Young's
modulus, important in reinforcement design are defined in the state
after the fibers are impregnated with the resin. This reinforcing
member is fixed to a structural body, for example, according to the
following process as disclosed in Japanese Patent Laid-Open
Publication No. 8-260715.
[0021] (i) Pre-cleaning the surface of a structural body by
removing/repairing stains and damages, such as cracks, thereon,
[0022] (ii) Applying a primer on the surface,
[0023] (iii) Uniformly applying a powerful adhesive, such as epoxy
resin, on the surface,
[0024] (iv) Wrapping the reinforcing member around the structural
body to cover over the surface while stretching the reinforcing
member and keeping it from loosing,
[0025] (v) Re-applying the adhesive on the surface of the
reinforcing member and impregnating the reinforcing member with the
adhesive, and
[0026] (vi) Curing the adhesive for given days, and applying on the
surface of the reinforcing member an appropriate coating material
for protecting the reinforcing member from ultraviolet light or the
like.
[0027] The reinforcing member is fixed through the many steps as
described above, and the adhesive in the step (v) can be applied
only after the adhesive applied in the step (iii) is completely
cured or hardened by chemical action (if the adhesive in the step
(v) is prematurely applied, gas bubbles generated during the
chemical action will be confined in the reinforcing member to cause
the deterioration in strength of the reinforcing member. Thus, the
above process has to be completed by taking a great number of
days.
[0028] The impregnating step has to be carried out in the working
site under a strict construction management. If an external force
acts to cause the peeling between the resin and the continuous
fibers, or the resin is defective in curing or deteriorated due to
environmental conditions, the design performance of the reinforcing
member will be significantly degraded.
[0029] Generally, if a structure member has a non-flat or irregular
surface, such as a wall-mounted column, or is joined to or located
very close to another member or non-structural material, such as a
column having a window frame attached thereto, it is difficult to
obtain a sufficient reinforcement effect. Further, the interactions
between a structure member and a reinforcing member and between the
reinforcing member and the surrounding are likely to cause
deterioration of the reinforcing member. Furthermore, there is the
need for obtaining a sufficient reinforcement effect in a wide
range from a small deformation to a large deformation.
DISCRIPTION OF THE INVENTION
[0030] According to a first aspect of the present invention, there
is provided a reinforcing member comprising a woven body formed by
a weaving process to have a high ductility and high bendability.
The reinforcing member is adapted to be installed on a surface of
or inside a structure member to reinforce the structure member. The
woven body has a Young's modulus equal to or less than that of the
structure member, and a tensile fracture strain of 10% or more.
[0031] In the reinforcing member set forth in the first aspect of
the present invention, the Young's modulus of the woven body may be
in the range of 1/2 to 1/20, preferably 1/5 to 1/10, of that of the
structure member. Specifically, the Young's modulus of the woven
body may be in the range of 500 to 50000 MPa, preferably 1000 to
10000 MPa.
[0032] The woven body may have a thickness in the range of 0.2 to
20 mm, preferably 0.5 to 15 mm, more preferably 1 to 10 mm.
[0033] The woven body may include yarns made of polyester.
[0034] The woven body may have a bending deformation angle of
90-degree or more, and a shear deformation angle of 2-degree or
more.
[0035] The reinforcing member set forth in the first aspect of the
present invention may be heat-set to allow a Young's modulus in a
limit state to be greater than a Young's modulus immediately before
fracture. The heat setting process comprises the steps of heating
the reinforcing member to apply a tensile force thereto, and then
cooling the reinforcing member while maintaining the tensile force,
so as to provide enhanced initial rigidity and Young's modulus to
the reinforcing member. In addition, a resin impregnation process
may be performed to impregnate the reinforcing member with
resin.
[0036] This reinforcing member may have an elongation strain in the
range of 0.1% to 10% in the limit state.
[0037] According to a second aspect of the present invention, there
is provided a reinforcing member comprising a tape-shaped or
sheet-shaped body made of a rubber-based or resin-based elastic
material having a high ductility and high bendability. The
reinforcing member is adapted to be installed on a surface of or
inside a structure member to reinforce the structure member. The
tape-shaped or sheet-shaped body has a Young's modulus equal to or
less than that of the structure member, and a tensile fracture
strain of 10% or more.
[0038] In the reinforcing member set forth in the second aspect of
the present invention, the Young's modulus of the tape-shaped or
sheet-shaped body may be in the range of 1/2 to 1/20, preferably
1/5 to 1/10, of that of the structure member. Specifically, the
Young's modulus of the tape-shaped or sheet-shaped body may be in
the range of 500 to 50000 MPa, preferably 1000 to 10000 MPa.
[0039] The tape-shaped or sheet-shaped body may have a thickness in
the range of 0.2 to 20 mm, preferably 0.5 to 15 mm, more preferably
1 to 10 mm.
[0040] The tape-shaped or sheet-shaped body may have a bending
deformation angle of 90-degree or more, and a shear deformation
angle of 2-degree or more.
[0041] As long as meeting the aforementioned requirement, the
reinforcing member set forth in the second aspect of the present
invention may be formed by spraying or applying a rubber-based or
resin-based material or fiber-reinforced mortar to the structure
member in the working site. While the material cost in this case is
higher than the polyester woven fabric, it is often the case that
such a reinforcing member is advantageous in terms of the ratio of
reinforcement effect to cost as compared to conventional
techniques. A Young's modulus in a limit state such as a design
ultimate state, a fracture strain and a fracture stress can be
calculated based on the stress-strain relationship of the
reinforcing member to determine a required reinforcement amount
(the thickness of the reinforcing member) and the performance of
the structure member according to an after-mentioned calculation
method.
[0042] According to third and fourth aspects of the present
invention, there are provided two types of reinforced structures
for a structural body. The reinforced structures comprise the
reinforcing members set forth in the first and second aspects of
the present invention, respectively. In these reinforced
structures, the reinforcing member is fixed on a surface of or
inside a substrate which constitutes a structure member of the
structural body and consists of at least one material, or on a
surface of a boundary portion of the structure member or inside the
structure member, to reinforce the structure member.
[0043] In the reinforced structures set forth in third and fourth
aspects of the present invention, the reinforcing member may be
fixed to the structure member in such a manner that an effective
constraint range of the reinforcing member covers the
pre-calculated width and length of a gap to be generated in the
structure member in future.
[0044] The substrate may be made of at least one material selected
from the group consisting of (1) concrete, (2) steel frame, (3)
brick, (4) block, (5) gypsum board or plaster board, (6) wood, (7)
rock, (8) earth or soil, (9) sand, (10) resin and (11) metal.
[0045] The fixation may be performed by means of an adhesive. The
layer of the adhesive applied to the reinforcing member or the
structure member may have a thickness in the range of 5 to 90%,
preferably 20 to 40%, of the thickness of the reinforcing
member.
[0046] The fixation may be performed by placing the reinforcing
member on the structure member through the layer of the adhesive
and then applying a pressing force or a beating force to the
reinforcing member while allowing a part of the adhesive to be
infiltrated into the reinforcing member. In case of the woven body,
the fixed portion of the reinforcing member may have a void ratio
of 1.1 or more. In case of the tape-shaped or sheet-shaped body,
the fixed portion of the reinforcing member may have a void ratio
of 1.4 or more.
[0047] The bonding strength of the fixation may be less than the
peeling/shear fracture strength between the structure member and
the reinforcing member. This prevents the reinforcement effect from
disappearing due to fracture in the structure member and the
reinforcing member before the occurrence of peeling in the fixed
portion. Specifically, the bonding strength may be in the range of
10 to 80% of peeling/shear fracture strength in the surface of the
structure member applied with the adhesive.
[0048] The adhesive may be a one-component, non-solvent
adhesive.
[0049] The fixation of the reinforcing member to the structure
member may be performed without chamfering the structure member and
adjusting the unevenness of the surface of the structure
member.
[0050] In the reinforced structures set forth in third and fourth
aspects of the present invention, even after the structure member
has a gap, the reinforcing member holds or constrains the structure
member in such a manner that it forms an envelope surface covering
a surface of the structure member adjacent to the gap to serve as a
medium for transmitting a stress acting on the structure member on
both sides of the gap (bridge for transmitting the stress). The
envelope surface serving as the transmission medium is formed by
elongation in the reinforcing member adjacent to the gap and/or
peeling in the fixed portion adjacent to the gap. In other words,
the envelope surface serving as the transmission medium is formed
by the elastic elongation of the reinforcing member in a free zone
where the fixation is released due to the generation of the
gap.
[0051] The term "substrate" means a material constitutes a
structure member subject to reinforcement, and a physical object to
which a reinforcing member is to be fixed. The shape and material
of the substrate are appropriately selected depending on a desired
performance or function of the structure member. The material of
the substrate is not limited to a specific form or type, and may be
any conventional structural material, any conventional
non-structural material or any filler material. For example, the
substrate may be concrete, steel frame, brick, block, gypsum or
plaster board, precast concrete, wood, rock, earth or soil, sand,
metal, or granular resin. The substrate may include plural kinds of
materials. For example, when a filler material such as resin is
filled in a space between a structure member and a reinforcing
member, the combination of the filler material and the material of
the structure member may be defined as the substrate. The term
"gap" herein means a chap or crack generated in a structure member.
When a structure member has a deformation inducing a gap therein,
the resulting displacement between the structure member and a
reinforcing member adjacent to the gap forms an envelope surface in
a portion of the reinforcing member around the gap of the structure
member without any fracture of the reinforcing member. The
enveloped surface serves as a bridge allowing a stress of the
structure member to be transmitted across the gap. That is, a shear
stress is transmitted through the boundary surface between the
reinforcing member and a portion of the structure member having no
gap or through a fixed portion. The envelope surface of the
reinforcing member is formed based on a plurality of factors
including as the elongation of the reinforcing member adjacent to
the gap, the release (peeling-or another factor) of the fixation
adjacent to the gap, and the fixation around the gap.
[0052] The fixation of a reinforcing member to a structure member
is performed by applying an adhesive a part or all of the boundary
surface between the structure member and the reinforcing member, or
by closingly looping a reinforcing members in an adhesive or
mechanical manner while enclosing and deforming a portion of the
structure member, so as to provide a tensile force in the
reinforcing members to generate a frictional or bearing force
between the reinforcing member and the structure members.
[0053] The adhesive to be applied to the boundary between a
structure member and a reinforcing member is required to maintain
an adhesion strength required for fixing the reinforcing member to
the structure member, for the period of use of the structure member
under environmental conditions of the structure member. In this
case, there is no need to set the required adhesion strength at a
value higher than the fracture strength of the structure member or
the reinforcing member. Thus, the adhesive may be one-component
adhesive. The adhesive may also be applied to the reinforcing
member in advance, and stored together with the reinforcing member.
In this case, an operation of fixing the reinforcing member can be
quickly completed.
[0054] The term "fixation zone" herein means a zone where the
reinforcing member is fixed. The term "free zone" means a zone
where the fixation of the reinforcing member is released (due to
peeling or another factor). In an after-mentioned design method,
the ratio of the size of the fixation zone to the size of the free
zone is expressed by a numerical value of "constraint ratio".
[0055] The terms "fixation strength" and "fixation range" herein
mean a strength and a range capable of causing the displacement in
a specific finite areas (free zone) of reinforcing and structure
members when the structure member has a local fracture inducing a
gap, so as to allow a stress of the structure member to be
transmitted through the reinforcing member across the gap without
any fracture of the reinforcing member.
[0056] The relationship between load and deformation of the
structure member after the generation of the gap is expressed as
the functions of the dimensions of the structure member, the
boundary condition of the structure member, the position and size
of the gap, the Young's modulus and thickness of the reinforcing
member, and the size of a free zone caused by the gap. Thus, a
required strength, required Young's modulus, required amount
(required installation range, required thickness etc.) and required
fixation strength of the reinforcing member can be calculated based
on a value in a limit state (tolerance or threshold value) of the
size (width etc.) of a gap to be generated in the structure member,
the size of a zone where the elongation of the reinforcing member
can be neglected (fixation zone), and the size of a zone where the
reinforcing member is to be elongated (free zone).
[0057] A Young's modulus for use in the calculation of the required
amount etc. of the reinforcing member is a value (limit state
value) corresponding to a strain to be generated in the reinforcing
member in a limit state where the size of the gap reaches the
threshold value. Therefore, in view of the elastic property of the
reinforcing member, the design of setting a Young's modulus in the
limit state to be greater than a Young's modulus corresponding to
another strain such as a strain immediately before fracture can
advantageously reduce the reinforcement amount.
[0058] The installation range of the reinforcing member is not
necessarily the entire surface of the structure member, but may be
a portion of the structure member. In this case, the reinforcing
member is installed to form an envelope surface in the
circumferential direction of the structure member or to form a
surface capable of being in contact with the portion of the surface
of the structure member smoothly from the outside.
[0059] The installation range of the reinforcing member is
selectively determined depending on a desired performance, shape or
configuration of a structure member, or a method of fixing a
reinforcing member. For example, if a plurality of structure
members are located adjacent to each other, the reinforcing member
may be installed such that an envelope surface is formed to cover
the junction between the adjacent structure members, or it is
penetratingly inserted into a hole or slit formed in the adjacent
structure members. Further, if the structure member is a flat
member such as a wall, a reinforcing member may be installed on
only one of the opposite surfaces thereof, or a reinforcing member
may be installed on the respective opposite surfaces thereof and
closingly looped through a through-hole formed in the structure
member.
[0060] The aforementioned reinforced structure may be formed by
providing a reinforcing member to a structure member of an existing
structural body, or may be formed by installing a reinforcing
member to a structure member of a structural body to be newly
constructed. When the reinforced structure is applied to a new
structural body, the size and weight of the structure member can be
reduced as compared to the conventional techniques to provide
reduced seismic load. This makes it possible to achieve drastically
reduced construction cost of the structural body, and significantly
enlarged utilizable space of a living room or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] FIG. 1 is a perspective view of a structure member 1 with a
reinforcing member 5.
[0062] FIG. 2 is a sectional view taken along line A-A of FIG.
1.
[0063] FIG. 3 is a perspective view of a structure member 1 with a
reinforcing member 5.
[0064] FIG. 4 is a perspective view of a structure member 1 with a
reinforcing member 5.
[0065] FIG. 5 is a graph showing the relationship between load and
deformation in a structure member 1.
[0066] FIG. 6 is a graph showing the relationship between
circumferential strain and deformation in a structure member 1.
[0067] FIG. 7 is a perspective view of a structure member divided
by a gap.
[0068] FIG. 8 is a sectional perspective view of a structure member
sliced perpendicular to the axis thereof in FIG. 7.
[0069] FIG. 9 is a graph showing a stress-stain relationship of a
reinforcing member.
[0070] FIG. 10 is a graph showing the relationship between load and
deformation in a non-reinforced model column.
[0071] FIG. 11 is a graph showing the relationship between load and
deformation in a SRF-reinforced model column.
[0072] FIG. 12 is a graph showing the relationship peak load in a
normal direction and deformation.
[0073] FIG. 13 is a graph showing the relationship elongation
strain in the circumferential length of a structure member and
deformation.
[0074] FIG. 14 is a perspective view of a wall-mounted column with
a reinforcing member.
[0075] FIG. 15 is a sectional view of the wall-mounted column in
FIG. 14.
[0076] FIG. 16 is a sectional view of the wall-mounted column in
FIG. 14.
[0077] FIG. 17 is a perspective view of an H-section structure
member 143 after reinforcement.
[0078] FIG. 18 is a perspective view of a hollow structure member
149 after reinforcement.
[0079] FIG. 19 is a partial sectional view of a reinforced member
181.
[0080] FIG. 20 is a graph showing the relationship between load and
deformation with respect to the member 181.
[0081] FIG. 21 is a plan view of a polyester belt 199.
[0082] FIG. 22 is a perspective view showing an example of a column
205 reinforced by use of a beltlike reinforcement 201.
[0083] FIG. 23 is a perspective view showing an example of a column
205 reinforced by use of a beltlike reinforcement 201.
[0084] FIG. 24 an elevation of the column 205 shown in FIG. 23.
