U.S. patent application number 16/549310 was filed with the patent office on 2019-12-12 for steel form.
This patent application is currently assigned to TAKENAKA CORPORATION. The applicant listed for this patent is JFE METAL PRODUCTS CORPORATION, JFE STEEL CORPORATION, TAKENAKA CORPORATION. Invention is credited to Naohiro FUJITA, Takayuki HIRAYAMA, Tomohiro KINOSHITA, Takahiro MACHINAGA, Yukio MURAKAMI, Kazuto NAKAHIRA, Hirokazu NOZAWA, Yuuichirou OKUNO, Takanori SHIMIZU, Hiroto TAKATSU, Seishi WATANABE, Kenji YAMAZAKI, Hiroori YASUOKA.
Application Number | 20190376283 16/549310 |
Document ID | / |
Family ID | 63370141 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190376283 |
Kind Code |
A1 |
HIRAYAMA; Takayuki ; et
al. |
December 12, 2019 |
STEEL FORM
Abstract
A steel form is a steel form for forming a binding beam,
including: a pair of Z-steels, wherein each of the pair of Z-steels
is provided with a bottom plate portion and a side plate portion
extending upward from the bottom plate portion, the bottom plate
portion has a joining surface for joining the respective bottom
plate portions of the pair of Z-steels to each other, and a groove
portion allowing concrete placement is formed by the bottom plate
portion and the side plate portion of each of the pair of
Z-steels
Inventors: |
HIRAYAMA; Takayuki; (Osaka,
JP) ; NAKAHIRA; Kazuto; (Osaka, JP) ; NOZAWA;
Hirokazu; (Hyogo, JP) ; OKUNO; Yuuichirou;
(Nara, JP) ; MACHINAGA; Takahiro; (Fukuoka,
JP) ; FUJITA; Naohiro; (Nara, JP) ; TAKATSU;
Hiroto; (Chiba, JP) ; YAMAZAKI; Kenji; (Tokyo,
JP) ; MURAKAMI; Yukio; (Chiba, JP) ;
KINOSHITA; Tomohiro; (Kanagawa, JP) ; SHIMIZU;
Takanori; (Chiba, JP) ; WATANABE; Seishi;
(Tokyo, JP) ; YASUOKA; Hiroori; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAKENAKA CORPORATION
JFE STEEL CORPORATION
JFE METAL PRODUCTS CORPORATION |
Osaka
Tokyo
Tokyo |
|
JP
JP
JP |
|
|
Assignee: |
TAKENAKA CORPORATION
Osaka
JP
JFE STEEL CORPORATION
Tokyo
JP
JFE METAL PRODUCTS CORPORATION
Tokyo
JP
|
Family ID: |
63370141 |
Appl. No.: |
16/549310 |
Filed: |
August 23, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2018/005971 |
Feb 20, 2018 |
|
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16549310 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04B 5/10 20130101; E04C
3/293 20130101; E04B 5/40 20130101; E04B 1/16 20130101; E04B 1/167
20130101; E04B 5/04 20130101 |
International
Class: |
E04B 5/04 20060101
E04B005/04; E04B 1/16 20060101 E04B001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2017 |
JP |
2017-036750 |
Claims
1. A steel form for steel-framed concrete beam formation,
comprising: a pair of frame members, wherein each of the pair of
frame members is provided with a bottom plate portion and a side
plate portion extending upward from the bottom plate portion, the
bottom plate portion has a joining surface for joining the
respective bottom plate portions of the pair of frame members to
each other, and a groove portion allowing concrete placement is
formed by the respective bottom and side plate portions of the pair
of frame members.
2. The steel form according to claim 1, wherein an allowable
bending moment or an allowable shear force of the steel-framed
concrete beam is calculated by Equation (1) below:
F.sub.a=F.sub.RC+.beta.F.sub.S (Equation 1) wherein, F.sub.a: an
allowable bending moment or an allowable shear force of the
steel-framed concrete beam, F.sub.RC: an allowable bending moment
or an allowable shear force of the concrete, .beta.: a burden
factor of an allowable bending moment or an allowable shear force
of the steel form, which is 0.5 or less, and F.sub.S: an allowable
bending moment or an allowable shear force of the steel form.
3. The steel form according to claim 1, wherein a part of the
steel-framed concrete beam is joined to a girder, and the steel
form is provided with an end portion on the girder side in a
longitudinal direction of the steel form, accommodated in the
girder via, a notch formed in a side surface of the girder, and
having a length equal to or greater than a cover thickness of the
girder.
4. The steel form according to claim 1, wherein a non-opening
member for fixing the pair of side plate portions to each other is
provided in a range from an upper end position of the pair of side
plate portions to a position below the upper end position by
one-third of a height of the pair of side plate portions.
5. The steel form according to claim 1, wherein the steel form is
provided with a flange portion extending outward from an upper end
of the side plate portion.
6. The steel form according to claim 5, wherein the steel form is
provided with a reinforcing portion extending downward or upward
from an outer end of the flange portion.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of Patent
Application in Japan No. 2017-036750 filed on Feb. 28, 2017 and the
benefit of PCT application No. PCT/JP2018/005971 filed on Feb. 20,
2018, the disclosure of which is incorporated by reference its
entirety.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are herein incorporated by reference in their
entirety to the same extent as if each individual publication or
patent application was specifically and individually indicated to
be incorporated by reference.
TECHNICAL FIELD
[0003] The present invention relates to a steel form.
BACKGROUND ART
[0004] Proposed in the related art is a method for using a grooved
steel form (approximately U-shaped in cross section) matching the
outer shell shape of a beam as a beam form for labor-saving form
construction for example, Patent Document 1).
CITATION LIST
Patent Document
[0005] Patent Document 1: Japanese Unexamined Patent Application
Publication No. Heisei 10-140654
SUMMARY OF THE INVENTION
Technical Problem
[0006] The steel form described in Patent Document 1 needs to be
formed by processing a thin steel plate into a shape matching the
outer shell shape of a beam by, for example, roll molding or press
molding. As a result, it takes labor and cost to process the steel
form. Besides, the grooved steel form is bulky in terms of
transport, and thus the number of the grooved steel forms that can
be transported at one time is limited. As a result, it takes labor
and cost to transport the steel form.
[0007] It is an object of the present invention to solve the
problems of the above mentioned prior arts.
Means for Solving the Problems
[0008] One aspect of the present invention provides a steel form,
which is a steel form for steel-framed concrete beam formation,
includes a pair of frame members, wherein each of the pair of frame
members is provided with a bottom plate portion and a side plate
portion extending upward from the bottom plate portion, the bottom
plate portion has a joining surface for joining the respective
bottom plate portions of the pair of frame members to each other,
and a groove portion allowing concrete placement is formed by the
respective bottom and side plate portions of the pair of frame
members.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1(a) and 1(b) are a set of views illustrating a
steel-framed concrete beam (binding beam) according to Embodiment 1
of the invention, in which FIG. 1(a) is a left side view and FIG.