[0085] FIG. 25 is a sectional view of a surface portion of the
column 205 shown in FIGS. 22 to 24.
[0086] FIG. 26 is a view showing an effective bond length between
the beltlike reinforcement 201 and a crack 215.
[0087] FIG. 27 is a schematic view of the column 205 subjected to
an axial force, bending, and a shear force.
[0088] FIG. 28 is a view showing a force which attempts to expand
the crack 215 formed in the column 205.
[0089] FIG. 29 is a view showing the deformation of the column
205.
[0090] FIG. 30 is a view showing horizontal force Q applied to the
column 205 and an envelope indicative of displacement hysteresis of
the column 205.
[0091] FIG. 31 is a view showing the relationship among the
horizontal displacement of the column 205, the vertical
displacement of the column 205, and a horizontal force applied to
the column 205.
[0092] FIG. 32 is a view showing restoring-force characteristics of
the column 205.
[0093] FIG. 33 is a view showing the relationship between
cumulative horizontal displacement .SIGMA..delta..sub.h and
hysteretic absorbed energy W in the column 205.
[0094] FIG. 34 is a detailed view of FIG. 33.
[0095] FIG. 35 is a view showing the relationship between
cumulative horizontal displacement .SIGMA..delta..sub.h and
vertical displacement .delta..sub.v.
[0096] FIG. 36 is a perspective view showing a state in which
connecting reinforcements 269a and 269b are disposed on the joint
between a column 261 and a beam 263.
[0097] FIG. 37 is a perspective view showing a state in which a
beltlike reinforcements 271a and 271b are disposed on the joint
between the column 261 and the beam 263.
[0098] FIG. 38 is a sectional view of the joint between the column
261 and the beam 263 on which the connecting reinforcements 269b,
etc. are disposed.
[0099] FIG. 39 is a design flowchart for determining the amount of
reinforcement.
[0100] FIG. 40 is a design flowchart for determining the amount of
reinforcement.
[0101] FIG. 41 is a diagram showing the relationship between
cumulative deformation and hysteretic absorbed energy with respect
to a reinforced member.
[0102] FIG. 42 is a diagram showing the relationship between
tensile stress and strain with respect to a reinforcement material
impregnated with resin and a reinforcement material unimpregnated
with resin.
[0103] FIG. 43 is a diagram showing properties (test
specifications) of the tested columns, loading conditions, test
results, and SRF reinforcement effects etc.
[0104] FIG. 44 is an explanatory diagram of the relationship
between the width of a gap and the elongation of a reinforcing
member.
[0105] FIG. 43 is a diagram showing the relationship between the
tensile force of a reinforcing member and the relative displacement
of a structure member in a SRF-reinforced structure.
BEST MODE FOR CARRYING OUT THE INVENTION
[0106] With reference to the drawings, various embodiment of the
present invention will now be described in detail.
[0107] FIG. 1 is a perspective view of a structure member (or a
member of a structural body) with a reinforcement member according
to an embodiment of the present invention. FIG. 2 is a sectional
view taken along the line A-A in FIG. 1. As shown in FIGS. I to 3,
a structure member 1 comprises a substrate 3 with a reinforcing
member 5. The reinforcing member 5 is installed, for example, in
such a manner that it envelops a portion of the surface of the
substrate 3 (see FIG. 1), or it encloses a given portion (periphery
etc.) of the substrate (FIG. 3). The substrate 3 is principally a
material constituting the structure member 1 subject to
reinforcement, and a physical object to which the reinforcing
member 5 is to be fixed. The shape and material of the substrate 3
are appropriately selected depending on a desired performance or
function of the structure member 1. The substrate 3 is a structural
material such as reinforced concrete, a non-structural material
such as block or brick, or a filler material such as sand or
granular resin. The reinforcing member 5 installed on the surface
the substrate 3 acts to bear a stress of the substrate 3 while
bridging between both sides of a fractured surface such as chap or
crack (or gap) generated in the substrate.
[0108] In addition to the above function, a reinforcing member 5
according to a first mode of embodiment is composed of a woven body
having all of extensibility (high ductility and high bendability),
strength and elasticity, and adapted to be installed on the surface
of or inside a substrate of a structural body to reinforce the
substrate. The woven body characteristically has a Young's modulus
equal to or less than that of the structure member (substrate), and
a tensile fracture strain of 10% or more.
[0109] When the structure member includes plural kinds of primary
substrates (materials), the term "Young's modulus of the structure
member (substrate)" herein means the lowest one in the respective
Young's moduluses of the materials.
[0110] As above, the reinforcing member has high ductility and high
bendability, or extensibility. The term "high ductility" means to
have a large fracture strain. The term "high bendability" means to
readily cause a large bending deformation and shear deformation
(high flexibility) without fracture.
[0111] Even if a substrate is deformed to have a gap or irregular
surface, the reinforcing member having high ductility can constrain
the substrate without fracture to maintain a desired reinforcement
effect.
[0112] The reinforcing member having high bendability can be
readily bent at an acute angle. Thus, the reinforcement can be
installed along an irregular circumferential surface of a structure
member, and can be deformed under load to have a fixed portion
formed in conformity to the curvature or corner angle of a
substrate.
[0113] The reinforcing member is required to have elasticity for
generating a tensile force in response to change in the
circumferential length of a substrate to bring out a geometrical
constraint effect and coping with a repeated alternate load or the
like. Preferably, the rigidity of the reinforcing member is greater
at the initial stage of the generation of strain than immediately
before fracture.
[0114] In the present invention, the Young's modulus of the woven
body constituting the reinforcing member 5 is set to be equal to or
less that that of the structure member. This is intended to reduce
a stress acting on the boundary surface the reinforcing member and
the substrate 3 when the reinforcing member starts deforming in
response to the occurrence of deformation or crack in the structure
member 1 due to a load acting on the substrate 3, so as to increase
a limit deformation causing peeling in the boundary surface.
Further, the tensile fracture strain of the woven body is set at
10% or more. Because in the design of structural bodies for an
accidental load due to earthquake or the like, a design limit is
generally about 2 to 4% of deformation in a structure member.
Additionally considering a local-strain-concentration coefficient
of 5, the reinforcing member would be not fractured in the design
limit if the fracture strain is 10% or more. According to the
results of loading tests of a structure member, in case where a
reinforcing member including aramid fibers having several % of
fracture strain was bonded on a surface of a structure member, the
fracture of the reinforcing member was observed. On the other hand,
in case where the structure member was reinforced by a SRF
reinforcing member having 10% or more of fracture strain, no
fracture was observed in the reinforcing member
[0115] By contrast, in the reinforcing member disclosed in the
aforementioned Japanese Patent Laid-Open Publication No. 8-260715,
the Young's modulus and fracture strain of aromatic polyamide
fibers used therein are directly applicable. Thus, the Young's
modulus is in the range of 80000 to 120000 MPa, and the tensile
fracture strain is in the range of 2.5 to 4.5%. Further, when the
aromatic polyamide fibers act as an actual reinforcing member, it
will be an aromatic-polyamide-fiber-rein- forced epoxy resin having
higher bending and shear rigidities than those of the elemental
fibers. As a result, the reinforcing member is likely to peel off
over a wide range at the same time due to inability of following
the deformation of a substrate. In this connection, the Young's
modulus of concrete is about 20000 MPa, and the Young's modulus of
hard wood such as oak is about 10000 MPa.
[0116] The Young's modulus of the woven body is preferably in the
range of 1/2 to 1/20, more preferably 1/5 to 1/10, of that of the
substrate. If the Young's modulus is less than the lower limit of
the range (or the value of Young's modulus is excessively small),
the reinforcing member has to be designed to have an increased
thickness to obtain a desired reinforcement amount. This is
economically inefficient. Further, as described later, a
peeling-limit elongation (.delta.1: FIGS. 44 and 45) is increased,
resulting in delayed response of the reinforcement effect and
increased damage of the structure member.
[0117] Specifically, the Young's modulus of the reinforcing member
is preferably in the range of about 500 to 5000 MPa, more
preferably about 1000 to 1000 MPa.
[0118] Preferably, the tensile fracture strength of the woven body
is in the range of 3 to 5 times of that of the structure member.
Any local fracture of the structure member can be avoided by
setting a stress concentration coefficient in the range of 3 to
5.
[0119] The thickness of the woven body is preferably in the range
of 0.2 to 20 mm, more preferably 0.5 to 15 mm, particularly 1 to 10
mm. This range is desired to obtain an intended performance and
facilitate handling.
[0120] Preferably, the material of strings constituting the woven
body is polyester (fiber).
[0121] Preferably, the woven body has a bending deformation angle
of 90-degree or more, and a shear deformation angle of 2-degree or
more.
[0122] Preferably, the woven body is heat-set to allow a Young's
modulus in a limit state to be greater than a Young's modulus
immediately before fracture.
[0123] Preferably, the reinforcing member has an elongation strain
in the range of 0.1% to 10% in the limit state.
[0124] A reinforcing member according to a second mode of
embodiment is a tape-shape or sheet-shaped body made of a
rubber-based or resin-based elastic material, and adapted to be
installed on a surface of or inside a substrate of a structural
body to reinforce the substrate. Further, the tape-shaped or
sheet-shaped body has a Young's modulus equal to or less than that
of the structure member, and a tensile fracture strain of 10% or
more.
[0125] The Young's modulus of the tape-shaped or sheet-shaped body
is preferably in the range of 1/2 to 1/20, more preferably 1/5 to
1/10, of that of the substrate. Specifically, the Young's modulus
of the reinforcing member composed of the tape-shaped or
sheet-shaped body is also preferably in the range of about 500 to
5000 MPa, more preferably about 1000 to 1000 MPa.
[0126] The thickness of the tape-shaped or sheet-shaped body is
preferably in the range of 0.2 to 20 mm, more preferably 0.5 to 15
mm, particularly 1 to 10 mm.
[0127] Preferably, the tape-shaped or sheet-shaped body has a
bending deformation angle of 90-degree or more, and a shear
deformation angle of 2-degree or more.
[0128] The above factors of the reinforcing member according to the
second mode of embodiment have been selectively determined in the
same way as that in the reinforcing member according to the first
mode of embodiment.
[0129] Two types of reinforced structures for a structural body
according to third and fourth modes embodiment of the present
invention comprise the reinforcing members according to the first
and second modes of embodiment, respectively. Further, the
reinforcing member is fixed on a surface of or inside a substrate
constituting a structure member and including at least one material
to reinforce the substrate.
[0130] In the reinforced structures, the reinforcing member is
preferably fixed to the substrate in such a manner that an
effective constraint range of the reinforcing member covers the
pre-calculated width and length of a gap to be generated in the
substrate in future.
[0131] In other words, the reinforcing member 5 is fixed to the
substrate 3 in the structure member 1. More specifically, the
reinforcing member 5 and the substrate 3 are constrained to one
another. The mechanism of this constraint is roughly classified
into two types. A first mechanism is a bonding constraint, and a
second mechanism is a geometrical constraint.
[0132] The first mechanism or bonding constraint is achieved by
bonding the reinforcing member 5 to the substrate 3. In this case,
even after a gap is generate to create a zone where the bond is
separate (herein after referred to as "free zone"), as long as a
bonded portion exists around the free zone, the bonding constraint
can be maintained.
[0133] The thickness of the layer of an adhesive applied to the
reinforcing member or the substrate is preferably in the range of 5
to 90%, more preferably 20 to 40%, of the thickness of the
reinforcing member.
[0134] The fixation is performed by placing the reinforcing member
on the substrate through the layer of the adhesive and then
applying a pressing force or a beating force to the reinforcing
member while allowing a part of the adhesive to be infiltrated into
the reinforcing member. In case of the woven body, the fixed
portion of the reinforcing member preferably has a void ratio of
1.1 or more. In case of the tape-shaped or sheet-shaped body, the
fixed portion of the reinforcing member preferably has a void ratio
of 1.4 or more. In this way, gas generated during the curing
reaction of the adhesive can be adequately released from the
adhesive layer or the reinforcing member. Thus, an initial bonding
ability can be achieved without generation of gas bubbles in the
adhesive layer, defective bonding, and swollenness and float of the
adhesive layer. The upper limit of the void ratio is not limited to
a specific value, but preferably in the range of about 2 to 3.
[0135] Preferably, the bonding strength is less than the strength
of the substrate. If the bonding strength is equal to or greater
than the strength of the substrate, the fracture of the structure
member causes the generation of a tensile force in the reinforcing
member and the release of the bonding to annul the reinforcement
effect in a wide range at the same time. The bonding strength is
preferably in the range of 10 to 80% of peeling/shear fracture
strength in the surface of the substrate applied with the adhesive.
If the bonding strength is higher than the upper limit of the
range, the structure member will be damaged in an operation of
detaching the reinforcement. If the bonding strength is lower than
the lower limit of the range, a desired reinforcement effect cannot
be obtained. Specifically, the bonding strength is preferably in
the range of about 1 to 2 N/mm.sup.2. In this connection, the
peeling/shear fracture strength of concrete is about in the range
of 3 to 5 N/mm.sup.2.
[0136] By contrast, in the reinforcing member disclosed in the
aforementioned Japanese Patent Laid-Open Publication No. 8-260715,
the epoxy resin to be impregnated also serves as an adhesive. Thus,
if a structural body made of concrete is reinforced by this
reinforcing member, the bonding strength will become higher than
the strength of the substrate to cause the aforementioned
problems.
[0137] While any suitable adhesive satisfying the above condition
may be used, the adhesive is preferably a one-component,
non-solvent adhesive. This one-component, non-solvent adhesive may
include an epoxy-urethane-based, non-solvent, moisture-setting type
adhesive. This type of adhesive advantageously has no odor, no open
time and long lifetime.
[0138] The fixation of the reinforcing member to the structure
member or the substrate can be performed without chamfering the
structure member or the substrate and adjusting the unevenness of
the surface of the structure member or the substrate. By contrast,
in the reinforcing member disclosed in the aforementioned Japanese
Patent Laid-Open Publication No. 8-260715, it is practically
required to chamfer the substrate at R=10 mm or more due to aramid
fibers as a primary component of the reinforcing member. If carbon
fibers are used, R=20 mm or more of chamfering will be
required.
[0139] In the reinforced structures according to the third and
fourth modes of embodiment, the fixation can be achieved without
the large bonding strength as described above. Thus, there is no
need for any primer treatment and any anchoring operation after the
fixation. For example, only by winding the reinforcing member
around the structure member, even after peeling, the reinforcement
effect can be maintained by the geometrical constraint.
[0140] The adhesive 11 may be applied to the reinforcing member 5
at a working site of the bonding operation. Alternatively, the
adhesive 11 may be applied to the reinforcing member 5 in advance,
and stored until the bonding operation. In these reinforced
structures, in an operation of detaching or peeling the adhesive,
the substrate 3 or the reinforcing member is never damaged while
leaving the adhesive layer thereon.
[0141] When it is required to achieve the bonding constraint, as
shown in FIG. 1, the reinforcing member 5 is installed in a range
(reinforcing-member installation range 9) extending outward from a
range (effective bonding constraint range 7) for reinforcing the
structure member 1. The effective bonding constraint range 7 is
selectively determined depending on a required performance or
function of the structure member 1. The effective bonding
constraint range 7 may be a portion of the surface of the structure
member 1. In this case, the reinforcing member 5 is installed to
form an envelope surface in the circumferential direction of the
structure member 1 or to form a surface capable of being in contact
with the portion of the surface of the structure member smoothly
from the outside.
[0142] The second mechanism or geometrical constraint is achieved,
for example, by bonding both ends of a reinforcing member and
installing the reinforcing member in such a manner that it encloses
a given portion (periphery etc.) of a substrate 3, as shown in FIG.
3. In this case, the substrate 3 and the reinforcing member 5 is
geometrically connected together, and constrained to one
another.
[0143] More specifically, in conjunction with the deformation of
the substrate, the length of the closed or looped reinforcing
member is changed to generate a tensile force in the reinforcing
member. If the reinforcing member is installed in conformity to the
curvature or corner angle of the substrate, the tensile force will
cause the frictional force or bearing force between the reinforcing
member and the substrate so that the substrate and the reinforcing
member exert a constraint force against deformation to one another.
In case where a reinforcing member is bonded in conformity with the
corner angle of a substrate, it can be expected to have a
geometrical constraint-like effect such that the bearing force of
the bonded surface at the corner is increased by the tensile force
of the reinforcing member to provide enhanced bonding strength.
[0144] While the geometrical constraint is changed depending on the
shape of the substrate 3, the relative positional relationship
between the reinforcing member 5 and the substrate 3, it can be
maintained until the reinforcing member 5 is fractured even if the
substrate 3 is fractured. On the other hand, the bonding constraint
disappears when the substrate 3 is fractured, and the bonding
strength becomes lower than a given value as described later.
[0145] The quantification of the effect of the reinforcing member
(reinforcement effect model) will be described below. FIG. 4 is a
perspective view showing a portion of a structure member 1 having
the reinforcing member 5 installed thereon, wherein the reinforcing
member 5 elastically constrains a substrate 3 having a gap 13. The
gap is a crack or chap generated in the substrate 3. A gap width 15
(d) means the width of the gap 13.
[0146] Upon deformation of the structure member 1, a stress is
concentrated on the reinforcing member and the surface of the
structure member 1 adjacent to the gap 13 to cause the peeling of
the reinforcing member 5 from the surface of the structure member
1. In the following description, this peeled area is referred to as
"free zone 19", and the length of the free zone 19 associated with
the region having a width 23 (.DELTA.w) of the reinforcing member 5
is referred to as "free length (a)". In the area where the bonding
or geometrical constraint is achieved, the reinforcing member 5 and
the structure member are constrained to one another.
[0147] In the following description, this constrained area is
referred to as "constraint zone 21", and the length of the
constraint zone 21 associated with the region having the width 23
(.DELTA.w) of the reinforcing member 5 is referred to as
"constraint length (a)". When a free zone is generated, a fixation
length (s) is reduced from a constraint length (b) by a factor of a
free length (a). In this case, a certain shear force, such as a
bonding or frictional force, acts between the reinforcing member 5
and the substrate 3 in a zone (fixation zone) of the fixation
length (s=b-a). While it can be technically said that the
constrained area is enlarged as the free length is increased, this
hypothesis will be ignored in the following calculation in view of
a risk-free approximate calculation.
[0148] Given that in a portion of the reinforcing member 5 of the
width 23 (.DELTA.w).times.the constrained zone 21 (constrained
length (b)), an average value of shear stresses 18 acting between
the surface of the substrate 3 and the non-peeled reinforcing
member 5 is Tf, and a tensile force, Young's modulus and thickness
in the free zone 19 of the reinforcing member 5 being q, E.sub.f
and t, respectively. The tensile force 17 and the resultant of the
shear stresses 18 are balanced in the fixation zone, and thus the
following relational expression is formulated. In the following
relational expression, the reinforcing member is presupposed as an
elastic body, and the elongation in the region of the fixation
length is ignored because it is small as compared to the elongation
in the free zone. 1 q = dE f t w a = ( b - a ) f w [ 1 ]
[0149] The following relational expression can be obtained by
eliminating "a" from the expression [1], dividing by t.DELTA.w, and
giving that a tensile stress of the reinforcing member 5 is
.sigma..sub.f. 2 f 2 - b t f f + d t E f f = 0 [ 2 ]
[0150] From the condition of the real root of .sigma..sub.f, it can
be proved that a gap width d is between 0 (zero) and 3 d max = b 2
f 4 E f t . [ 3 ]
[0151] For a certain gap width d, two of .sigma..sub.f will be
derived as a solution. Given that larger one of them is achieved, a
maximum value .sigma..sub.fmax and a minimum value .sigma..sub.fmin
of .sigma..sub.f are expressed as follows: 4 f max = b t f , f min
= 0.5 f max [ 4 ]
[0152] .sigma..sub.fmax is a stress in the condition of the gap
width d=0 or at the time when the gap 13 is just generated on the
surface of the structure member 1. .sigma..sub.fmin is a stress at
the time when the gap 13 is enlarged, and the gap width d reaches a
value d.sub.max in the expression [3]. According to the expressions
[1] to [3], when the tensile stress of the reinforcing member 5 is
.sigma..sub.fmin, the free length (a) is calculated as 1/2 of the
constraint length (b). If the gap width d is increased at a value
larger than dmax, the expression [1] will be invalid in view of
dynamical theories, the free length (a) will be sharply increased
until a certain constraint such as geometrical constraint is given
again.
[0153] The change in the length (hereinafter referred to as
"circumferential length") L of the envelope (the circumference of
the envelope surface) can be presupposed as the change in the total
value d of the gap width across the circumference. Thus, the
following formula is satisfied between a circumferential strain
.phi. and the total value of the gap width measured along the
circumference. In the following formula, L.sub.0 is the
circumferential length before the generation of the gap.
d=.phi.L.sub.0 [5]
[0154] Further, given that the reinforcing member 5 is elongated
only in the free zone (free length a) where the fixation between
the reinforcing member 5 and the structure member 1 is separated,
the following relational expression of the circumferential strain
.phi. and the strain E.sub.f of the reinforcing member by focusing
on the elongation of the reinforcing member 5 installed to form the
envelope surface: 5 a L 0 = f [ 6 ]
[0155] wherein a/L.sub.0 is an index indicating the level of the
constraint, and thus hereinafter referred to as "constraint
rate".
[0156] The tensile force 17 (.sigma..sub.f) of the reinforcing
member 5 can be calculated as follows in accordance with the strain
(.epsilon..sub.f) and Young's modulus (E.sub.f) of the reinforcing
member 5. In the following formula, a secant Young's modulus will
be used if the Young's modulus of the reinforcing member is changed
dependent on the strain thereof.
.sigma..sub.f=.epsilon..sub.fE.sub.f [7]
[0157] Given that after the structure member 1 is fractured by the
action of repeated load, it can be approximated as a granular body,
the following relational expression is satisfied: 6 f = B 2 t 3 [ 8
]
[0158] wherein B is the distance (sectional width) between the
reinforcing members, and .sigma..sub.3 is a constraint pressure of
the granular body.
[0159] The following relational expression can be obtained by
applying the relationship between the primary stress .sigma..sub.f
and constraint pressure .sigma..sub.3 of the granular body to the
expression [8]: 7 f = B ( 1 - sin ) 2 t ( 1 + sin ) 1 [ 9 ]
[0160] In the state of axial compression, the value of the primary
stress s.sub.1 can be approximated as a value derived from dividing
a compressive force by a pressure-receiving sectional-area. On the
other hand, under the condition of receiving a shear force, it is
required to calculate with the inclusion of the influence of the
shear force.
[0161] The relationship of the tensile force of the reinforcing
member, the deformation causing a gap of the structure member and
the fixation force is obtained from the expressions [3] to [7] and
[9]. Further, since the deformation causing a gap would represent
the level of the damage of the substrate, the relationship between
the damage of the substrate and the tensile force (or strain) of
the reinforcing member can also be obtained.
[0162] The above model is unconfined by the type of the gap 13.
Specifically, the model is applicable to any gap 13 caused by any
factor including a dynamical factor, such as bending or shear, and
a material factor, such as temperature, dryness, expansion or
deterioration. According to the model, particularly when the
reinforcing member 5 is installed in a direction crossing to a gap
13 caused by shear (shear chap, shear fracture surface, etc.), it
can elastically constrain the surrounding of the gap 13 to control
a shear deformation at a finite value and maintain the toughness of
the structure member 1.
[0163] Further, the above model is unconfined by the type of the
substrate 3. The substrate 3 may be any construction material, such
as reinforced concrete, steel framed reinforced concrete, steel
frame, brick, block, gypsum or plaster board, precast concrete
product, wood, rock, sand or resin. The substrate 3 may be an
existing structural or non-structural martial or a newly installed
material.
[0164] The installation of the reinforcing member 5 may be a
portion of the structure member as long as it is wider than an area
(effective bonding constraint range 7) corresponding to the
constraint zone 21 (constraint length (b)) for the crack or gap 13.
Referring to FIG. 1, the area of the effective bonding constraint
range 7 in the reinforcing-material installation range 9 is an
effective range.
[0165] According to the expressions [3] and [4], the reinforcement
effect is superficially increased in proportion to the bonding
strength. However, if the bonding strength is set at a value close
to the full strength of the substrate 3 or the reinforcing member
5, the substrate 3 or the reinforcing member 5 will be locally
fractured before generation of a free length (a) to annul the
reinforcement effect. Thus, the bonding strength is required to be
set at a level causing no fracture in the substrate 3 and the
reinforcing member 5 in the above process.
[0166] The aforementioned model can be achieved if the reinforcing
member 5 is not fractured by a stress concentration arising around
a crack or gap or at a corner of the structure member 1 in
connection with the generation and enlargement of the gap 1 in the
structure member 1. Thus, it is also required to provide
extensibility (large fracture strain) to the reinforcing member 5.
While carbon fibers or aramid fibers have a large elastic
coefficient and fracture strength, any material having a small
fracture strain is not suitable as the reinforcing member in the
first mode of embodiment and another after-mentioned mode of
embodiment.
[0167] The model can also be achieved if the reinforcing member
brings out a sufficient performance even after the adhesive layer
between the substrate and the reinforcing member is partly
fractured. Thus, a continuous-fiber reinforcing member whose
performance is defined under the condition of a structure in which
a a shear yield strength is increased as the deformation of the
structure member is increased. Therefore, a shear load-deformation
relationship has two extreme values, as described later in
conjunction with FIGS. 5, 12, etc.
[0168] FIG. 5 is a graph schematically showing the above
relationship between load and deformation. The horizontal axis
represents a deformation (deformation angle) in a structure member
1, and the horizontal axis represents a load acting on the
structure member 1. The shape of the curve is described by ten
parameters or Q.sub.max1, .alpha. Q.sub.max, Q.sub.mid, Q.sub.min,
Q.sub.max2 and R.sub.1 to R.sub.5. Q.sub.max1 is an initial maximum
vale of the load, .alpha. Q.sub.max being the load in a limit state
(design ultimate state etc.), Q.sub.min being a minimum value of
the load, Q.sub.mid being the load by which the bonding constraint
is released and shifted to the geometrical constraint, and
Q.sub.max2 being the load by which the reinforcing member 5 is
fractured, or the deformation of the structure member 1 reaches at
an extreme value and becomes unable to bear any load. R.sub.1 to
R.sub.5 are the deformations corresponding to Q.sub.max1, .alpha.
Q.sub.max, Q.sub.mid, Q.sub.min, Q.sub.max2, respectively. The
limiting point 27 (Q.sub.min, R.sub.4) is a point where the
structure member 1 is fractured by load, and starts exhibiting
behaviors of a granular body.
[0169] FIG. 6 is a graph showing the relationship between
circumferential strain and deformation in the structure member. The
horizontal axis represents a deformation (deformation angle) in the
structure member 1, and the horizontal axis represents a
circumferential strain in the structure member 1. The change in an
apparent volume, or a volume associated with an envelope surface,
of the structure member 1 is expressed by a circumferential strain
(strain in the circumferential length of the section of the
structure member 1 in a direction perpendicular to the axis thereof
and an axial strain (strain in the axis of the structure member 1).
The circumferential strain .phi. is changed as shown in the graph
29 in response to the carbon or another fibers bound by resin are
bonded on the surface of a substrate without float and wrinkle is
not suitable as the reinforcing member in the first mode of
embodiment and another after-mentioned mode of embodiment.
[0170] Further, the reinforcing member 5 is also required to have
elasticity to bring out a control effect to the phenomenon that the
gap 13 is opened and closed by a repeated alternate load.
[0171] The quantification of the performance of a structure member
1 (structure-member performance model) will be described below. The
dynamic performance and durability of the structure member can be
quantified in consideration of the performance of a substrate and a
desired reinforcement effect. The following description will be
made in conjunction with one example in which a substrate 3 of the
structure member 1 is a bar-shaped member made of reinforced
concrete, and the substrate 3 is reinforced by the reinforcing
member 5 and subjected to repeated shear.
[0172] As mentioned in connection with the reinforcement effect
model, even after a shear gap is generated in a structure member 1
due to a repeated shear force applied thereto, a shear force will
be transmitted through the reinforcing member 5 across the gap to
cause a bending deformation and maintain the toughness of the
structure member 1. The reaction force of the reinforcing member 5
is borne by the bonding constraint until the tensile force of the
reinforcing member 5 is increased up to .sigma..sub.fmin in the
expression [4], and subsequently borne by the geometrically
constraint.
[0173] Then, when the substrate 3 is increasingly fractured by the
work of repeated load action to have dynamic characteristics such
that they can be approximated as those of a granular body (dense
sands) having a surface covered by an elastic body, change of the
relationship between the load and the deformation in FIG. 5.
[0174] (R.sub.1, .phi..sub.1), (R.sub.2, .phi..sub.2), (R.sub.3,
.phi..sub.3), (R.sub.4, .phi..sub.4) and (R.sub.5, .phi..sub.5) in
FIG. 6 correspond (R.sub.1, Q.sub.max1), (R.sub.2, .alpha.
Q.sub.max), (R.sub.3, Q.sub.mid), (R.sub.4, Q.sub.min) and
(R.sub.5, Q.sub.max2), respectively.
[0175] The circumferential strain is gradually increased as the
bonding is separated to increase a free zone 19. In the range of
R.sub.3 to R.sub.4, the circumferential strain is kept
approximately constant by the geometrical constraint. When the
deformation goes beyond R.sub.4, the circumferential strain will be
increased again because the structure member 1 behaves as a
granular body. The axial strain is changed in the same manner as
that of the circumferential strain.
[0176] The result of an experimental verification will be described
below. While the structure member is described as a column in the
following description, it is not limited to such a column.
[0177] FIG. 7 shows the state when a region having the width 39 (H)
of a structure member 31 reinforced by a reinforcing member 37 is
divided into a first segmental member 33 a second segmental member
35 by a structural gap 41 (gap width 43 (d)), and the opposite ends
of the divided structure member receive the action of a shear force
45 (Q). The reinforcing member 37 is installed to form an envelope
surface in the circumferential direction of the structure member 31
or to form a surface capable of being in contact with the portion
of the surface of the structure member smoothly from the outside.
The shear force 45 is being transmitted between the first and
second segmental members 33, 35 through the reinforcing member 37
in each section.
[0178] FIG. 8 is a perspective view of the section (thickness 47
(.DELTA.H)) perpendicular to the axis of the structure member in
FIG. 7. Each of shear forces, reinforcing-member tensile stresses
51 (.sigma..sub.f), and tensile forces 53 (.sigma..sub.cs) of
concrete from the shear force 45(Q). Given that the Young's modulus
of the reinforcing member 37 is E.sub.f, a reinforcing-member
strain .epsilon..sub.f can be expressed by the following
expression. 8 f = f E f = Q f 2 E f Ht [ 11 ]
[0179] The result of an experimental test on the effect of the
above reinforcing member, and the performance of a structure member
having the reinforcing member installed thereon will be described
below. The test was carried out using an RC column (SRF-reinforced
model column) having the above reinforcing member installed thereon
and a non-reinforced RC column (non-reinforced model column) (SRF:
Soft Retrofitting for Failure). The outline of the test is shown as
follows.
[0180] An axial force and a repeated shear force are applied to the
column while constraining the rotation of the capital and base of
the column.
[0181] A horizontal force is applied to the capital through a rigid
frame having a loading point at the center of the column.
[0182] Under a displacement control, deformation angles of 1/400 to
4/400 are applied in the positive and negative displacements two
times, and then deformation angles of 6/400, 8/400, 16/400, 24/400,
32/400, 48/400 and 64/400 are applied in the positive and negative
displacements one time, and finally, a deformation angle of 200/900
as a limit of a pressure device is applied.