1(b) is a cross-sectional view taken along arrow A-A in FIG.
1(a).
[0010] FIG. 2 is an exploded perspective view illustrating a
temporary state during construction in the vicinity of the joining
portion between the binding beam and a girder.
[0011] FIG. 3 is a view illustrating the relationship between a
cross section of the binding beam and calculation parameters.
[0012] FIG. 4 is a graph showing the relationship between a slab
thickness and a long-term bending rigidity ratio.
[0013] FIG. 5 is a graph showing the relationship between the slab
thickness and a short-term bending rigidity ratio.
[0014] FIG. 6 is a graph showing the relationship between the load
that is applied to the binding beam and the shear rigidity ratio of
a steel form, which pertains to a case where no web opening is
present.
[0015] FIG. 7 is a graph showing the relationship between the load
that is applied to the binding beam and the shear rigidity ratio of
the steel form, which pertains to a case where a web opening is
present.
[0016] FIGS. 8(a)-8(c) are a set of cross-sectional perspective
views corresponding to the A-A arrow cross section in FIG. 1(a), in
which FIG. 8(a) illustrates the binding beam at the completion of a
steel form installation step, FIG. 8(b) illustrates the binding
beam at the completion of main bar arrangement, deck plate
installation, and placement steps, and FIG. 8(c) illustrates the
binding beam at the completion of a penetration step.
[0017] FIGS. 9(a)-9(c) are a set of cross-sectional perspective
views corresponding to the A-A arrow cross section in FIG. 1(a), in
which FIG. 9(a) illustrates the binding beam at the completion of
steel form installation and cylindrical form installation steps,
FIG. 9(b) illustrates the binding beam at the completion of main
bar arrangement, deck plate installation, and placement steps, and
FIG. 9(c) illustrates the binding beam at the completion of a
penetration step.
[0018] FIGS. 10(a) and 10(b) are a set of views illustrating a
state where a Z-steel is transported, in which FIG. 10(a) is an end
view illustrating the state of transport of a Z-steel of Embodiment
1 and FIG. 10(b) is an end view illustrating the state of transport
of a Z-steel according to a first modification example.
[0019] FIGS. 11(a) and 11(b) are a set of views illustrating a
steel form according to a second modification example, in which
FIG. 11(a) is a plan view of the steel form that is yet to be bent
and FIG. 11(b) is a side view of the steel form that is bent.
[0020] FIGS. 12(a) and 12(b) are a set of views illustrating the
vicinity of the joining portion between a binding beam and a girder
according to a third modification example, in which FIG. 12(a) is a
left side view and FIG. 12(b) is a cross-sectional view taken along
arrow B-B in FIG. 12(a).
[0021] FIGS. 13(a) and 13(b) are a set of views illustrating the
vicinity of the joining on between a binding beam and a girder
according to a fourth modification example, in which FIG. 13(a) is
a right side view and FIG. 13(b) is a plan view.
[0022] FIG. 14 is a right side view illustrating the vicinity of
the joining portion between a binding beam and a girder according
to a fifth modification example.
[0023] FIG. 15 is a right side view illustrating the vicinity of
the joining portion between a binding beam and a girder according
to a sixth modification example.
[0024] FIG. 16 is a perspective view of an end portion of the steel
form of the binding beam in FIG. 15.
[0025] FIG. 17 is a right side view illustrating the vicinity of
the joining portion between a binding beam and a girder according
to a seventh modification example.
[0026] FIG. 18 is a side view illustrating the vicinity of the
joining portion between a binding beam and a girder according to an
eighth modification example.
[0027] FIG. 19 is a plan view of FIG. 18.
[0028] FIG. 20 is a cross-sectional view corresponding to the A-A
arrow cross section in FIG. 1(a) and is a cross-sectional view of a
steel form of a binding beam according to a ninth modification
example.
[0029] FIG. 21 is a cross-sectional view corresponding to the A-A
arrow cross section in FIG. 1(a) and is a cross-sectional view of a
steel form of a binding beam according a tenth modification
example.
[0030] FIGS. 22(a) and 22(b) are a set of cross-sectional views
corresponding to the A-A arrow cross section in FIG. 1(a), in which
FIG. 22(a) illustrates a steel form of a binding beam according to
an eleventh modification example and FIG. 22(b) illustrates a steel
form of a binding beam according to a twelfth modification
example.
[0031] FIGS. 23(a) and 23(b) are a set of cross-sectional views
corresponding to the A-A arrow cross section in FIG. 1(a), in which
FIG. 23(a) illustrates a steel form of a binding beam according to
a thirteenth modification example and FIG. 3(b) illustrates a steel
form of a binding beam according to a fourteenth modification
example.
DESCRIPTION OF EMBODIMENTS
[0032] Embodiments of a steel form according to the invention will
be described in detail below with reference to accompanying
drawings. The basic concepts of the embodiments ([I]) will be
described first, and then details of the embodiments ([II]) will be
described. Modification examples regarding the embodiments ([III])
will be described last. The invention is not limited by the
embodiments.
[I] Basic Concepts of Embodiments
[0033] The basic concepts of the embodiments will be described
first.
[0034] The embodiments relate to a steel form. The "steel form" is
a form provided with steel for forming steel-framed concrete beams
constituting building. The "steel-framed concrete beam" is a beam
provided with at least a steel frame and concrete. The steel-framed
concrete beam may be provided with a component other than the steel
frame and the concrete. For example, the embodiments illustrate an
example in which the steel-framed concrete beam is configured as a
steel-framed reinforced concrete beam that has a rebar in addition
to a steel frame and concrete. Although the steel-framed reinforced
concrete beam may be provided with, for example, a main bar and a
stirrup as the rebar, a case where the steel-framed reinforced
concrete beam is provided with a main bar and no stirrup will be
described below. The steel-framed concrete beam may be provided
with, for example, a stirrup and no main bar, both a main bar and a
stirrup, or no main bar and no stirrup.
[0035] The steel frame is capable of having any shape insofar as
the steel frame functions as a form allowing concrete placement. A
case where the steel frame has an axial cross section in a hat
shape (a shape obtained by joining a pair of Z-steels to each
other) will be described below.
[0036] The steel-framed concrete beam according to the embodiments
is applicable to any installation floor. Although a case where the
steel-framed concrete beam is a second floor beam will be described
below, the steel-framed concrete beam is applicable to beams of
other floors as well. Although a case where the steel-framed
concrete beam is a binding beam will be described below, the
steel-framed concrete beam may be a girder as well.
[II] Details of Embodiments
[0037] Details of the embodiments will be described below
Embodiment 1
[0038] The steel-framed concrete beam according to Embodiment 1
will be described first.
Configuration
[0039] FIG. 1 is a set of views illustrating the steel-framed
concrete beam according to Embodiment 1 (hereinafter, simply
referred to as "binding beam" 1). FIG. 1(a) is a left side view and
FIG. 1(b) is a cross-sectional view taken along arrow A-A in FIG.
1(a). As illustrated in FIG. 1, the binding beam 1 according to
Embodiment 1 is provided with a steel form 10, binding beam
concrete 20, main bars 30, and web openings (through holes) 40. In
the following description, the +X-X direction in each drawing will
be referred to as "width direction" as necessary. In particular,
the +X direction will be referred to as "rightward direction" and
the -X direction will be referred to as "leftward direction". The
+Y-Y direction will be referred to as "depth direction" or
"forward-rearward direction". In particular, the +Y direction will
be referred to as "forward direction" and the -Y direction will be
referred to as "rearward direction". The +Z-Z direction will be
referred to as "height direction" or "upward-downward direction".
In particular, the +Z direction will be referred to as "upward
direction" and the -Z direction will be referred to as "downward
direction". As for a vertical plane (YZ plane) passing through the
axial center of the steel-framed concrete beam, the direction
toward the plane along the width direction (+X-X) will be referred
to as "inward direction" and the direction away from the plane
along the width direction (+X-X) will be referred to as "outward
direction".
Configuration-Steel Form
[0040] The steel form 10 is a steel form that has a groove portion
(described later) for placing the binding beam concrete 20. This
steel form 10 is provided in each binding beam 1 constituting a
building and is disposed so as to cover the binding beam 1 from
below. As illustrated in the drawing, the steel form 10 of
Embodiment 1 is formed by a pair of (that is, two) Z-steels 11
being mutually joined in bottom plate portions 12 (described later)
at a construction site. The invention is not limited thereto, and
the steel form 10 may be integrally formed with a single member or
may be formed by three or more members being combined. In a case
where three or more members are combined as described above, for
example, the integrally formed members (the bottom plate portion
12, a side plate portion 13, a flange portion 14, and a reinforcing
portion 15 to be described later) that constitute the Z-steel 11
may be formed separately. Each of the pair of Z-steels 11 can be
substantially similar in configuration to the other, and thus only
one of the Z-steels 11 will be described below. In a case where the
Z-steels 11 need to be distinguished from each other, the Z-steel
11 that is positioned on the right of the binding beam 1 (in the +X
direction) will be referred to as "right Z-steel" and the Z-steel
11 that is positioned on the left of the binding beam 1 (in the -X
direction) will be referred to as "left Z-steel". A specific method
for forming the steel form 10 will be described later.
[0041] The Z-steel 11 is a frame member that constitutes the steel
form 10. As illustrated in FIG. 1(b), the Z-steel 11 is a steel
material that has a substantially Z-shaped axial cross section. The
Z-steel 11 is provided with the bottom plate portion 12, the side
plate portion 13, the flange portion 14, and the reinforcing
portion 15.
[0042] The bottom plate portion 12 is a steel plate positioned on
the bottom surface of the steel form 10. The bottom plate portion
12 has a joining surface 16 for mutually joining the respective
bottom plate portions 12 of the pair of Z-steels 11. The pair of
Z-steels 11 are joined to each other on the joining surface 16. For
example, in Embodiment 1, a part of the bottom plate portion 12 of
the right Z-steel is superposed on a part of the bottom plate
portion 12 of the left Z-steel and each of the parts where the pair
of Z-steels 11 are in contact with each other (the upper surface of
the bottom plate portion 12 of the left Z-steel and the lower
surface of the bottom plate portion 12 of the right Z-steel) is the
joining surface 16. The joining on the joining surface 16 can be
performed by any specific method. For example, in Embodiment 1, a
plurality of bolt holes (not illustrated) are spaced apart along
the longitudinal direction (+Y-Y direction) of the beam in the
joining surfaces 16 of both Z-steels 11 and both Z-steels 11 are
joined by bolt fastening by means of the bolt holes. Specific
joining methods are not limited thereto. For example, welding-based
joining and screw penetration-based joining may be performed
instead.
[0043] The side plate portion 13 is a steel plate extending in the
upward direction from the bottom plate portion 12. Specifically,
the side plate portion 13 is a part that is folded back from the
outer end of the bottom plate portion 12 and extends to the upper
end of the beam and is positioned so as to cover the left and right
sides of the binding beam 1. The length of the side plate portion
13 in the height direction (+Z-Z direction) is longer, by the
thickness of the bottom plate portion 12, in the left Z-steel than
in the right Z-steel. This is for the upper end positions of the
side plate portions 13 of both Z-steels 11 (that is, the height
positions of the flange portions 14) to coincide with each other
when the pair of Z-steels 11 are overlapped.
[0044] In the following description, the part that is formed by the
side plate portions 13 and the bottom plate portions 12 of a pair
of the steel forms 10 and has a U-shaped axial cross section will
be referred to as groove portion as necessary. Concrete can be
placed in the groove portion by the steel form 10 forming the
groove portion as described above. The lower and side parts of the
binding beam 1 are covered with a steel plate by the groove
portion, and thus it is possible to deter steam from escaping from
the lower and side parts of the binding beam concrete 20 during a
fire, it is possible to deter a temperature rise in the room below
the binding beam 1, and it is possible to improve the fire
resistance performance of the binding beam 1.
[0045] The flange portion 14 is a steel plate extending in the
outward direction from the upper end of the side plate portion 13.
Specifically, the flange portion 14 is a part that is folded back
in the outward direction from the upper end of the side plate
portion 13 and extends along a horizontal plane, and a deck plate 3
is placed and screwed on the flange portion 14. Although a case
where this deck plate 3 is a known corrugated steel plate will be
described, the invention is not limited thereto and a flat plate
may be used as the deck plate 3. Although illustration is omitted,
the binding beams 1 are arranged side by side at intervals along
the longitudinal direction of a girder 2, one end portion of the
deck plate 3 is placed in the flange portion 14 of one binding beam
1 as illustrated in FIG. 1(b), and the other end portion of the
deck plate 3 is similarly placed in the flange portion 14 of the
binding beam 1 that is adjacent to the one binding beam 1. By the
flange portion 14 being provided as described above, the load of
slab concrete 4 (described later) can be received by the flange
portion 14 and is allowed to smoothly flow to the binding beam 1
and the proof stress of the binding beam 1 is improved.