[0183] Fourteen cases were tested under a variable axial force and
a constant axial force. Among these cases, the results of nine
cases under a constant axial force were used to quantitatively
evaluate the performance of the above SRF reinforcing member. and
reinforcing bar acts on the structure member 31 (first and second
segmental members 33, 35) and the reinforcing member 37. Among the
shear forces, a first shear force to be transmitted from the upper
surface of the first segmental member 33 to the lower surface of
the second segmental member 35 through the reinforcing member 37 is
defined as a transmission shear force 49 (.DELTA.Q.sub.f). While
not shown, there is a second shear force to be transmitted in the
opposite direction of the first shear force or from the upper
surface of the second segmental member 35 to the lower surface of
the first segmental member 33 at the same value as that of the
first shear force.
[0184] Given that the tensile force 53 (.sigma..sub.cs) is 0 (zero)
for the purpose of simplifying the description without losing
universality, the difference between the shear forces in the upper
and lower surfaces of the first segmental member 33 provides the
transmission shear force 49 (.DELTA.Q.sub.f). The same goes for the
second segmental member 35.
[0185] Given that the thickness 47 (.DELTA.H) is infinitely small,
and a body force and a moment with an arm having a length in the
thickness direction are ignored. Further, given that there is no
distributed load, and the reinforcing member 37 bears only the
tensile stress 51 for the purpose of simplicity. Furthermore, given
that the transmission shear force 49 (.DELTA.Q.sub.f) acts to the
reinforcing member 37 such that the front-side and back-side
tensile stresses 51 (.sigma..sub.f) become equal to each other, and
.DELTA.Q/.DELTA.H is constant, the following relation is satisfied
in view of a balance expression: 9 f = Q f 2 H t [ 10 ]
[0186] wherein t is the thickness of the reinforcing member 37, and
Q.sub.f is a value derived by eliminating the shear forces
transmitted through concrete and reinforcing bar
[0187] FIG. 43 is a chart showing properties (test specifications)
of the tested columns, loading conditions, test results, and SRF
reinforcement effects, on the nine cases under a constant axial
force.
[0188] FIG. 10 is a graph showing the relationship between
horizontal load and deformation (restoring force characteristic) on
the non-reinforced model column (Case 8). The horizontal axis
represents a deformation (.delta. (mm)), and the vertical axis
represents a horizontal load (Q (kN)). In a deformation angle of
0.6% (1/166), a maximum load was increased up to 237 kH
(Q.sub.max), and the non-reinforced model column could not bear the
axial force (.eta.=0.3) in a cycle having a deformation angle of
greater than 1.5%.
[0189] FIG. 11 a graph showing the relationship between horizontal
load and deformation (restoring force characteristic) on the
SRF-reinforced model column (Case 9). The horizontal axis
represents a deformation (.delta. (mm)), and the vertical axis
represents a horizontal load (Q (kN)). The model column was
reinforced by bonding a reinforcing member formed of a polyester
woven fabric having a thickness (t) of 4 mm, around the model
column. The properties of the reinforcing member are shown in FIG.
43. The bonding strength is about 1 MPa.
[0190] In a deformation angle of 0.9%, a maximum load was increased
up to 258 kH (Q.sub.max), and the horizontal load is maintained at
a value of 80% (0.8 Q.sub.max) or more of a maximum horizontal load
until the deformation angle goes beyond 4.0%. Given that 0.8
Q.sub.max is a design ultimate state, an ultimate toughness
coefficient (p) is 6.
[0191] In the subsequent loading cycles, the peak load is gradually
reduced, and minimized (61: minimum point of the peak load) at a
deformation angle of 64/400. In the next cycle, the peak load is
increased.
[0192] FIG. 12 is a graph showing the relationship between the peak
value of the horizontal load and the deformation in each of the
loading cycles, on the nine cases under a constant axial force in
FIG. 43. The horizontal axis represents a deformation angle (R
(%)), and the vertical axis represents a maximum horizontal load
(peak load) in a positive direction in each of the loading cycles.
Numerals in the figure indicate the case numbers illustrated in
FIG. 43.
[0193] Referring to FIG. 11, in all of the reinforced cases (Cases
2, 3, 5, 9 and 13), a maximum point (maximum value Q.sub.max), a
minimum point (minimum value Q.sub.min) and an apparent
gradientchange point (Q.sub.mid: peak load at the change point) are
observed. For example, in Case 9, a maximum point 63, a minimum
point 65 and a gradient-change point 67 are observed. The Case 2
with a small reinforcement amount has a smaller R.sub.4
(deformation angle at the minimum point) than that of other
cases.
[0194] For each of these cases, Q.sub.mid/Q.sub.max and
Q.sub.min/Q.sub.max were calculated based on the above maximum
point, minimum point and gradient-change point. The result is shown
in FIG. 62. Q.sub.midQ.sub.max becomes approximately equal to a
theoretical value of 0.5 according to the expression [4]. Q.sub.min
is reduced from Q.sub.mid only by about 10% thereof. This result
supports the validity of the aforementioned quantification of the
effect of the reinforcing member.
[0195] FIG. 13 is a graph showing the relation between
structure-member circumferential-length elongation strain and
deformation. The horizontal axis represents a deformation angle (R
(%)), and the vertical axis of a structure-member
circumferential-length elongation strain (4) (%)). The measurement
was performed along five lines provided around the reinforced
columns at even intervals. As a result, all of the lines were
uniformly elongated, which supported the validity of the expression
[10]. The average values of the test results was plotted to prepare
FIG 13.
[0196] Referring to FIGS. 12 and 13, it is proved that the change
of a peak load and the change of a circumferential strain in each
of the cycles have an extremely strong correlation as with FIGS. 5
and 6 which have been schematically shown. That is, most of a shear
force after the maximum load Q.sub.max is borne by the reinforcing
member according to the mechanism which has been described in
conjunction with FIGS. 7 and 8.
[0197] In this way, the design calculation can be performed
according to the aforementioned quantification models of the
reinforcement effect and the performance of a structure member
having a reinforcing member installed thereon.
[0198] For the purpose of comparison, the index (reinforcement
efficiency) K representing the reinforcement effect, which is
defined by the following expression [12] according to a method of
Japan Society of Civil Engineers, was calculated under the
condition of a design ultimate state of 0.8 Q.sub.max:
S=S.sub.c+S.sub.s+KS.sub.s(A.sub.f,f.sub.fud) [12]
[0199] wherein S is a shear strength after reinforcement, S.sub.c
being a shear strength calculated from a concrete strength etc.,
S.sub.s being a shear strength calculated from a shear reinforcing
bar etc., and S.sub.s (A.sub.f, f.sub.fud) being a
reinforcing-member section A.sub.f and a reinforcing-member
strength f.sub.fud which are substituted with corresponding values
in a SRF reinforcing member. FIG. 62 shows the calculated K
(reinforcement efficiency).
[0200] Further, a design strength .sigma..sub.fd of the reinforcing
member was calculated back according to a method defined in the
design/installation manual for continuous-fiber reinforcement of
Architectural Institute of Japan. FIG. 43 shows the ratio
(reinforcement efficiency: .sigma..sub.fd/.sigma..sub.fmax) of the
design strength .sigma..sub.fd to a fracture strength
.sigma..sub.fmax of a SRF reinforcing member. In the above
calculation, a shear strength S after reinforcement was calculated
by determining a shear margin from a roughness coefficient. The
calculation was also performed on the assumption that a yield
deformation angle was 1/250 in all of the cases.
[0201] The reinforcement efficiencies in the both methods (K,
.sigma..sub.fd/.sigma..sub.fmax) are an approximately the same
value of about 0.2 in the case of F.sub.c=3.5 MPa. In the case of
F.sub.c=18 MPa, it is observed that the value tends to be
increased. In particular, this tendency is significant in the
latter method (.sigma..sub.fd/.sigma..sub.- fmax). This would
result from evaluating the reinforcement effect as the square root
of a reinforcement amount. On the reinforcement efficiency K, there
have been reported experimental values in the range of 0.8 to 1.0
for carbon fibers, and about 0.4 for aramid fibers.
[0202] In the above test, a small value or about 0.2 less than that
in the aforementioned conventional techniques and 1.0 in a
reinforcing bar is obtained. This results from the difference in
the material or a low Young's modulus of the reinforcing member,
and the methodological or structural difference or a mechanism
based on the peeling and displacement caused between the
reinforcing member and a substrate.
[0203] The result obtained by calculating the circumferential
strain in the design ultimate state (0.8 Q.sub.max) from an
actually measured circumferential length is shown in FIG. 62. An
actually measured ultimate circumferential strain (.phi..sub.2) is
in the range of 0.2 to 0.4%, and thus the damage level of the
inside of the structure member is equivalent to that in the
conventional techniques such as the reinforcement using carbon
fibers.
[0204] A reinforcing-member strain (.epsilon..sub.f) was calculated
from an actually measured shear load (Q) (see the expression [11]),
and then a constraint rate (a/L.sub.0) was calculated from the
calculated reinforcing-member strain (.epsilon..sub.f) and an
actually measured circumferential strain (.phi.)) (see the
expression [6]). This constraint rate (a/L.sub.0) is shown in FIG.
62. The constraint rate (a/L.sub.0) is the ratio of a free length
(a) to a circumferential length (L.sub.0).
[0205] In this test, the tested reinforced column receives a shear
force from one direction. For example, given that when a gap is
generated in a surface parallel to a direction of the shear force
and thereby a bonding constraint is completely released and shifted
to a geometrical constraint, two surfaces of the circumference of a
square section provide resistance, the constraint rate (a/L.sub.0)
is theoretically 0.5.
[0206] Referring to FIG. 43, the tested reinforced column has a
constraint rate (a/L.sub.0)<0.5 in Cases 3 and 5, and a
constraint rate (a/L.sub.0)>0.5 in Cases 9 and 13. Thus, it can
be said that in the design ultimate state, while a bonding
constraint in Cases 3 and 5 having a deformation angle R.sub.2 of 1
to 2% is still effective, a bonding constraint in Cases 9 and 13
having a deformation angle R.sub.2 of 4 to 6% is released and
completely shifted to a geometrical constraint.
[0207] As in the above observation on the test results, the
validity of the model for the effect of a reinforcing member
(reinforcement effect model) and the model for the performance of a
structure member with a reinforcing member installed thereon
(structure-member performance model) has been verified. It is
understood that the aforementioned numerical values are
experimental values, and a safety factor coping with variations
must be used in actual designs.
[0208] A method for determining the material, thickness,
installation range and others (or for designing) of the reinforcing
member of the present invention will be described below.
[0209] FIGS. 39 and 40 are design flowcharts for a reinforcement
amount in a process of reinforcing a structure member through a
method of the present invention. With reference to the flowcharts
in FIGS. 39 and 40, a method of determining reinforcement
parameters will be described below.
[0210] As shown in FIG. 39, limit conditions of the weight, shape,
function and others of a structural body are first determined (Step
301). Concurrently, the amplitude, cycle or period, duration and
energy of a sudden external force likely to act on the structural
body are determined (Step 302). Among the sudden external force
likely to act on the structural body, a burden share to be borne by
a substrate of the structural body, such as reinforcing bar and
concrete, is also determined (Step 303).
[0211] Then, in a design process (a) of determining parameters of a
structure member when a structural body or a structure member is
newly constructed, the parameters of the structure member are
determined in consideration of the data determined in Steps 301 to
303 (Step 304). The parameters of the structure member may be
determined using conventional structural design/calculation methods
or any other suitable reinforcement manuals.
[0212] Then, Among each of a load in ordinary condition, such as
the weight of the structure member itself, and the sudden external
force, a burden share to be borne by a method of the present
invention is determined (Step 305). Specifically, this step is
intended to determine the type, property, and magnitude (amplitude,
period, duration, and energy) of the sudden external force to be
borne by the method, structure or material of the present
invention. These data may be obtained by subtracting the energy of
a sudden external force bearable with other factors than the
reinforcement according to the method of the present invention (the
burden share of the substrate etc. determined in Step 303) from the
total energy of the sudden external force likely to act on the
structural body in the durable term thereof, which has been
determined in Step 301. Thus, if the reinforcement of the present
invention is used in a structural design for a new construction,
the materials and/or parameters of a structure member can be
determined in an economically advantageous manner by a factor of
the reinforcement of the present invention.
[0213] In a design process (b) involving no determination of any
parameter of a structure member, for example, in a design process
of reinforcing an existing structural body or structure member
using the reinforcing member, the data in Step 305 are determined
from the data determined in Steps 302 and 303. In this process,
such data may be obtained by subtracting a sudden external force
bearable with other factors than the reinforcement according to the
method of the present invention from the total energy of the sudden
external force likely to act on the structural body in the durable
term thereof, as with the process (a).
[0214] Then, the amplitude and energy of a sectional force to act
on the structure member are calculated (Step 306). Specifically,
based of the type, property and magnitude of the sudden external
force determined in Step 302, the amplitude and magnitude of a
sectional force (shear force, axial force, bending moment, etc.) to
act on a structure member including a reinforced structure member
and other structure members, and a deformation (shear strain, axial
strain, bending strain, etc.) of the structure member.
Concurrently, the displacement amplitude and vibrational energy of
the entire structure body to be induced by the sudden external
force are calculated (Step 307).
[0215] The data in Step 306 or 307 may be rigorously calculated by
performing a structural analysis calculation, such as a finite
element method or frame analysis method taking account of a
restoring force characteristic of a reinforced structure member and
other structure members as shown in FIG. 51. Alternatively, the
data in Step 306 or 307 may be calculated by simplifying a
structural system and setting assumptions such as energy formulas,
as in practical structural designs. Except that an associated
deformation range is wider than that in a conventional calculation,
the calculations in Steps 306 or 307 can be performed in the same
manner as that in a structural design for a structure member having
a known restoring force characteristic.
[0216] Then, the relationship of a reinforcement amount, a
restoring force characteristic and an axial strain of the
reinforced structure member is determined (Step 308). The data in
Step 308 are determined by the calculations in Steps 306 and 307.
In Step 308, it is generally required to perform a feedback from
310 to Steps 306 and 307 through Steps 308, as indicated by the
dashed lines of FIG. 59.
[0217] Then, limit conditions of the function, usability,
recoverability and others of the structural body after the action
of the sudden external force such as a seismic force are determined
(Step 309), and the determined limit conditions are compared with
the displacement amplitude and vibration energy of the structural
body calculated in Step 307 to determine reinforcement parameters
(Step 310).
[0218] Specifically, the reinforcement parameters are determined by
comparing the deformation of the structural body calculated in
Steps 306 to 308 with an allowable deformation amount to be derived
from the conditions determined in Step 309 or the use conditions of
the structural body after the action of the sudden external force
such as a seismic force. Step 310 is performed in consideration of
the limit conditions of the weight, shape, function and others of
the structural body which have been determined in Step 301.
[0219] If the conditions in Step 309 are determined based on the
policy of simply preventing collapse against a large earthquake,
the allowable deformation can be set at a large value. If a large
deformation involves the risk of disaster such as derailment even
immediately after occurrence of a large earthquake, as in an
elevated railroad for the bullet train, the reinforcement amount
will be determined in consideration of such a factor.
[0220] Further, if a design ultimate state is defined by a
load-withstanding capacity (strength) corresponding to a given
deformation angle of a structure member, the reinforcing member can
be designed by the following process.
[0221] <1> Among a shear strength Q.sub.u expected to a
structure member in a design ultimate state, a shear strength
Q.sub.fu to be shared by the reinforcing member is determined.
[0222] <2> A allowable damage in the structure member is
expressed by the total value du of a gap width on the circumference
of the structure member, and the value du is converted into a
reinforcing-member strain .epsilon..sub.fu.
[0223] <3> A reinforcement amount (thickness t) is calculated
from Q.sub.fu, .epsilon..sub.fu, a stress distribution in the
inside of the structure member and a Young's modulus of the
reinforcing member E.sub.f.
[0224] In the above Steps <1> to <3>, the expressions
[5] to [11] or modified expressions obtained by modifying the
expressions [5] to [11] according to the conditions of the
structure member. In this case, the reinforcement design has to be
performed using a sufficient safety factor for a fracture strain
because there is a possibility of causing a strain several times
larger than the reinforcing-member strain .epsilon..sub.f in the
expression [11]. Further, in the calculation of Q.sub.f, a shear
force transmitted by a substrate (a shear force transmitted by
concrete, reinforcing bar or the like, etc.) may be subtracted, or
the subtraction of this shear force may be set at 0 (zero) on the
safe side.