[0046] The reinforcing portion 15 is a steel plate extending in the
downward direction from the outer end of the flange portion 14. By
the reinforcing portion 15 being provided as described above and
thickness being given to the outer end of the flange portion 14,
the local buckling of the outer end of the flange portion 14 that
pertains to a case where the slab concrete 4 is placed and the
flange portion 14 receives the load of the slab can be deterred. In
addition, it is possible to reduce the overall thickness of the
steel form 10 by locally reinforcing only a low-strength part by
means of the reinforcing portion 15. The reinforcing portion 15 of
Embodiment 1 extends in the downward direction from the outer end
of the flange portion 14. The invention is not limited thereto and
the reinforcing portion 15 may extend in, for example, the upward
direction.
Configuration-Binding Beam Concrete
[0047] The binding beam concrete 20 is concrete placed in the
groove portion that the pair of side plate portions 13 and the
bottom plate portion 12 of the steel form 10 constitute. The
binding beam concrete 20 is known concrete solidified after filling
in the groove portion, and the plurality of web openings 40 are
formed in the binding beam concrete 20 as described above. The slab
concrete 4 for forming an upper floor slab is formed along a
horizontal plane above the binding beam concrete 20. Girder
concrete (reference numeral omitted) for forming the girder 2 is
formed, so as to be orthogonal to the binding beam 1, at the front
and rear ends of the binding beam concrete 20. Although the binding
beam concrete 20, the slab concrete 4, and the girder concrete are
given different names and reference numerals, the binding beam
concrete 20, the slab concrete 4, and the girder concrete are
simultaneously placed and formed in Embodiment 1. The binding beam
concrete 20, the slab concrete 4, and the girder concrete will be
simply referred to as "concrete" when no distinguishment among them
is necessary.
Configuration-Main Bar
[0048] The main bars 30 are rebars extending along the axial center
direction of the beam. Although two upper end bars and four lower
end bars are illustrated as an example in Embodiment 1, the number
and disposition of the main bars 30 are not limited thereto.
Configuration-Web Opening
[0049] The web opening 40 is a hole formed so as to penetrate the
side plate portion 13 and the binding beam concrete 20. The web
opening 40 is formed by, for example, the side plate portion 13 and
the binding beam concrete 20 being drilled with a drill after the
binding beam concrete 20 placed in the steel form 10 is solidified.
By the web opening 40 being formed as described above, a duct or
piping for air conditioning, electrical equipment, and so on can be
passed through the web opening 40 (a case where a duct for air
conditioning is passed through the web opening 40 will be described
below Accordingly, the duct can be extended from one of spaces
sandwiching the beam 1 (such as the space to the right of the
binding beam 1) to the other thereof (such as the space to the left
of the binding beam 1) and the degree of freedom of duct
disposition is improved.
[0050] The web opening 40 is formed in the web opening forming
portion of the binding beam 1. The "web opening forming portion" is
a part where the web opening 40 penetrating the side plate portion
13 and the binding beam concrete 20 can be formed. Specifically,
the "web opening forming portion" is a part where no rebar (main
bar 30 in Embodiment 1) is arranged (part where the drill does not
interfere with the rebar when the web opening 40 is drilled with
the drill). For example, in Embodiment 1, the "web opening forming
portion" is a part above the lower main bar 30 (lower end bar) in
the binding beam 1. The number of the web openings 40 is six and
the web openings 40 are along the axial center direction of the
beam in the illustration. The number of the web openings 40 is not
limited to six.
Configuration-Girder Joining Portion
[0051] The joining portion between the binding beam 1 and the
girder 2 according to Embodiment 1 will be described below. FIG. 2
is an exploded perspective view illustrating a temporary state
during construction in the vicinity of the joining portion between
the binding beam 1 and the girder 2. The concrete and the rebar
that constitute the binding beam 1 and the girder 2 are not
illustrated in FIG. 2 for convenience of illustration. As
illustrated in FIG. 2, a notch (hereinafter, referred to as binding
beam accommodating portion 2b) having a shape (hat shape)
substantially corresponding to the axial cross-sectional shape of
the binding beam 1 is formed in a side surface of a wooden form 2a
of the girder 2 according to Embodiment 1. The binding beam 1 and
the girder 2 can be formed at the same time by concrete being
simultaneously placed in the wooden form 2a of the girder 2 and the
steel form 10 with the steel form 10 of the binding beam 1 fitted
in the binding beam accommodating portion 2b. As illustrated in the
drawing, notches (hereinafter, referred to as flange accommodating
portions 2c) having the same width as the flange portion 14 are
formed on the left and right of the upper end of the binding beam
accommodating portion 2b. The flange portion 14 can be housed in
the flange accommodating portion 2c. In a case where the flange
portion 14 is housed in the flange accommodating portion 2c as
described above, a gap equivalent to the height of the reinforcing
portion 15 is formed below the flange portion 14. A sealing
material 2d (illustrated rectangular wood or the like) filling this
gap is disposed for prevention of concrete leakage from the
gap.
[0052] Temporary supports (not illustrated) may support the binding
beam 1 until concrete placement. The positions and number of the
temporary supports may be appropriately changed in accordance with
the length and weight of the binding beam 1. For example, one
temporary support may be provided in one axial end portion, one
temporary support may be provided in the other axial end portion,
and one temporary support may be provided in the axial middle
portion. The steel form 10 is higher in proof stress than the
wooden form 2a, and thus the temporary supports may be omitted if
the temporary supports are unnecessary in view of the length and
weight of the binding beam 1.
Method for Designing Steel Form
[0053] Next, an example of a method for designing the steel form 10
according to Embodiment 1 will be described. In the present
embodiment, the allowable bending moment or the allowable shear
force of the binding beam 1 is calculated by the following Equation
(1).
F.sub.a=F.sub.RC+.beta.F.sub.S (Equation 1)
[0054] F.sub.a: allowable bending moment or allowable shear force
of binding beam 1
[0055] F.sub.RC: allowable bending moment or allowable shear force
of binding beam concrete 20 (hereinafter, referred to as reinforced
concrete ("RC") as necessary)
[0056] .beta.: burden factor of allowable bending moment or
allowable shear force of steel form 10, which is 0.5 or less
[0057] F.sub.S: allowable bending moment or allowable shear force
of steel form 10
Method for Designing Steel Form-Method for Designing Allowable
Bending Moment
[0058] This design method will be divided into an allowable bending
moment design method and an allowable shear force design method and
described in further detail below. The allowable bending moment
design method will be described first. The allowable bending moment
is designed after division into a long-term allowable bending
moment and a short-term allowable bending moment. The long-term
allowable bending moment is calculated by the following Equation
(2). The short-term allowable bending moment is calculated by the
following Equation (3). FIG. 3 is a view illustrating the
relationship between the cross section of the binding beam 1 and
calculation parameters.
.sub.LM.sub.a=.sub.LM.sub.RC+.sub.L.beta..sub.M.sub.LM.sub.S
(Equation 2)
.sub.SM.sub.a=.sub.SM.sub.RC+.sub.S.beta..sub.M.sub.SM.sub.S
(Equation 3)
[0059] .sub.LM.sub.RC: long-term allowable bending moment of RC
cross section part (which may be a.sub.t.sub.Lf.sub.tj in case
where tensile rebar ratio of RC cross section is balanced rebar
ratio or less)
[0060] .sub.SM.sub.RC: short-term allowable bending moment of RC
cross section part (which may be a.sub.t.sub.Sf.sub.tj in case
where tensile rebar ratio of RC cross section is balanced rebar
ratio or less)
[0061] a.sub.t: tensile rebar cross-sectional area
[0062] .sub.Lf.sub.t: long-term allowable tensile stress of tensile
rebar
[0063] .sub.Sf.sub.t: short-term allowable tensile stress of
tensile rebar
[0064] j: stress center distance (j=(7/8)d)
[0065] d: effective depth of cross section (distance from upper
surface of binding beam 1 to concrete bar arrangement)
[0066] .sub.L.beta..sub.M: long-term steel frame bending burden
effective factor of 0.5 or less, 0.1 here
[0067] .sub.S.beta..sub.M: short-term steel frame bending burden
effective factor of 0.5 or less, 0.4 here
[0068] .sub.LM.sub.S: long-term allowable bending moment of S cross
section part (.sub.LM.sub.S=.sub.L.sigma..sub.tZ.sub.S)
[0069] .sub.SM.sub.S: short-term allowable bending moment of S
cross section part (.sub.SM.sub.S=.sub.S.sigma..sub.tZ.sub.S)
[0070] .sub.L.sigma..sub.t: long-term allowable tensile stress of
steel form 10
[0071] .sub.S.sigma..sub.t: short-term allowable tensile stress of
steel form 10
[0072] Z.sub.S: section modulus of steel form 10
[0073] An ultimate bending strength Mu is calculated by the
following Equation (4),
M.sub.u=M.sub.uRC+M.sub.uS (Equation 4)
[0074] M.sub.uRC: ultimate bending strength of RC cross section
part (M.sub.uRC=0.9a.sub.t1.1.sub.Sf.sub.td)
[0075] a.sub.t: tensile rebar cross-sectional area
[0076] .sub.Sf.sub.t: short-term allowable tensile stress of
tensile rebar
[0077] d: effective depth of cross section
[0078] M.sub.uS: ultimate bending strength of S cross section part
(M.sub.uS=1.1.sub.S.sigma..sub.tZ.sub.p)
[0079] .sub.S.sigma..sub.t: short-term allowable tensile stress of
steel form 10
[0080] Z.sub.p: plastic section modulus of steel form 10
[0081] The long-term allowable bending moment is an allowable
bending moment over a relatively long time (such as several years
to several decades). The short-term allowable bending moment is an
allowable bending moment over a relatively short time (such as
several hours to several days). The allowable bending moment is
calculated after the division into the two periods as described
above so that an allowable bending moment suitable for each load
bearing ratio is designed in view of the fact that the load bearing
ratio of the RC and the steel form 10 in the binding beam 1 can
vary as the situation of loading on the binding beam 1 can vary
with the lengths of the periods. In other words, it is assumed that
the loading on the binding beam 1 is relatively small in a
relatively long time, and thus it is assumed that the RC of the
binding beam 1 is maintained without breaking (see the lower left
cross section in FIG. 4 (described later)) and the load bearing
ratio of the RC increases. In a relatively short time, it is
assumed that the loading on the binding beam 1 is relatively large
(for example, the loading becomes relatively large by a forklift
that carries a heavy object passing through the binding beam 1),
and thus it is assumed that the load bearing ratio of the RC
decreases as a result of cracking at the lower end of the RC of the
binding beam 1 (see the lower left cross section in FIG. 5
(described later), as indicated by a diagonal line in this cross
section, it is assumed that only approximately the upper two-thirds
of the slab part of the RC remains without cracking and bears the
load). In this regard, in the present embodiment, the load bearing
ratio of the RC and the steel form 10 in the binding beam 1 is
expressed in Equations 2 and 3 as a steel frame bending burden
effective factor .beta..sub.M, and then this steel frame bending
burden effective factor .beta..sub.M is given different values in
the long-term and short-term cases and the allowable bending moment
suitable for each load bearing ratio is designed as a result. By
adopting the design method, it is possible to calculate a complex
allowable bending moment taking long-term and short-term loading
situations into account and it is possible to optimize the design
of the binding beam 1.
[0082] The steel frame bending burden effective factor .beta..sub.M
can be calculated from a bending rigidity ratio
.zeta..sub.M(=E.sub.SI.sub.S/E.sub.CI.sub.C) of the RC and a
bending rigidity E.sub.SI.sub.S of the steel form 10. The bending
rigidity ratio .zeta..sub.M can vary with the plate thickness of
the steel form 10 and the thickness of the slab concrete 4 attached
to the binding beam 1 (hereinafter, referred to as "slab" as
necessary), and thus an application restriction range is set for
each of the plate thickness of the steel form 10 and the thickness
of the slab, the bending rigidity ratio .zeta..sub.M is calculated
on the premise of the application restriction range, and the steel
frame burden effective factor .beta..sub.M is determined from the
calculated bending rigidity ratio .zeta..sub.M. Specifically, the
plate thickness of the steel form 10 has an application restriction
range of 3.2 mm or more. The load bearing ratio of the steel form
10 increases as the plate thickness of the steel form 10 increases,
and thus a lower limit value of "3.2 mm" and application
restriction range setting "at or above" the lower limit value allow
the steel frame burden effective factor .beta..sub.M to remain
above it insofar as the plate thickness of the steel form 10 is
determined in the application restriction range. The thickness of
the slab has an application restriction range of 200 mm or less.
The ratio of load bearing by the slab increases as the thickness of
the slab increases, and then the load bearing ratio of the steel
form 10 decreases. Accordingly, an upper limit value of "200 mm"
and application restriction range setting "at or below" the upper
limit value allow the steel frame burden effective factor
.beta..sub.m to remain above it insofar as the thickness of the
slab is determined in the application restriction range.