[0225] A load-withstanding capacity of the structure member after
the structure member goes beyond the above design ultimate state
can also be calculated using the expressions [8] and [9]. However,
in an actual design, the performance of the structure member and
the reinforcement amount are experimentally checked as needed as in
a conventional design for reinforced concrete members.
[0226] The expressions [5] to [11] are valid even if the substrate
is not a structural material such as concrete. Therefore, a
structure member can be produced using a substrate consisting of a
material, such as brick or block, which has been considered as a
non-structural material, However, if the rigidity of a substrate is
less than that of the reinforcing member, the deformation of the
substrate will be increased before development of a reinforcement
effect, and a design process including a calculation required for
taking account of the increase deformation will be complicated as
compared to the above process. Thus, the material of the
reinforcing member is selected such that the Young's modulus of the
reinforcing member is less than that of the substrate, as described
above. However, if the Young's modulus of the reinforcing member is
excessive low, the thickness of the reinforcing member required for
obtaining a desired reinforcement effect will be increased as shown
in the expressions [3] and [11]. Specifically, the material of the
reinforcing member is selected from one having a Young's modulus
preferably in the range of about 1/2 to 1/20, more preferably about
1/5 to 1/10, of that of the substrate.
[0227] The bonding constraint mechanism becomes effective for a
larger gap and can suppress the deformation (circumferential
strain) of the substrate at a smaller value as the reinforcing
member has a larger Young's modulus in the design ultimate state.
This deformation (circumferential strain) of the substrate is
quantified by the expressions [3] and [11].
[0228] FIG. 9 is a graph showing a stress-strain relationship of
the reinforcing member. The horizontal axis represents a strain
(.epsilon.) of the reinforcing member, and the vertical axis
represents a stress (.sigma..sub.f) of the reinforcing member. As
described above, the reinforcing member is required to have
extensibility (large fracture strain). In this regard, the design
for the reinforcing member and others is preferably performed in
consideration of the curve of the stress-strain relationship as
shown in FIG. 9.
[0229] Preferably, on the curve of the stress-strain relationship
in FIG. 9, the ratio 59 (.sigma..sub.fu/.epsilon..sub.fu) of a
stress a fu of the reinforcing member to .epsilon..sub.fu of the
reinforcing member in a design ultimate state 57 of a structure
member is defined as a Young's modulus E.sub.f of the reinforcing
member in the design ultimate state, and the design of the
reinforcing member and others is performed using the Young's
modulus E.sub.f, and a fracture strain .epsilon..sub.max and
fracture stress (strength) .sigma..sub.max of the reinforcing
member The reinforcing member is selected to satisfy a desired
performance of the reinforced structural with reference to the
expressions [1] to [9]. When a polyester woven fabric or the like
is used as the reinforcing member, it may be heated to provide a
tensile force thereto, and then cooled while maintaining the
tensile force or subjected to a treatment for impregnating the
reinforcing member with resin (resin impregnation treatment), to
provide E.sub.f larger than .sigma..sub.fu/.epsilon..sub.f- u. The
reinforcing member subjected to the above treatment can have a
higher reinforcement efficient (reinforcement effect per unit
thickness) than that of the reinforcing member without the
treatment, to achieve a reduced material cost.
[0230] A reinforced structure will be described below in
conjunction with an example where a structure member is a walled
column. FIG. 14 is a perspective view of a walled column with the
reinforcing member installed thereon. The walled column comprises a
column 71 and a wall 73. The reinforcing member 75 is installed in
such a manner it is wound around the column 71 and bonded on a
reinforcing-member installation range 79. The reinforcing-member
installation range 79 has a larger area than that of an effective
bonding constraint range 77. The effective bonding constraint range
77 corresponds to a given constraint length (b). The wall 73 is
formed with no through-hole for installing the reinforcing member
75.
[0231] An epoxy-urethane based one-component adhesive (bonding
strength T.sub.f=1 MPa) is used for the bonding. A polyester sheet
member (Young's modulus E.sub.f=2100 MPa, thickness t=2 mm) is used
as the reinforcing member 75.
[0232] Given that a shear force applied in X direction causes a gap
in a surface parallel to X direction, a restraint length (b)
allowing the bonding constraint to be effectively maintained until
the total (d) of the gap width measured along a circumferential
length parallel to X axis is increased up to 2 mm is calculated as
b=1183 mm according to the expression [3]. Given the a safety
factor is 2, a design constraint length (bd) is about 40 cm.
[0233] FIG. 15 is a sectional view of the walled column 69 in FIG.
14. The design constraint length (b.sub.d) corresponds to the
effective bonding constraint range 77 in FIGS. 14 and 15.
[0234] While a shear bearing force of the walled column 69 is
obtained by assigning the dimensions of the column 71, the strength
of the reinforcing member 75, the strength of the adhesive and
others to the expressions [4] and [10], it is desired to
experimentally check it as needed because the reinforcement effect
and the geometrical restraint limit are different from those in
case where the reinforcing member is fully wound around the
column.
[0235] A restoring force characteristic in the state after the
shear force goes beyond the design ultimate state to cause fracture
of the walled column 69 and thereby the bonding restraint is
completely released and shifted to the geometrical restraint can be
calculated according to the expressions [8] an [9].
[0236] In this state, at the joint portion between the column 71
and the wall 73, the stress af of the reinforcing member 75 is
transmitted through the inside of the substrate. Thus, the limit
((Q.sub.max2, R.sub.5): FIG. 5) of the validity of the geometrical
restraint is determined by smaller one of the strength of the
reinforcing member and the strength of the substrate at the joint
portion. At any rate, the geometrical restraint can be maintained
up until the limit (Q.sub.max2, R.sub.5) without forming a hole or
the like in the walled column 69 and penetrating the reinforcing
member therethrough.
[0237] FIG. 16 is a sectional view of the walled column 69 in FIG.
14. While the reinforcing member 75 installed around the column 71
is opened at the joint plane between the column 71 and the wall 73,
a portion of the column 71 in this open zone 183 is constrained by
the wall 73 having the reinforcing member 75 installed thereon.
Thus, the entire circumferential of the column 71 is constrained by
the reinforcing member 75 and the wall 73 having the reinforcing
member 75 installed thereon. In this case, the geometrical
constraint is achieved in an effective geometrical constraint range
81.
[0238] Alternatively, a given reinforcement effect can be obtained
by installing the reinforcing member on only one of the surfaces of
a structure member such as wall. Further, a earthquake-resisting
wall may be formed by placing a pair of boards, such as precast
concrete boards, in parallel with one another between two existing
columns to form a wall, pouring concrete or filling sands or the
like into the space between the boards, and installing the
reinforcing member around the wall and/or the columns.
[0239] Thus, according to the above reinforced structure, the
reinforcing member having a given rigidity and extensibility is
installed a portion of the surface of a structure member to be
reinforced, to reinforce the structure member. Thus, the
reinforcement can be applied to a structure member having any shape
such as a convexo-concave or irregular shape. In addition, the
reinforcing member can be installed without forming any hole or the
like in a structure member subject to reinforcement. Therefore, a
reinforced structure excellent in toughness and load-withstanding
capacity can be constructed quickly and readily at a low cost.
[0240] Further, the reinforcement effect of the reinforcing member
and the performance of the reinforced structure with the
reinforcing member can be quantified and/or evaluated according to
the aforementioned reinforcement effect model and structure-member
performance model. Thus, the reinforcing member can be adequately
selected and designed depending on a structure member subject to
reinforcement.
[0241] As seen in the reinforcement effect model and the
structure-member performance model, the reinforcing member and the
adhesive according to the first mode of embodiment can be
effectively selected depending the material, category and type
(existing or new construction, etc.) of a structure member. Thus,
the labor load and cost for constructing the reinforced structure
having a desired performance and preparing/installing the
reinforcing member having a desired reinforcing effect or
quake-resistance effect can be constructed can be reduced while
shortening a construction period.
[0242] As a substitute for the reinforcing member 75, a
strip-shaped polyester belt 199 as shown in FIG. 21 may be used.
The material of the polyester belt 199 may be polyester-based
fibers for use in bell rope or the like. While a reinforcing sheet
such as a construction sheet has a strength in the range of 500 to
1000 kgf/3 cm width, the polyester belt 199 has a strength of about
15000 kgf/5 cm width.
[0243] Another reinforced structure will be described below in
conjunction with an example where a structure member has an H
shape. FIG. 17 is a perspective view of an H-shaped structure
member 143 after reinforcement. As shown in FIG. 17, the H-shaped
structure member 143 is reinforced using a reinforcing member 145
and a granular filler material 147.
[0244] The sheet-shaped reinforcing member 145 is shaped into a
cylindrical shape and disposed around the H-shaped structure member
143 to form a space therebetween. The granular filler material 147
is filled in the space between the H-shaped structure member 143
and the reinforcing member 145. For example, a fiber or
rubber-based sheet material may be used for the reinforcing member
145. For example, the filler material 147 may be a natural granular
material, such as sands, or an artificial granular material, such
as resin.
[0245] The glandular filler material 147 transmits a stress to the
reinforcing member 145 while being deformed in connection with
energy loss. Thus, differently from the conventional reinforcing
techniques such as continuous fibers or steel-plate wrapping, there
is no need for fixing the filler material with resin or adhesive.
Even if the filler material is bonded or fixed for the reason of
construction, the bonding or fixation may be performed in a
temporary level allowing the shape of the filler material to be
held under ordinary loading or in earth tremor.
[0246] This type of reinforced structure may be used to reinforce a
structure member having a complicated sectional shape, as well as
the H-shaped structure member 143. In this type of reinforced
structure, when the structure member is deformed in connection with
an apparent volume expansion, the granular filler material 147
transmits the apparent volume expansion to the reinforcing member
to provide enhanced reinforcement effect. Further, the granular
filler material may be formed of an inorganic noncombustible
material having high heat capacity to have an additional effect of
protecting the H-shaped structure member 143 from heat.
[0247] Still another reinforced structure will be described below
in conjunction with an example where a structure member is hollow.
FIG. 18 is a perspective view of a hollow structure member 149
after reinforcement. As shown in FIG. 18, the hollow structure
member 149 is reinforced using a reinforcing member 145 and a
granular filler material 147.
[0248] The sheet-shaped reinforcing member 145 is installed on and
around the outer surface of the cylindrical hollow structure member
148. The inside of the hollow structure member 149 is filled with
the granular filler material 145. For example, a fiber or
rubber-based sheet material may be used for the reinforcing member
145. For example, the filler material 147 may be a natural granular
material, such as sands, or an artificial granular material, such
as resin.
[0249] The granular filling material 147 is installed to fill the
space of the hollow structure member 149. In addition, the
glandular filler material 147 transmits a stress to the reinforcing
member 145 while being deformed in connection with energy loss.
Thus, there is no need for solidifying the filler material filled
in the inside of the structure member as in concrete used in a
concrete-filling steel-pipe construction method.
[0250] In this reinforced structure, when a hollow structure member
is reinforced, the granular filler material 147 is installed inside
the structure member to provide enhanced reinforcement effect. The
filler material acts to transmit to the reinforcing member 145 an
apparent volume expansion cased when the hollow structure member
149 is fractured in connection with energy loss. While the hollow
structure member in the above example has a circular sectional
shape, the present invention is not limited to such a shape.
[0251] In addition, in order to reinforce the H-shaped structure
member 143 or the hollow structure member 149 used the glandular
filler material 147, compounding this reinforced structure and
other reinforced structure can be applied.
[0252] Next, an example of the reinforced structure in case of
using plurality of reinforcements will be described. FIG. 19 is a
partial sectional view of a reinforced member 181. In FIG. 19, the
member 181 is reinforced by use of a protective reinforcement 183,
a reinforcement 185, a reinforcement 187, and a protective
reinforcement 189.
[0253] The protective reinforcement 183, the reinforcement 185, the
reinforcement 187, and the protective reinforcement 189 are
sequentially, from inside to outside, disposed on the member 181.
The protective reinforcement 183 is disposed in order to protect
the reinforcements 185 and 187 and the protective reinforcement 189
from the action of the member 181. For example, when the member 181
is made of a material, such as concrete, from which alkali separate
outs, and the reinforcements 185 and 187 and the protective
reinforcement 189 are made of a material, such as polyester fiber,
of low alkali resistance, the protective reinforcement 183 is made
of a material, such as a resin, which has a function to prevent
separation of alkali from the member 181.
[0254] The protective reinforcement 189 is disposed in order to
prevent a deterioration in the function of the protective
reinforcement 183 and the reinforcements 185 and 187 which would
otherwise result from the action of substances in the external
environment. For example, when the protective reinforcement 183 and
the reinforcements 185 and 187 are polyester-fiber sheets or the
like, these reinforcements are likely to be deteriorated by
ultraviolet rays. Thus, the protective reinforcement 189 is made of
epoxy, urethane, or a like resin to thereby prevent a deterioration
of the reinforcements disposed inside the same. A fireproof belt
can also be used as the protective reinforcement 189.
[0255] The reinforcement 185 and the reinforcement 187 differ in a
reinforcement effect on the member 181. For example, the
reinforcement 187 is made of polyester fiber or the like, and the
reinforcement 185 is made of a resin or fiber impregnated with
resin. In this case, the reinforcement 187 exhibits a reinforcement
effect at up to a large strain (up to about 15%) of the member 181,
whereas the reinforcement 185 exhibits a reinforcement effect at a
low strain (not greater than 1%) of the member 181.
[0256] When the member 181 is to be reinforced merely by use of a
polyester fiber reinforcement, the reinforcement must assume a
large thickness in order to exhibit a reinforcement effect at the
stage of a small strain of the member 181, since the reinforcement
is smaller in Young's modulus than the member 181. However, through
combined use of the polyester fiber reinforcement and a
reinforcement made of a material, such as a resin or fiber
impregnated with resin, having a large Young's modulus, the
polyester fiber reinforcement thinner than that used solely for
reinforcing the member 181 can exhibit a reinforcement effect even
at a small strain (not greater than 1%) of the member 181. Also,
being bonded directly to the surface of the member 181 or
protective reinforcement 183, the reinforcement 185 can exhibit a
reinforcement effect at small strain. The protective reinforcement
183 assumes, as needed, a function for transmitting a shear force
induced between the surface of the member 181 and the reinforcement
185. For example, a resin primer is used as the protective
reinforcement 183.
[0257] The reinforcement 185 and the reinforcement 187 may differ
in a mechanism for yielding a reinforcement effect so as to exhibit
a reinforcement effect under different load conditions and over the
range of deformation. For example, there are combined a method in
which part of a shear force imposed on the member 181 is directly
borne by a reinforcement, and a method in which the expansion of an
apparent volume of the member 181 is restrained.
[0258] Material and configuration of the reinforcement 187 can be
such that a reinforcement effect is yielded through restraint of
the expansion of an apparent volume. With the aim of enhancing the
load bearing capacity of the member 181 through enhancement of
shear fracture yield strength of the member 181, the reinforcement
185 is made of an iron plate, carbon fiber, aramid fiber or the
like. Through direct transmission of a shear force between the
member 181 and the reinforcement 185, the shear force is shared
between the member 181 and the reinforcement 185, whereby the
member 181 is reinforced. Also, a polyester sheet or belt or the
like whose rigidity is enhanced through impregnation with resin or
through application of adhesive to the entire surface thereof can
be used as the reinforcement 185. This yields a merit in that the
reinforcement 185 and the reinforcement 187 can be continuously
laid.
[0259] FIG. 20 is a graph showing the relationship between load and
deformation with respect to the member 181 which is reinforced by
means of a multilayer configuration as shown in FIG. 19. In FIG.
20, the vertical axis represents load, and the horizontal axis
represents deformation. The load represents section forces of the
member 181, such as axial force, bending moment, shear force, etc.
The deformation represents deformations corresponding to the
section forces; specifically, axial contraction, flexural modulus,
shearing strain, etc. A curve 193 which represents the case of
reinforcement by means of multilayer configuration indicates that
the member 181 has load bearing capacity over a wider range of
deformation as compared to the case of no reinforcement employed as
represented by a curve 191.
[0260] FIG. 20 shows an ordinary example in which the effective
deformation range of the reinforcement 185 does not overlap with
that of the reinforcement 187; i.e., a slight reduction in load
bearing capacity occurs between an effective range 195 of the
reinforcement 185 and an effective range 197 of the reinforcement
187. The reduction of load bearing capacity can be avoided by
overlapping the effective deformation ranges of the reinforcements
185 and 187.
[0261] According to this reinforced structure, reinforcements of
different characteristics are disposed in layers on the exterior of
a member, to thereby exhibit a reinforcement effect over a wide
range of load conditions of the member as well as over a wide range
of conditions of the external environment. The member 181 is not
limited to a concrete member or the like but may be the filler 147
shown in FIGS. 17 and 18. In this case, through employment of the
filler 147 that yields an effect equivalent to that yielded by the
protective reinforcement 183, the protective reinforcement 183 may
be omitted.
[0262] Notably, a beltlike reinforcement of high strength and
rigidity, such as the polyester belt 199, can be used as the
reinforcement 185 to be bonded directly to the surface of the
member 181 or protective reinforcement 183. Since the polyester
belt 199 can be woven into texture that exhibits greater Young's
modulus per unit width as compared with a polyester sheet, the
polyester belt 199 can be used as the reinforcement 185, which
exhibits a reinforcement effect at the stage of small strain. For
example, according to the tensile test result of the polyester belt
199 having a width of 64 mm and a thickness of 4 mm, strain is 2%
under a load of 2500 kgf.
[0263] When the polyester belt 199 is used as the reinforcement
185, a column 205 shown in FIGS. 22 to 25 corresponds to the member
181 of FIG. 19. A reinforcement method by use of the polyester belt
199 as shown in FIGS. 22 to 25 will be described in the subsequent
section of an eighth embodiment.
[0264] FIG. 21 is a plan view of the polyester belt 199; FIGS. 22
and 23 are perspective views showing examples of the column 205
reinforced by use of a beltlike reinforcement 201; and FIG. 24 is
an elevation of the column 205 shown in FIG. 23.
[0265] First, reinforcement shown in FIG. 22 will be described. In
FIG. 22, a plurality of beltlike reinforcements 201 are disposed at
predetermined intervals on the column 205 in such a manner as to be
wound about the column 205. End portions of each of the beltlike
reinforcements 201, which are wound about the column 205, can be
connected together by means of bonding and/or a clasp, which are
mechanical joints. Use of mechanical joints can implement
reinforcement in a short period of time and is thus suited for
urgent reinforcement to be performed immediately after an
earthquake disaster. Beltlike reinforcements 203 bonded axially to
the column 205 can be expected to yield the effect of controlling a
crack(s) extending along a direction intersecting the same.
[0266] Next, reinforcement shown in FIGS. 23 and 24 will be
described. The beltlike reinforcement 201 is compactly wound about
the column 205 shown in FIGS. 23 and 24. While tension is imposed
on the beltlike reinforcement 201 in the direction of arrow C, the
beitlike reinforcement 201 is wound onto the column 205 in the
direction of arrow D, thereby enhancing a reinforcement effect. The
beltlike reinforcement 201 is bonded directly to the column 205.
Comer portions of the column 205 are not particularly required to
be chamfered or to undergo like processing in order to avoid
breaking textile at the corner portions. However, a beltlike
reinforcement (not shown) bonded to a corner portion of a member in
parallel with the edge of the corner portion can be expected to
yield the effect of easing stress concentration of an edge portion
on a reinforcement.
[0267] As shown in FIG. 24, the beltlike reinforcement 201 is wound
onto an upper end portion 207 and lower end portion 211 of the
column 205 in parallel with the circumferential direction of the
column 205 and is spirally wound onto a general portion 209 such
that, as the beltlike reinforcement 201 is wound one turn, it
axially advances by the width thereof, whereby the beltlike
reinforcement 201 can be wound about the column 205 compactly and
evenly. Also, the winding direction (clockwise or counterclockwise)
can be altered so as to wind the beltlike reinforcement 201 onto
the column 205 in two layers, three layers, etc., thereby enhancing
a reinforcement effect. In this case, after winding of the first
layer is completed, an adhesive is applied to the first layer, and
then the second layer is formed through winding such that the
winding pitch is shifted by half the width of the beltlike
reinforcement 201 between the first and second layers, thereby
preventing the potential move of the beltlike reinforcement
201.
[0268] In order to allow the reinforcing member to be in close
contact with the substrate in the above winging manner, it is
required that the reinforcing member can be bent at an angle equal
to or greater than the corner angle of the column, and sheared at
an angle equal to or greater than the displacement angle between
the parallel winding and the spiral winding. In a typical column,
the bending angle and the displacement angle are 90 degree or less
and 2-degree or less, respectively. When a reinforcing member is
installed in a crossed manner as described later in connection with
FIG. 56, it is preferable that the reinforcing member can be
sheared at a large angle.
[0269] FIG. 25 is a sectional view of a surface portion of the
column 205 shown in FIGS. 22 to 24. As shown in FIG. 25, the
beltlike reinforcement 201 is bonded directly to the column 205 by
use of an adhesive 213.
[0270] The beltlike reinforcement 201 shown in FIGS. 22 to 25 is,
for example, the polyester belt 199 shown in FIG. 21. As mentioned
in the sections of the second and seventh embodiments, the
polyester belt 199 is made of polyester fiber, which is a material
for a strap or the like. The polyester belt 199 is used
particularly in view of the following: being higher in rigidity and
strength than a civil engineering sheet, the polyester belt 199
restrains an increase in the width of crack in the column 205 and
controls the deformation of an apparent volume for the range of
small strain.
[0271] Next will be described the method for calculating the amount
of reinforcement in the case of reinforcement for restraining the
width of crack for the range of small strain of the column 205.
FIG. 26 is a view showing an effective bond length between the
beltlike reinforcement 201 and a crack 215.
[0272] When a member is locally ruptured due to bending, axial
force, shear force, or a like force imposed thereon, the crack 215
appears on the surface of the member. In FIG 126, the crack 215 is
made on the surface of the column 205, to which the beltlike
reinforcement 201 is bonded directly. The belt width 219 of the
beltlike reinforcement 201 is w. A force which attempts to expand
the crack 215; i.e., tension 221, is imposed on the beltlike
reinforcement 201 in the amount of q per belt. In FIG 145, the
beltlike reinforcement 201 restrains crack width 217 to d or
less.
[0273] Stress concentration is present in the vicinity of the crack
215. Width 223 (a) extending in opposite directions from the crack
215 is the length of a region where a bonding effect is lost due to
shear fracture of the adhesive 213 or member surface. Width 223 (a)
is hereinafter called a free length. Restraint length 225 (b) is a
natural restraint length of the column 205 and is measured from a
free end. Accordingly, the beltlike reinforcement 201 is bonded to
the column 205 along fixation length s=b-a.
[0274] Restraint length 225 is the length of a single side in the
case a rectangular cross section, as in the column 205, and is the
length of an arc corresponding to a central angle of about 90
degrees in the case of a circular cross section. When these lengths
are significantly large as compared with belt width 219 (w) of the
beltlike reinforcement 201, restraint length 225 is a length along
which an effective bonding force is not zero.
[0275] When the crack 215 is located at around the center of a
certain surface of a member having a rectangular cross section,
restraint length 225 extends to another surface of the member.
[0276] When k represents the rigidity of the beltlike reinforcement
201, free length a; i.e., width 223, crack width 217 (d), and
tension 221 (q) are related as expressed by
q=kd/a 21)
[0277] when .tau. represents the average shear force between the
beltlike reinforcement 201 and the column 205 as measured within
fixation length s=b-a, .tau. is expressed by
.tau.=q/(w.multidot.s) 22)
[0278] When free length a is eliminated from Eq. 21) and Eq. 22),
tension 221 (q), average shear force T, and crack width 217 (d)
hold quadratic relation as represented by
q=1/2[.tau.wb.+-.{(.tau.wb).sup.2-4.tau.wkd}.sup.0.5] 23)
[0279] This relation has two solutions q at maximum crack width
d.sub.max or less. Since a larger solution is first realized, the
larger solution is employed. Then, q falls somewhere between
maximum value q.sub.max and minimum value q.sub.min according to
crack width 217 (d).
q.sub.max=.tau.wb 24)
q.sub.min=0.5.tau.wb 25)
[0280] Crack width d.sub.max corresponding to minimum value
q.sub.min is expressed by
d.sub.max=.tau.wb.sup.2/(4k) 26)
[0281] When the crack width is in excess of d.sub.max, Eq. 23) does
not have a solution. That is, such a mechanism does not hold true.
Maximum value q.sub.max and minimum value q.sub.min when the
beltlike reinforcement 201 bears part of a force attempting to
expand the crack 215 are obtained from the above relations, thereby
enabling design of structural reinforcement through utilization of
the above-mentioned mechanism. Values obtained from Eq. 24) to Eq.
26) are proportional to bonding force T (average shear force)
between a member, such as the column 205, and the beltlike
reinforcement 201.
[0282] When a material which is inexpensive and has excellent
stretchability, such as the polyester belt 199, is used as the
beltlike reinforcement 201, since the Young's modulus of the
material is about one-tenth that of concrete or one-hundredth that
of iron, the following problem is involved. Even when the adhesive
213 having large average shear force .tau. is used for bonding, the
material encounters difficulty in sharing with a member a force
which is elastically imposed on the member, without formation of
the crack 215. However, when a reinforcement effect is particularly
needed at the stage of small deformation, a polyester belt or the
like is impregnated with resin to thereby enhance the rigidity of
the reinforcement. The thus-prepared reinforcement is used together
with an epoxy resin adhesive.
[0283] The polyester belt 199 has a woven body of a weft double
weave using a polyester-fiber yam with 1700 dtex (dcitex). The
polyester belt 199 has a Young's modulus of 4676 MPa, a thickness
of 4 mm, a fracture strain of 15%, and a specific gravity of 0.98.
Since the polyester base yam has a specific gravity of 1.4, a void
ratio of the polyester belt 199 is (1.4/0.98=) 1.43 when expressed
by the ratio of specific gravity.
[0284] The column 205 is made of reinforced concrete. Concrete has
a compression fracture strength of 13.8 MPa (135 kgf/cm.sup.2), a
Young's modus of 19500 MPa, and a direct shear strength of about
2.6 MPa. The reinforcing member was installed without performing
any chamfering and any adjustment of surface unevenness.
[0285] Rubiron 101 (one-component: available from Toyo Polymer Co.)
was used as an adhesive. The layer of the adhesive is 1 mm. The
adhesive has a bonding strength of about 1 MPa (10 kgf/cm.sup.2),
and a specific gravity of 1.4. A part of the adhesive is
infiltrated into the texture of the polyester belt 199, and cured.
However, even if the entire adhesive of 1 mm thickness enters into
the void of the polyester belt 199, it will occupy only about 70%
of the void of the polyester belt 199, and the breathability or
air-permeability of the reinforcing member can be maintained. While
Rubiron 101 is not a non-solvent adhesive, it has been
experimentally verified that the same reinforcement effect can be
obtained even using a non-solvent adhesive having a bonding
strength equivalent to that of Rubiron 101.
[0286] With respect to the effect of the reinforcement using the
impregnated aramid fibers as disclosed in the aforementioned
Japanese Patent Laid-Open Publication No. 8-260715, a test result
of the same method as that in FIG. 29 is introduced in a number of
publications. However, none of these publications reports the
increase of load after Q min, as indicated by the load-deformation
curve 243 b in FIGS. 30 and 50, and the test ends up with the
fracture of the aramid-fiber reinforcing member before Q min or the
peeling of the reinforcing member from a structure member.
[0287] A case study is conducted for the structure of FIG. 25
under, for example, the following conditions: the beltlike
reinforcement 201 is the polyester belt 199 having a width of 64 mm
and a thickness of 4 mm; the column 205 is a reinforced-concrete
column having a restraint length 225 of b=30 cm; and the adhesive
213 is LUBIRON, which is the trade name of an epoxy urethane
adhesive produced by Toyo Polymer Corp. In this study, calculation
conditions are as follows: average shear force T=10 kgf/cm.sup.2;
the beltlike reinforcement 201 (polyester belt 199) has a belt
width 219 of w=6.4 cm and a restraint length 225 of b=30 cm; and
the beltlike reinforcement 201 (polyester belt 199) has a rigidity
of k=153000 kgf/cm.sup.2.
[0288] Calculation of maximum value q.sub.max, minimum value
q.sub.max, and maximum crack width d.sub.max by use of Eq. 4) to
Eq. 6) gives the following results: maximum value q.sub.max=1920
kgf; minimum value q.sub.min=960 kgf; and maximum crack width
d.sub.max=0.12 cm.
[0289] Accordingly, when this reinforcement is carried out,
cracking can be restrained up to maximum crack width d.sub.max=1.2
mm. A single beltlike reinforcement 201 (polyester belt 199) bears
a tension 221 of q=0.9 tf.
[0290] FIG. 27 is a schematic view of the column 205 subjected to
an axial force, bending, and a shear force. FIG. 28 is a view
showing a force which attempts to expand the crack 215 formed in
the column 205. Described below is a reinforcement effect to be
yielded in the case where the column 205 is reinforced by use of
the polyester belt 199, which serves as the beltlike reinforcement
201, according to the method of FIG. 24; and the thus-reinforced
column 205 is loaded in the following manner: while axial force 229
(P) is applied to the column 205, a horizontal force is applied to
the column 205 so as to repeatedly generate bending moment 231 (M)
and shear force Q.
[0291] The column 205 is assumed to be an ordinary structural
column. Conditions of study are as follows: shear force 227 (Q) is
horizontally imposed on the column 205 at the middle of height h;
i.e., at height (h/2); and the upper and lower ends of the column
205 slide horizontally without involvement of rotation. As a
result, a horizontally even shear force (resultant force Q) and an
axial force (resultant force P) are generated in the column 205. A
bending moment is M=Qh/2 at the upper end of the column 205, zero
at the middle, and -M at the lower end.
[0292] When shear force 227 (Q) reaches maximum shear force
Q.sub.max, which depends on the conditions of reinforcing bars and
concrete of the column 205, the crack 215 is generated in a
direction of angle .theta. 237. A force which attempts to
horizontally expand the crack 215 is shear force 227 (Q) imposed on
the column 205. The force is considered to be borne by the beltlike
reinforcement 201 which is present over the range represented by
arrow c 233. Since a single belt of the beltlike reinforcement 201
has a width of w and exhibits a tension of q, a resultant force Q
of the beltlike reinforcement 201 present over the range
represented by arrow c 233 is represented by Q=q.multidot.2C/w.
[0293] Since the column 205 has a rectangular cross section, the
beltlike reinforcement 201 on the near-side surface thereof and
that on the far-side surface thereof are involved in reinforcement;
therefore, a coefficient of 2 is used. As seen from FIG. 28, length
C of arrow c 233 is represented by C=b tan .tau.. Generally, shear
force Q is partially borne by a member. However, it is assumed
that, when the deformation of the member exceeds a level
corresponding to around Q.sub.max, at which a belt becomes
significantly effective, substantially the entire shear force is
borne by belt tension.
[0294] When angle .theta. 237 is 45 degrees, width 235 of the
column 205 is b (restraint length)=30 cm. Accordingly, horizontal
forces Q.sub.max and Q.sub.min corresponding to maximum value
q.sub.max, and minimum value qmin which are previously calculated
for the polyester belt 199 (width 64 mm and thickness 4 mm) by use
of Eq. 24) to Eq. 26) are obtained as Q.sub.max=q.sub.min2b/w=18000
kgf and Q.sub.min=q.sub.min2b/w=9000 kgf. Thus, by virtue of the
effect of the reinforcement, a horizontal resistance force of not
less than 9 tf can be maintained when the width of the crack 215 is
not in excess of d.sub.max=1.2 mm.