[0083] FIG. 4 is a graph showing the relationship between the
thickness of the slab and a long-term bending rigidity ratio
.sub.L.zeta..sub.M, and FIG. 5 is a graph showing the relationship
between the thickness of the slab and a short-term bending rigidity
ratio .sub.S.zeta..sub.M. In each graph, the horizontal axis
represents the thickness of the slab, the vertical axis represents
the bending rigidity ratio .zeta..sub.M (long-term bending rigidity
ratio .sub.L.zeta..sub.M or short-term bending rigidity ratio
.sub.S.zeta..sub.M), the solid line indicates a load of 3.2 tons,
and the dotted line indicates a load of 4.5 tons. It is assumed
that the cross-sectional shape of the binding beam 1 is a standard
cross section (6.5 in in total length, 300 mm in total width, and
550 mm in total height). As shown in FIG. 4, in the long term, the
long-term bending rigidity ratio .sub.L.zeta..sub.M is
approximately 0.12 at 200 mm, which is the upper limit value of the
application restriction range of the slab thickness, and thus the
long-term bending rigidity ratio .sub.L.zeta..sub.M was set to 0.1
in view of safety. As shown in FIG. 5, in the short term, the
short-term bending rigidity ratio .sub.S.zeta..sub.M is
approximately 0.49 at 200 mm, which is the upper limit value of the
application restriction range of the slab thickness, and thus the
short-term bending rigidity ratio .sub.S.zeta..sub.Mwas set to 0.4
in view of safety. Then, calculation can be performed based on the
long-term bending rigidity ratio .sub.L.zeta..sub.M of 0.1 and the
short-term bending rigidity ratio .sub.S.zeta..sub.M of 0.4 and in
accordance with proof stress formula
M.sub.a=(1+.sub.L.zeta..sub.M)M.sub.RC and steel frame bending
burden effective factor
.beta..sub.M=.zeta..sub.M(M.sub.RC/M.sub.S). Here, M.sub.RC/M.sub.S
is the allowable proof stress ratio between the RC cross section
and the steel form 10 and M.sub.RC/M.sub.S is 1.35 in a case where
the bar arrangement of the RC cross section is 4-HD13 (four
deformed rebars (steel deformed bars) having a yield point of 345
N/mm2 or more) and the plate thickness of the steel form 10 is 3.2
mm in the cross sections in FIGS. 4 and 5. Here, the steel frame
bending burden effective factor pm was calculated using
M.sub.RC/M.sub.S=1.0 as a value of safety side. As described above,
in the present embodiment, a simplified method (.beta. method) is
used in which the restriction of the application restriction range
is applied to the plate thickness of the steel form 10 and the
thickness of the slab. Alternatively, a detail method (.zeta.
method) may be adopted in which the bending rigidity ratio
.zeta..sub.M is set in accordance with each cross-sectional shape
(plate thickness of the steel form 10, slab thickness, and bar
arrangement) and the steel frame bending burden effective factor
.beta..sub.M is calculated by using proof stress formula
M.sub.a=(1+.sub.L.zeta..sub.M)M.sub.RC. Here, the design formula is
determined on the safety side so that the design formula does not
become complicated (low iron burden rate being set in terms of
design). As confirmed by the inventor's experiment, the cross
section part of the steel form 10 is restrained by the RC cross
section part and the steel form 10 undergoes no lateral buckling as
a thin plate, and thus a tensile stress f.sub.t is adopted as an
allowable stress f.sub.b of the steel material of the steel form
10.
Method for Designing Steel Form-Method for Designing Allowable
Shear Force
[0084] Next, the allowable shear force design method will be
described. The allowable shear force is designed after division
into a long-term allowable shear force and a short-term allowable
shear force similarly to the above idea related to the allowable
bending moment. The long-term allowable shear force is calculated
by the following Equation (5) and the short-term allowable shear
force is calculated by the following Equation (6). The relationship
between the cross section of the binding beam 1 and calculation
parameters is as illustrated in FIG. 3.
.sub.LQ.sub.a=.alpha.A.sub.C.sub.Lf.sub.S+.beta..sub.Q.sub.SA.sub.W.sub.-
L.sigma..sub.S (Equation 5)
.sub.SQ.sub.a=.alpha.A.sub.C.sub.Sf.sub.S+.beta..sub.Q.sub.SA.sub.W.sub.-
S.sigma..sub.s (Equation 6)
[0085] .alpha.: additional factor by shear span ratio
(M/Q.sub.d)
[0086] A.sub.C: shear effective cross-sectional area of RC portion
(A.sub.C=Bj+2B.sub.2t)
[0087] .sub.Lf.sub.s: long-term allowable shear stress of
concrete
[0088] .sub.Sf.sub.S: short-term allowable shear stress of
concrete
[0089] .beta..sub.Q: steel frame shear burden effective factor of
0.5 or less, 0.2 here
[0090] .sub.SA.sub.W: shear cross-sectional area of steel form 10
(.sub.SA.sub.W=2t.sub.S(H-2r))
[0091] t.sub.S: thickness of steel plate
[0092] r: curvature radius of corner of Z-steel plate 11
[0093] .sub.L.sigma..sub.S: long-term allowable shear stress of
steel material of Z-steel plate 11 (.sub.L.sigma..sub.S=square root
of .sub.L.sigma..sub.t/3)
[0094] .sub.S.sigma..sub.S: short-term allowable shear stress of
steel material of Z-steel plate 11 (.sub.S.sigma..sub.S=square root
of .sub.S.sigma..sub.t/3)
[0095] The shear effective cross-sectional area Ac of the RC
portion used in the shear force calculation is the same cross
section as the binding beam 1 used in the experiment as illustrated
in FIG. 3 and the cross-sectional area of the slab on the flange
portion of the steel form 10 may also be included. The steel frame
shear burden effective factor .beta..sub.Q in the shear force
calculation formula can be obtained from a shear rigidity ratio
.zeta..sub.Q of the steel form 10 indicated by the result of the
inventor's experiment. FIG. 6 is a graph showing the relationship
between the load that is applied to the binding beam 1 and the
shear rigidity ratio .zeta..sub.Q of the steel form 10, which
pertains to a case where the web opening (opening) 40 is absent.