[0295] Next will be described the results of a test conducted in
the following manner: a horizontal force was repeatedly applied to
an unreinforced column 205 and to a column 205 reinforced by use of
the polyester belt 199 (width 64 mm and thickness 4 mm), which
serves as the beltlike reinforcement 201 shown in FIG. 24, under
the conditions of FIG. 27 while displacement was controlled. Other
test conditions were as follows: the concrete strength of the
column 205 is 135 kgf/cm.sup.2; the axial ratio of reinforcement is
0.56%; the ratio of shear reinforcing bar is 0.08%; an axial force
is held constant at 37 tf (axial force ratio 0.3).
[0296] FIG. 29 is a schematic view showing the deformation of the
column 205. FIGS. 30 to 35 show experiment results, in which
horizontal displacement .delta..sub.h 239 represents the horizontal
displacement of the column 205; and vertical displacement
.delta..sub.v 241 represents the vertical displacement of the
column 205. FIG. 30 is a graph showing the relationship between
horizontal force Q of the column 205 and an envelope indicative of
displacement hysteresis of the column 205. FIG. 31 is a graph
showing the relationship among the horizontal displacement of the
column 205, the vertical displacement of the column 205, and a
horizontal force. FIG. 32 is a graph showing restoring-force
characteristics of the column 205.
[0297] In FIG. 30, the horizontal axis represents horizontal
displacement .delta..sub.h (239) of the column 205, and the
vertical axis represents horizontal force Q (shear force 227). In
FIG. 32, the horizontal axes represent horizontal displacement
.delta..sub.h (239) of the column 205 and the angle of deformation,
and the vertical axis represents horizontal force Q (shear force
227).
[0298] In FIG. 30, a reinforcement-absent curve 243a is an envelope
as observed when the column 205 is not reinforced with the beltlike
reinforcement 201, and a reinforcement-present curve 243b is an
envelope as observed when the column 205 is reinforced. The
reinforcement-present curve 243b is an envelope along the following
points on a hysteretic loop 253 shown in FIG. 32: a point
corresponding to a level 255a equivalent to the level of the Great
Hanshin Earthquake Disaster, a point corresponding to a level 255b
equivalent to two times the level of the Great Hanshin Earthquake
Disaster, a point corresponding to a level 255c equivalent to three
times the level of the Great Hanshin Earthquake Disaster, a point
corresponding to a level 255d equivalent to five times the level of
the Great Hanshin Earthquake Disaster, etc.
[0299] In FIG. 31, the horizontal axis represents horizontal
displacement .delta..sub.h (239); the upward vertical axis
represents horizontal force Q (shear force 227); and the downward
vertical axis represents vertical displacement .delta..sub.v (241).
A reinforcement-absent curve 243a and a reinforcement-present curve
243b are envelopes similar to those shown in FIG. 30. The
reinforcement-absent curve 245a shows vertical displacement 6 of
the column 205 which is not reinforced with a beltlike
reinforcement. The reinforcement-present curve 245b shows vertical
displacement .delta..sub.v of the column 205 which is reinforced
with the beltlike reinforcement 201 (polyester belt 199).
[0300] As shown in FIGS. 30 and 31, when Q.sub.max1 represents the
maximum horizontal force in the case of no reinforcement being
employed as represented by the reinforcement-absent curve 243a;
Q.sub.max2 represents the maximum horizontal force in the case of
reinforcement being employed as represented by the
reinforcement-present curve 243b; and Q.sub.min represents the
minimum horizontal force in the case of reinforcement being
employed as represented by the reinforcement-present curve 243b,
experiment data show Q.sub.max1=17.5 tf, Q.sub.max2=18 tf, and
Q.sub.min=7 tf.
[0301] In FIG. 31, the reinforcement-absent curve 243a, which shows
horizontal force Q of the unreinforced column 205, and the
reinforcement-absent curve 245a, which shows vertical displacement
.delta..sub.v drop sharply at and after the time when horizontal
force Q becomes Q.sub.max1. This supports the aforementioned
assumption that, in the case of the reinforced column 205, the
beltlike reinforcement 201 (polyester belt 199) exhibits a
reinforcement effect; i.e., the beltlike reinforcement 201 bears
substantially the entire shear force in a horizontal-displacement
region ranging from a horizontal displacement corresponding to
Q.sub.max2 to a horizontal displacement corresponding to
Q.sub.min.
[0302] The experimentally obtained value of minimum horizontal
force Q.sub.min appearing on the reinforcement-present curve 243b
is lower than a calculated value of 9 tf, which is obtained through
calculation using the models of FIGS. 27 and 28. This can be said
to be an experimental error and implies the occurrence of a drop in
strength at the bond area between the concrete surface of the
column 205 and the beltlike reinforcement 201 (polyester belt 199).
The value of maximum shear force Q.sub.max2 is substantially equal
to a calculated value of 18 tf.
[0303] As shown in FIG. 29, when horizontal displacement
.delta..sub.h of the column 205 is displacement amplitude
.delta..sub.hc 247, the reinforcement-present curve 243b indicative
of horizontal force Q has a horizontal-force inflection point 249,
and the reinforcement-present curve 245b indicative of vertical
displacement .delta..sub.v has a vertical-displacement inflection
point 251. Displacement amplitude .delta..sub.hc 247 is horizontal
displacement .delta..sub.h at around a point corresponding to the
level 255c equivalent to three times the level of the Hyogo-Ken
Nanbu Earthquake on the hysteretic loop 253 shown in FIG. 32; i.e.,
about 140 mm (angle of deformation 0.15 rad).
[0304] FIG. 33 is a graph showing the relationship between
cumulative horizontal displacement .SIGMA..epsilon..sub.h and
hysteretic absorbed energy W in the column 205. FIG. 34 is a
detailed view of FIG. 33. In FIG. 33, the horizontal axis
represents cumulative horizontal displacement
.SIGMA..epsilon..sub.h, and the vertical axis represents hysteretic
absorbed energy W.
[0305] Cumulative horizontal displacement .SIGMA..epsilon..sub.h,
which is represented by the horizontal axis in FIGS. 33 and 34, was
calculated by the equation shown below. In the equation, i is the
number of steps in data recording, and n is the current number of
steps. Cumulative horizontal displacement .SIGMA..epsilon..sub.h is
calculated as an indicator of a position on the hysteretic loop 253
shown in FIG. 51. 10 h = i = 1 n hi + 1 - hi 27 )
[0306] Cumulative absorbed energy W represented by the vertical
axis was calculated by the following equation. Cumulative absorbed
energy W is work done by horizontal force Q; i.e., by shear force
227.
W=.intg.Qd.delta..sub.h 28)
[0307] When a certain column 205 of a structure bears an axial
force 229 of P, corresponding mass m can be represented by use of
gravitational acceleration g as m=P/g. Thus, of energy which is
input to the structure and consumed until completion of vibration,
work E which is done by shear force 227 imposed on the column 205
is approximated by the following expression by use of velocity
response spectrum .delta..sub.v of earthquake motion.
E=0.5(P/g)Sv.sup.2 29)
[0308] The curve of hysteretic absorbed energy 257 shown in FIG. 33
shows hysteretic absorbed energy which is calculated from the
experimentally obtained hysteretic loop 253 shown in FIG. 51, by
use of Eq. 28). The straight lines indicative of a level 259a
equivalent to the level of the Great Hanshin Earthquake Disaster
and a level 259b equivalent to five times the level of the Great
Hanshin Earthquake Disaster represent values which are calculated
by Eq. 29) for comparison with the curve of hysteretic absorbed
energy 257. FIG. 53 additionally show values which are calculated
by Eq. 29) and represented by the straight lines indicative of a
level 259c equivalent to two times the level of the Great Hanshin
Earthquake Disaster and a level 259d equivalent to three times the
level of the Great Hanshin Earthquake Disaster. Velocity response
spectrum used in the calculation by Eq. 29) was Sv=90 cm/s at a
natural period of 0.3 sec appearing in the record of Kobe Marine
Meteorological Observatory.
[0309] FIG. 35 is a graph showing the relationship between
calculated cumulative horizontal displacement
.SIGMA..epsilon..sub.h and vertical displacement .delta..sub.v by
use of Eq. 27). In FIG. 35, the horizontal axis represents
cumulative horizontal displacement .SIGMA..delta..sub.h, and the
vertical axis represents vertical displacement .delta..sub.v (241).
As mentioned previously in the description which was given with
reference to FIG. 31, when horizontal displacement is horizontal
amplitude .delta..sub.hc 247; i.e., about 140 mm, the
vertical-displacement inflection point 251 appears. At this time,
cumulative horizontal displacement .SIGMA..delta..sub.h is about
1500 mm. As shown in FIG. 35, vertical displacement .delta..sub.v
is not greater than 5 mm (strain 0.5%) until cumulative
displacement reaches about 1500 mm at the vertical-displacement
inflection point 251.
[0310] The above-described experiment demonstrated the
following:
[0311] {circle over (1)} A reinforcement effect was exhibited for
low-strength concrete (135 kgf/cm.sup.2), which encounters
difficulty in being reinforced by a conventional method.
[0312] {circle over (2)} A reinforcement effect was exhibited
continuously over a range from small strain to large
deformation.
[0313] {circle over (3)} It was confirmed that the
reinforcement-present curve 243b shown in FIG. 49 has two
inflection points of horizontal force (a point of Q=Q.sub.max2 and
a point of Q=Q.sub.min; i.e., the horizontal-force inflection point
249).
[0314] {circle over (4)} It was confirmed that the
reinforcement-present curve 245b shown in FIG. 31 has a single
inflection point of vertical displacement .delta..sub.v (the
vertical-displacement inflection point 251). This inflection point
corresponds to the horizontal-force inflection point 249
(Q=Q.sub.min) mentioned above in {circle over (3)}. The
vertical-displacement inflection point 251 is a point at which a
mechanism represented by Eq. 21) to Eq. 26) shifts to a mechanism
in that the cross-sectional shape of the column 205 begins to be
deformed, and great axial deformation arises, since the mechanism
represented by the equations is disabled as a result of a series of
events of cumulative damage to concrete due to repeated load; a
drop in concrete strength; a drop in bonding strength .tau. between
the beltlike reinforcement 201 (polyester belt 199) and the
concrete surface of the column 205; and an increase in crack width
217 beyond limit d.sub.max.
[0315] {circle over (5)} Vertical displacement .delta..sub.v (axial
contraction of the column 205) is not greater than 0.5% until the
second inflection point of horizontal force Q; i.e., the horizontal
inflection point 249 at which Q becomes Q.sub.min, is reached;
i.e., until vertical displacement .delta..sub.v reaches
vertical-displacement inflection point 251. This range of vertical
displacement .delta..sub.v is tolerable such that a structure can
be practically reused after an earthquake.
[0316] {circle over (6)} Conceivably, in the case of reinforcement
being not carried out (as represented by the reinforcement-absent
curves 243a and 245a in FIGS. 30 and 31), before hysteretic
absorbed energy reaches the Great Hanshin Earthquake Disaster
equivalent thereof, vertical displacement .delta..sub.v increases
abruptly with a resultant collapse of the structure.
[0317] {circle over (7)} In the case of reinforcement being carried
out, vertical displacement .delta..sub.v is not greater than 0.5%
until hysteretic absorbed energy 257 shown in FIGS. 33 and 34
becomes about 2.5 times the hysteretic absorbed energy of the Great
Hanshin Earthquake Disaster. This range of vertical displacement
.delta..sub.v is tolerable such that a structure can be practically
reused after an earthquake.
[0318] {circle over (8)} In the case of reinforcement being carried
out, as shown in FIG. 35, when hysteretic absorbed energy becomes
greater than about 2.5 times that of the Great Hanshin Earthquake
Disaster (when cumulative horizontal displacement
.SIGMA..delta..sub.h becomes greater than about 1500 mm), vertical
displacement .delta..sub.v increases gradually. However, as shown
in FIGS. 50 and 32, horizontal yield strength increases, and
absorbed energy per cycle increases, whereby a vibration-damping
effect is enhanced, thereby yielding a great collapse prevention
effect.
[0319] As seen from the results of experiment shown in FIGS. 30 to
35, in which the beltlike reinforcement 201, such as the polyester
belt 199, is bonded directly to a member, such as the column 205,
exhibits continuously a reinforcement effect on deformation ranging
from a small one as observed after formation of the crack 215 to a
large one.
[0320] A conventional reinforcement method in which a member is
wrapped with reinforcement is characterized in that, in order to
prevent formation of cracks, a reinforcement material, such as
carbon fiber or wrapping iron plate, having rigidity equivalent to
or greater than that of a major dynamic component of the member is
bonded directly to the surface of the member by use of resin or the
like. The beltlike reinforcement 201, such as the polyester belt
199, is bonded directly to a member, such as the column 205 is not
adapted to suppress formation of the crack 215 on the member
surface but is adapted to restrain crack width 217 to an effective
value; for example, to about 2 mm, whereby the functional
impairment of a member is controlled to thereby maintain usability
and safety of a structure.
[0321] A method in which a high-rigidity material, such as the
polyester belt 199, is bonded directly to the surface of a member
is intended to enhance the effect of maintaining the shape of the
member with respect to deformation accompanied by finite crack 215.
As seen from Eq. 21) to Eq. 24), this effect is enhanced in
proportion to the circumferential rigidity of a reinforcement, and
the enhancement of the effect is limited by the magnitude of a
shear force to be transmitted between the surface of the member and
the reinforcement. Accordingly, through a high-rigidity
reinforcement being bonded directly to a member, a reinforcement
effect can be enhanced.
[0322] The beltlike reinforcement 201 used in the ninth embodiment
is not limited to the polyester belt 199. Any material having
strength and rigidity equivalent to those of the polyester belt 199
can be used.
[0323] The reinforcement method is such that, through control of an
increase in crack width 217, the expansion of an apparent volume of
a member is restrained. Thus, in principle, the method is identical
to that of the previous application. However, the method employs
the mechanism of restraining variation in shape and axial strain
and is verified theoretically and experimentally, thereby
indicating high practical viability thereof.
[0324] Next, a structure for enhancing a reinforcement effect for a
member involving an irregular profile and a member-to-member joint
of the present invention will be described. FIG. 36 is a
perspective view showing a state in which connecting reinforcements
269a and 269b are disposed on the joint between a column 261 and a
beam 263. The beam 263 is joined to the column 261 at right-hand
and left-hand side surfaces 265b.
[0325] The joint between the column 261 and the beam 263 is
reinforced by use of two sheetlike connecting reinforcements 269a
and four connecting reinforcements 269b. The connecting
reinforcement 269a assumes the form of a sheet and is bonded to the
column 261 and the beam 263 in such a manner as to cover the joints
between the side surfaces 265b of the column 261 and the side
surface 267a of the beam 263. A central portion of the connecting
reinforcement 269a is bonded to a side surface 265a of the column
261 and the right-hand and left-hand side surfaces 265b adjacent to
the side surface 265a. Opposite end portions of the connecting
reinforcement 269a are bonded to the side surface 267a of the beam
263.
[0326] The connecting reinforcement 269a assumes the form of a
sheet and is bonded to the column 261 and the beam 263 in such a
manner as to cover the joint between the side surface 265b of the
column 261 and the side surface 267b of the beam 263. The
connecting reinforcements 269a and 269b are, for example,
stretchable, fibrous or rubber sheet materials.
[0327] The connecting reinforcements 269a and 269b are not
necessarily sheetlike reinforcements but may assume the form of a
beltlike reinforcement, such as the polyester belt 199. The
thickness, width, length, etc. of the connecting reinforcements
269a and 269b, either sheetlike or beltlike, are determined to
provide a required amount of reinforcement.
[0328] The connecting reinforcements 269a and 269b may be bonded to
the column 261 and the beam 263 in a tentative condition but may be
bonded in such a manner as to yield strength. Generally, the
displacement amplitude of a structure depends greatly on the
deformation of a member-to-member joint. Thus, in view of the
amount of reinforcement being determined by the method shown in
step 309 of FIG. 40, which will be described later, use of the
latter bonding is practical.
[0329] FIG. 37 is a perspective view showing a state in which a
beltlike reinforcements 271a and 271b are disposed on the joint
between the column 261 and the beam 263. In FIG. 37, a single
beltlike reinforcement 271a and two beltlike reinforcements 271b
are disposed in such a manner as to cover the connecting
reinforcements 269a and 269b which are disposed as shown in FIG.