FIG. 7 is a graph showing the relationship between the load that is
applied to the binding beam 1 and the shear rigidity ratio
.zeta..sub.Q of the steel form 10, which pertains to a case where
the web opening (opening) 40 is present. In each graph, the
horizontal axis represents the applied load and the vertical axis
represents the shear rigidity ratio .zeta..sub.Q. As is apparent
from FIGS. 6 and 7, the shear rigidity ratio .zeta..sub.Q of the
steel form 10 is substantially constant at approximately 0.2
regardless of the presence or absence of the web opening 40 and the
magnitude of the applied load. Accordingly, in the present
embodiment, the steel frame shear burden effective factor
.beta..sub.Q was obtained with shear rigidity ratio .zeta..sub.Q
set to 0.2. The steel frame shear burden effective factor
.beta..sub.Q is calculated from
.beta..sub.Q=.zeta..sub.Q(Q.sub.RC/Q.sub.S) by detail method
(.zeta. method)-based proof stress formula
Q.sub.L=(1+.sub.L.zeta..sub.Q).sub.LQ.sub.RC. Here,
Q.sub.RC/Q.sub.S is the ratio between the shear capacity of the
steel form 10 and the RC cross section. Q.sub.RC/Q.sub.S is 1.04 in
a case where the cross-sectional shape of the binding beam 1 is a
standard cross section (6.5 m in total length, 300 mm in total
width, and 550 mm in total height) and the thickness of the steel
form 10 is 3.2 mm. Here, the steel frame shear burden effective
factor .beta..sub.Q of 0.2 was calculated using
Q.sub.RC/Q.sub.S=1.0 as a value of safety side. Also in this shear
design formula, .zeta..sub.Q is constant at 0.2 as the detail
method (.zeta. method) and obtainment is also possible from
equation Q.sub.a=(1+.zeta..sub.Q)Q.sub.RC obtained from the
allowable proof stress of the RC cross section. As with the bending
design formula, however, the steel frame burden effective factor
was clarified in the design formula.
[0096] As described above, the long-term steel frame bending burden
effective factor .sub.L.beta..sub.M is 0.1 and the short-term steel
frame bending burden effective factor .sub.S.beta..sub.M is 0.4 in
the design of the allowable bending moment. In the design of the
allowable shear force, the steel frame shear burden effective
factor .beta..sub.Q is 0.2. Although the burden factor .beta. of
the steel form 10 may be another value, the upper limit of the load
bearing ratio of the steel form 10 is set to 50% and the burden
factor .beta. of the steel form 10 is set to 0.5 or less for safety
enhancement. The lower limit of the load bearing ratio of the steel
form 10 can be at least 10% in view of the graphs in FIGS. 6 and 7
and the burden factor .beta. of the steel form 10 can be set to 0.1
or more. However, the steel form 10 may be used only as a form of
the binding beam concrete 20 and the steel form 10 may be allowed
to bear no load. In this case, the burden factor .beta. of the
steel form 10 may be 0. By adopting the design method, it is
possible to calculate a complex allowable bending moment and a
complex allowable shear force taking the respective bearing ratios
of the steel form 10 and the binding beam concrete 20 into account
and it is possible to optimize the design of the binding beam
1.
Steel Form Forming Method
[0097] Next, an example of the method for forming the steel form 10
according to Embodiment 1 will be described. First, the Z-steel 11
is manufactured at a factory. The Z-steel 11 can be manufactured by
any specific method. For example, the Z-steel 11 can be formed by
bending of one flat thin steel plate. Subsequently, the
manufactured Z-steel 11 is transported to a construction site. At
this time, a plurality of the Z-steels 11 can be transported in an
overlapping manner, and thus it is possible to transport more
Z-steels 11 at one time than in the case of transporting the pair
of mutually joined Z-steels 11. Transport efficiency enhancement
can be achieved as a result.
[0098] The sealing material (small piece) 2d described with
reference to FIG. 2 may be attached to the lower part of the flange
portion 14 by any method such as adhesion before the transport. In
this case, the strength of the flange portion 14 or the reinforcing
portion 15 can be enhanced by the sealing material 2d and
deformation of the flange portion 14 or the reinforcing portion 15
attributable to a load or an impact during the transport can be
prevented. For a similar purpose, a reinforcing material (not
illustrated) similar in shape to the sealing material 2d may be
provided at a predetermined interval below the flange portion 14 or
a long reinforcing material (not illustrated) resulting from
extension of the sealing material 2d in the Y direction in FIG. 2
may be provided below the flange portion 14. Such reinforcing
materials may be removed after the transport or may be permanently
fixed without removal. The strength of the flange portion 14 or the
reinforcing portion 15 can be reduced to the same extent in a case
where the strength of the flange portion 14 or the reinforcing
portion 1.5 can be improved by such a reinforcing material being
provided, and thus the flange portion 14 and the reinforcing
portion 15 may be reduced in thickness or the dimension at which
the reinforcing portion 15 extends from the flange portion 14 may
be shortened.
[0099] Next, the pair of Z-steels 11 transported to the
construction site are joined together and the steel form 10 is
formed. Specifically, as illustrated in FIG. 1(b), the bottom plate
portions 12 of the right Z-steel and the left Z-steel are
overlapped and, in that state, a bolt may be inserted through and
fastened in each of bolt holes illustrated) formed at an
appropriate interval at the overlapping part of both bottom plate
portions 12. When both Z-steels are joined in this manner, it is
preferable to attach a member for maintaining a constant interval
between the respective side plate portions 13 of the Z-steels 11.
For example, a batten positioned in the groove portion and fixing
the interval by propping the side plate portions 13 or a U-shaped
veneer board fitted to the outer edge shape of the groove portion
may be temporarily installed and removed after both Z-steels 11 are
joined to each other.
Binding Beam Construction Method
[0100] A method for constructing the binding beam 1 according to
Embodiment 1 will be described below. FIG. 8 is a set of
cross-sectional perspective views corresponding to the A-A arrow
cross section in FIG. 1(a). FIG. 8(a) illustrates the binding beam
1 at the completion of a steel form installation step. FIG. 8(b)
illustrates the binding beam 1 at the completion of main bar
arrangement, deck plate installation, and placement steps, FIG.
8(c) illustrates the binding beam 1 at the completion of a
penetration step.
[0101] First, the steel form installation step is performed as
illustrated in FIG. 8(a). In the steel form installation step, the
steel form 10 formed by the above-described forming method is
lifted by a heavy machine or the like and installed at a beam
construction position. In Embodiment 1, the installation is
performed such that an end portion of the steel form 10 is
connected to the wooden form 2a of the girder 2 as illustrated in
FIG. 2. For convenience of illustration, the steel form 10 of the
binding beam 1 in FIG. 2 is illustrated as being tightly fit in the
notch (binding beam accommodating portion 2b) of the wooden form 2a
of the girder 2. However, the invention is not limited thereto. The
binding beam accommodating portion 2b may be enlarged in the width
direction so that insertion of the steel form 10 into the binding
beam accommodating portion 2b is facilitated and the space between
the steel form 10 and the binding beam accommodating portion 2b may
be filled with wood or the like after the insertion of the steel
form 10. After the steel form 10 is installed as described above,
the steel form 10 is supported by means of a temporary support so
as to be capable of enduring the subsequent concrete placement.
[0102] Subsequently, the main bar arrangement, deck plate
installation, and placement steps are performed as illustrated in
FIG. 8(b).