36. The beltlike reinforcement 271a is disposed on the exterior of
a bigger member; i.e., on the exterior of the column 261. The
beltlike reinforcement 271a is wound onto the column 261 in such a
manner as to be continuously wound between a portion of the column
261 located above the joint between the column 261 and the beam 263
and a portion of the column 261 located below the joint while
obliquely crossing the joint. The beltlike reinforcement 271b is
disposed on the exterior of a thinner member; i.e., on the exterior
of the beam 263. The beltlike reinforcement 271b is independently
wound about the right-hand and left-hand beams 263 joined to the
column 261.
[0330] The above-described method is repeatedly carried out until a
required amount of reinforcement is obtained. In FIG. 37, the
beltlike reinforcements 271a and 271b are disposed in two layers
and cross-wound onto the joint between the column 261 and the beam
263.
[0331] The beltlike reinforcements 271a and 271b are bonded to the
column 261 and the beam 263 in such a manner as to yield strength.
FIG. 38 is a sectional view of the joint between the column 261 and
the beam 263 on which the connecting reinforcements 269b, etc. are
disposed. The beltlike reinforcements 271a and 271b are disposed on
the connecting reinforcement 269b in a winding condition. The
column 261 or the beam 263 and the sheetlike connecting
reinforcement 269b are bonded such that tension is mutually
transmitted via shear resistance of a bond zone. Similarly are
bonded the following combinations: the connecting reinforcement
269b and the beltlike reinforcements 271a and 271b; the column 261
or the beam 263 and the connecting reinforcement 269a; and the
connecting reinforcement 269a and the beltlike reinforcements 271a
and 271b.
[0332] In case of need, a reinforcement 273a is wound about the
exterior of the column 261, and a reinforcement 273b is wound about
the exterior of the beam 263. The reinforcements 273a and 273b are
stretchable sheetlike or beltlike materials.
[0333] As described above, according to the reinforced structure,
the connecting reinforcements 269a and 269b are disposed on the
joint between the column 261 and the beam 263 so as to enhance a
member-to-member reinforcement effect. Furthermore, the beltlike
reinforcement 271a is cross-wound onto a joint of a bigger member;
i.e., about a joint of the column 261, and the beltlike
reinforcements 271a and 271b are wound about the exterior of the
column 261 and that of the beam 263 in layers, to thereby obtain a
required amount of reinforcement.
[0334] In FIGS. 36 and 37, the reinforcement is cross-wound onto
the joint. However, the reinforcement can be wound about the joint
in the form of the letter T or the like. Reinforcement is
applicable not only to the joint between a column and a beam but
also to the joint between other members. The method can be combined
with the method using slits or bores. This combined method is
particularly effective for reinforcing the joint between members of
greatly different thicknesses or shapes, such as the joint between
a slab and a beam or the joint between a wall and a beam.
[0335] When a sufficient amount of reinforcement can be obtained
merely by use of the beltlike reinforcements 271a and 271b, the
connecting reinforcements 269a and 269b can be omitted.
[0336] In the above reinforced structure of a structural body, the
reinforcing member is made of a material having high ductility and
high bendability, or extensibility, and installed on the surface of
or inside a structure member or substrate through the fixation
using an adhesive, so as to constrain the apparent volume expansion
of the structure member to control the change in shape or the
damage of the structure member.
[0337] A material which is inexpensive and facilitates working and
bonding, such as a polyester sheet, is used as a reinforcement
material. The Young's modulus of such a material is about one-tenth
that of concrete or one-hundredth that of iron. Thus, the
reinforcement material's effect of bearing part of a load imposed
on a member during the elastic stage accompanied by very small
strain as do reinforcing bars of reinforced concrete, is very weak;
specifically, as weak as the above-mentioned Young's modulus
ratios.
[0338] However, when repeated imposition of load induces yielding
and cracking of main component materials, such as concrete and
iron, of a column; i.e., when plastic deformation begins, the
rigidity of the member drops; thus, the method of the previous
application exhibits significant effectiveness. Even after concrete
or a like component material of the column assumes a granular form
and then a powder form, and iron undergoes significant plastic
deformation or ruptures retains these component materials in a
unitary shape, thereby exhibiting the capability of maintaining an
axial force and the capability of resisting an external force, such
as bending and shearing.
[0339] The reinforced member absorbs very large energy in the
above-mentioned sequential repeated-deformation process while
maintaining rigidity, thereby preventing the collapse of a
structure which would otherwise result from reception of an abrupt
external force, such as a seismic force.
[0340] FIG. 41 is a diagram showing the relationship between
cumulative deformation and hysteretic absorbed energy with respect
to a reinforced member on which a repeated load is imposed. The
horizontal axis represents cumulative deformation, and the vertical
axis represents hysteretic absorbed energy. As a result of a
repeated external force being imposed on a member during the member
being deformed with involvement of finite cracking, component
materials of the member are partially ruptured. A shear force
transmitted between the member and a reinforcement decreases
accordingly. As a result, a reinforcement effect weakens, and the
effect of retaining the shape of the member also weakens. The
rupture of component materials of the member induced as a result of
reception of a repeated load can be measured in terms of work done
by the external force; i.e., in terms of hysteretic absorbed
energy.
[0341] A certain limit (called a shape retainment limit energy 275)
is present according to the type and amount of material. When this
limit is exceeded, a material behaves in a granular fashion, and
thus the shape of a member begins to vary significantly. A member
reinforced according to a method of the present invention or the
previous application is deformed such that the cross section
assumes a circular shape, and the entire shape approaches to the
shape of linked balls. Accordingly, the shape of a structure also
varies significantly.
[0342] The method of the present application is characterized by
being able to cope with a wide energy region and a wide deformation
region, and an enhancement of an effect to be yielded as shown in
FIG. 41. When the method of the present invention are applied to a
seismic isolator, the seismic isolator can absorb energy in such an
amount that a material having a volume equivalent to that of the
seismic isolator is pulverized substantially completely, while
variation in shape is minimized, and rigidity is retained. This is
a very efficient behavior for a seismic isolator. When a special
filler is mixed into a component material of a seismic isolator,
the filler functions to internally reinforce the material through
utilization of energy, such as heat, to be generated by work which
is done by an external force in the above-mentioned process,
thereby further enhancing a seismic isolation effect.
[0343] Next, the fibrous sheetlike reinforcements and beltlike
reinforcements as mentioned above are impregnated with resin will
be described. FIG. 42 is a graph showing the relationship between
tensile stress and strain with respect to a reinforcement material
impregnated with resin and a reinforcement material unimpregnated
with resin. The vertical axis represents tension, and the
horizontal axis represents extensional strain (%).
[0344] An impregnated-with-resin curve 277 shows the stress-strain
relation obtained from a tensile test which was conducted on a
polyester sheetlike textile impregnated with epoxy resin after the
resin was cured. An unimpregnated-with-resin curve 279 shows the
stress-strain relation obtained from a tensile test which was
conducted on the same sheetlike textile unimpregnated with epoxy
resin.
[0345] Comparison in FIG. 42 between the impregnated-with-resin
curve 277 and the unimpregnated-with-resin curve 279 shows the
following: as a result of impregnation with resin, rigidity; i.e.,
the gradient of the parting line of the graph, is significantly
large at a strain of 0% to about 3%; and deformation can be
maintained without rupture until large strain is reached. Similar
test results are also obtained from a polyester beltlike material,
such as the polyester belt 199 shown in FIG. 21.
[0346] The test results shown in FIG. 42 show the following: as a
result of a sheet or beltlike material woven from polyester fiber
being impregnated with resin, resin yields the effect of
restraining deformation of fiber for the range of small strain;
thus, the material represented by the impregnated-with-resin curve
277 exhibits increased rigidity as compared with the material
represented by the unimpregnated-with-resin curve 279. When
deformation increases, the material represented by the
impregnated-with-resin curve 277 loses the above-mentioned effect
without significant breakage of fiber. As a result, deformation can
be maintained until a large strain of not less than 15% is
reached.
[0347] Thus, through a reinforcement material impregnated with
resin; i.e., a material of a single kind, enhances the effect of
restraining deformation for the range of small strain as well as
yields the effect of bearing a load for the range of large
strain.
[0348] The aforementioned reinforcing member can be designed as
follows.
[0349] As described above, the dynamic property (the relationship
between external force and deformation) of the reinforced structure
is defined by the following parameters. Thus, the reinforced
structure can be designed by calculating the performance of a
structural body subject to reinforcement, according to these
parameters and data of the structural body.
[0350] 1) Thickness of reinforcing member t
[0351] 2) Young's modulus of reinforcing member E.sub.f
[0352] 3) Fracture strain of reinforcing member
.epsilon..sub.fb
[0353] 4) Reinforcing-member stress at yield of fixation structure
.tau..sub.fmax
[0354] 5) Reinforcing-member installation mode (Whether
reinforcing-member is closingly looped (FIG. 1) or not (FIG.
3))
[0355] 6) Reinforcing-member installation range (When not closingly
looped) expressed by b
[0356] 7) Peeling-limit elongation .delta.1
[0357] For determination of reinforcing-member stress at yield of
fixation structure, the following 8) or 9) can be used.
[0358] 8) Constraint length b and Average fixation strength
.tau..sub.f
[0359] 9) Peeling energy of boundary surface of fixation structure
G.sub.f
[0360] Further, the gap width and reinforcing-member tensile force
in a SRF-reinforced structure has a relationship as shown in FIG.
44. Specifically, if the gap width is increased from zero, a
reinforcing member will be elongated in a fixation zone, and
thereby a reinforcing-member stress will be generate. When the
elongation of the reinforcing member on the gap reaches .delta.1,
the release of the fixation structure is initiated to generate a
free length a (FIG. 44). If the fixation is based on bonding, and
the reinforcing member is bonded even at a position sufficiently
away from the gap, the fixation force will be kept at an
approximately constant value as long as a constraint length (the
distance between the gap and a position where the fixation force is
not zero) can be increased in conjunction with the increase of the
gap width (FIG. 4). This is the range from Point A to Point B in
FIG. 44. Subsequently, a fixation length (s=b-a) is reduced, and
thus the reinforcing-member stress is reduced. This is the range
from Point B to Point C. According to the theory shown in the
expressions [1] to [4], the bonding is released all at once when
the reinforcing-member stress becomes half of its maximum value. If
the reinforcing member is closingly looped, or a geometrical
constraint exists at the corner of the structure member or the
like, the fixation force will be maintained to increase a
reinforcing-member tensile force in proportion to the gap width
until the reinforcing member reaches a fracture stress (stress
corresponding to the fracture strain .epsilon..sub.fb) (range from
Point C to Point D).
[0361] For example, in case of a bar-shaped structure member, the
relationship between reinforcing-member tensile force and restoring
force can be determined from the theory as shown in the expressions
[9] and [10], or an experimental test. Further, the
reinforcing-member elongation .delta..sub.1 providing the maximum
value of the reinforcing-member tensile force is a value derived
from integrating strains in the fixation zone of the reinforcing
member at the time of the limit where the bonding is released (when
the reinforcing-member tensile force reaches .tau..sub.fmax), and
becomes smaller as the Young's modulus of the reinforcing member is
increased. This factor is ignored in the theory shown in the
expressions [1] to [4].
[0362] The maximum reinforcing-member tensile force may be derived
from dividing the product of the restraint length and the average
bonding strength by the reinforcing-member thickness from the
expression [4]. However, if the reinforcing member is wounded
around a structure member, and the structure member is installed
over a wide range, the constraint length cannot be figured out in
some cases. This problem can be solved by determining the maximum
reinforcing-member tensile force using the boundary-surface peeling
energy in the following expression [101]: 11 f max = 2 E f G f t [
101 ]
[0363] The boundary-surface peeling energy is defined as energy
required for peeling the bonding boundary-surface of unit area
between a thin elastic body and a substrate as shown in FIG. 44,
and can be calculated from the following expression [102] using the
maximum tensile force .sigma..sub.fmax caused in the elastic body
and the thickness t and Young's modulus of the elastic body, which
are obtained as the reinforcing bar. Further, while a maximum
reinforcing-member tensile force .sigma..sub.fmax is calculated
using the expression [101], it is given that the reinforcing-member
stress does not go beyond a value corresponding a
reinforcing-member strain of 1%.
[0364] The above apparent yield stress (.sigma..sub.fmax in the
expressions [101] and [102]) is a maximum stress capable of being
borne before the fixation of the reinforcing member is released
(FIG. 45), and calculated from the Young's modulus of the
reinforcing member, the boundary-surface peeling energy and the
thickness of the reinforcing member using the expression [101]. In
the expression [101], the apparent yield stress is reduced in
reverse proportion to the square root of the thickness. Thus, the
reinforcing-member thickness can be determined by a simple repeated
calculation.
[0365] As above, while the present invention has been described in
conjunction with preferred embodiments of a reinforced structure,
reinforcing method, quake-absorbing structure, and reinforcing
member for a structural body according to the present invention,
the present invention is not limited to such embodiments. It is
obvious to those skilled in the art that various changes and
modifications may be made therein without departing from the spirit
and scope of the present invention. Therefore, it is intended that
such changes and modifications are obviously encompassed within the
scope of the present invention.
Industrial Applicability
[0366] As mentioned above, the present invention can provide a
reinforcing material or member excellent in ductility and
load-withstanding capacity, quickly at a low cost. result of a
peeling test. 12 G f = t 2 E f f max 2 [ 102 ]
[0367] The expression [101] is obtained by resolving the formula
[102] about .sigma..sub.fmax.
[0368] In a design for SRF-reinforcing a reinforced concrete
structure member, a conventional design formula for reinforced
concrete structure members can be applied to the calculation of the
reinforcement effect of a SRF reinforcing member by substituting
the SRF reinforcing member with a reinforcing bar and calculating
the reinforcement effect using the boundary-surface peeling energy
etc. by use of the phenomenon that a SRF reinforcing member
apparently yields at .sigma..sub.fmax as shown in FIG. 55
(expression [103]). However, there is possibility that the gap
width in the design limit state does not reach the peeling-limit
elongation .delta.1 illustrated in FIGS. 44 and 55 due to a small
Young's modulus of the SRF reinforcing member as compared to that
of reinforcing bar. Thus, it is required to take notice of checking
whether .delta..sub.1 is caused within the design limit, through an
experimental test or the like, or putting a limit on the
reinforcing-member stress.
[0369] For example, in a design for a SRF reinforcing member
installed based on bonding in such a manner that it is wounded
around a bar-shaped reinforced concrete structure member shown in
FIG. 7, an equivalent shear reinforcing bar amount P.sub.wf after
reinforcement is calculated as follows: 13 P wf = P w + 2 t b m f
max sy [ 103 ]
[0370] wherein t is the thickness of the reinforcing member, bm
being the width of the section of the structure member, pw being
the ratio of the shear reinforcing bar to the structure member
subject to reinforcement, and .sigma..sub.sy being a yield stress
of the The effects of the reinforcing member according to the
present invention is effective to repair, maintenance and
reinforcement of existing structure bodies, and usable in new
structural bodies. In either case, the cost, construction period
etc. required for satisfying a desired performance can be reduced
as compared to those in conventional techniques. The reinforcing
material or member according to the present invention is useable as
a safeguard against sudden external forces such as explosion, which
have been untreatable by conventional techniques. In addition, the
reinforcing member installed on the outer surface of a structure
member as a primary element thereof makes it possible to provide a
reinforced structure readily at a low cost and achieve enhanced
reinforcement performance. Furthermore, the present invention
facilitates reuse of decrepit or affected structural bodies to
promote effective use of existing structural bodies and industrial
resources and to allow industrial wastes to be reduced.
[0371] Moreover, a reinforcement configuration, a seismic isolator,
and a reinforcement method for a structure according to the present
invention can suitably be applied to, for example, the following
cases: a member to be reinforced involves undulation or an
irregular profile; a member is joined to or located in proximity to
another member or a nonstructural member; a reinforcement is
possibly deteriorated due to interaction between a member and the
reinforcement or between the reinforcement and an external
environment; a reinforcement effect must encompass a small
deformation through a large deformation; and seismically isolating
reinforcement is required.
* * * * *