[0103] The main bars 30 are arranged in the steel form 10 in the
main bar arrangement step. Specifically, the main bars 30 are
assembled, lifted by means of a heavy machine or the like, and
dropped into and disposed in the groove portion. Likewise, the main
bars 30 (not illustrated) of the girder 2 are dropped into and
disposed in the wooden form 2a of the girder 2. Then, the main bars
30 of the binding beam 1 are bent in, for example, end portions and
fixed to the main bars 30 of the girder 2.
[0104] The deck plates 3 are installed on the flange portions 14 of
the steel form 10 in the deck plate installation step. In the deck
plate installation step, the plurality of deck plates 3 are placed
on the flange portions 14 so as to bridge one binding beam 1 and
another adjacent binding beam 1 and fixed to the flange portions 14
by bolt fastening or the like.
[0105] In the placement step, the binding beam concrete 20 is
placed in the groove portion that is configured by the pair of side
plate portions 13 and the bottom plate portion 12 of the steel form
10 installed in the steel form installation step. Specifically, in
this placement step, concrete is poured into the groove portion of
the steel form 10 while a vibrator is used for air bubble mixing
prevention. As described above, in Embodiment 1, concrete is
simultaneously placed in the wooden form 2a of the girder 2 and on
the deck plate 3, and then the binding beam 1, the girder 2, and
the slab are integrally formed.
[0106] Subsequently, the penetration step is performed as
illustrated in FIG. 8(c). Formed in the penetration step is the web
opening 40 penetrating the steel form 10 installed in the steel
form installation step and the binding beam concrete 20 placed in
the placement step. Specifically, in this penetration step, the
side plate portion 13 of one Z-steel 11, the binding beam concrete
20, and the side plate portion 13 of the other Z-steel 11 are
sequentially penetrated by means of an excavator (such as a known
drill) after the concrete placed in the placement step realizes a
predetermined strength, and the web opening 40 is formed as a
result. Then, the plurality of web openings 40 are formed by
similar work being performed in a plurality of places of the beam.
The number of the web openings 40 may correspond to the number of
ducts to be disposed.
[0107] The size and the position of disposition of the web opening
40 can be determined similarly to general RC. For example, it is
preferable that the maximum diameter of the web opening 40 is
one-third or less of the height of the binding beam 1 (dimension D
in FIG. 3), the position of disposition is other than the end
portion of the binding beam 1 (range to one-tenth of the total
length of the binding beam 1 and range equivalent to twice the
diameter of the web opening 40 from the end portion of the binding
beam 1), and the interval between the plurality of web openings 40
is at least 1.5 times the total value of the respective diameters
of the web openings 40. The size and the position of disposition of
the web opening 40 are not limited to the example and can be
determined in any manner insofar as the required strength of the
binding beam 1 can be ensured.
[0108] Lastly, a duct is passed through the web opening 40 formed
in the penetration step. The passage of the duct (not illustrated)
is performed by a known method and will not be described in detail.
This is the end of the description of the binding beam construction
method according to Embodiment 1.
Effects of Embodiment 1
[0109] As described above, in the binding beam 1 of Embodiment 1,
since the steel form 10 having the groove portion can be formed by
joining the pair of Z-steels 11 to each other on the joining
surface of the bottom plate portion 12, roll molding or press
molding of a thin steel plate for groove portion formation can be
omitted and the labor and cost required for the processing can be
reduced. Also, the groove portion can be formed by joining the pair
of Z-steels 11 to each other at a construction site, and thus the
pair of Z-steels 11 can be stacked and transported in a state where
the frame members are not joined to each other. As a result, the
number of the Z-steels 11 that can be transported at one time can
be increased and the labor and cost required for the transport can
be reduced.
[0110] In addition, it is possible to calculate a complex allowable
bending moment and a complex allowable shear force taking the
respective bearing ratios of the steel form 10 and the binding beam
concrete 20 into account and it is possible to optimize the design
of the binding beam 1.
[0111] Since the bottom plate portions 12 are joined to each other
in a state where they are overlapped at the joining surface, when
the binding beam concrete 20 is cast on the steel form 10, leakage
of the binding beam concrete 20 from the joint portion can be
suppressed, and construction is improved. Further, by directly
joining the bottom plate portions 12 each other, another plate or
the like for connecting the bottom plate portions 12 to each other
becomes unnecessary, and the cost required for joining can be
reduced.
[0112] Since the flange portion 14 is provided, the load of the
slab supported by the binding beam 1 can be received by the flange
portion 14 and is allowed to smoot flow to the binding beam 1 and
the proof stress of the binding beam 1 is improved.
[0113] Since the reinforcing portion 15 is provided at the outer
end of the flange portion 14, buckling of the flange portion 14 at
a time when the binding beam concrete 20 is placed on the groove
portion or the flange portion 14 of the steel form 10 can be
suppressed by the reinforcing portion 15 and the proof stress of
the binding beam 1 is improved.
Embodiment 2
[0114] Next, a binding beam according to Embodiment 2 will be
described. Schematically, Embodiment 2 relates to a construction
method in which a cylindrical form is pre-installed in the web
opening forming portion and a web opening is formed in the place of
cylindrical form installation by post-concrete placement
cylindrical form removal. The configuration of the binding beam
according to Embodiment 2 after completion is substantially the
same as the configuration of the binding beam according to
Embodiment 1, and regarding the configuration substantially the
same as the configuration of Embodiment 1, the same reference
numerals and/or names as those used in Embodiment 1 are attached
thereto as necessary, and a description thereof will be omitted.
The following description covers a steel form forming method and a
binding beam construction method in relation to the binding beam
according to Embodiment 2. Description will be appropriately
omitted as to procedures similar to those of Embodiment 1.
Steel Form Forming Method
[0115] First, an example of the method for forming the steel form
10 according to Embodiment 2 will be described. First, the Z-steel
11 is manufactured at a factory. At this time, a circular hole 51
is formed in advance at a position corresponding to the web opening
forming portion in the Z-steel 11. In other words, in Embodiment 2,
the circular hole 51 is provided at each of the positions six
places in total in the drawing) in the side plate portion 13 of the
Z-steel 11 that corresponds to the web opening 40 illustrated in
FIG. 1(a) by means of any tool such as a cutting machine.
Subsequently, the Z-steel 11 having the circular holes 51 as
described above is transported to a construction site, and then a
pair of the Z-steels 11 transported to the construction site are
bolt-joined together. The steel form 10 is formed as a result. The
specific method for the joining is similar to that of Embodiment 1
and will not be described in detail.
Binding Beam Construction Method
[0116] The method for constructing a binding beam 50 according to
Embodiment 2 will be described below. FIG. 9 is a set of
cross-sectional perspective views corresponding to the A-A arrow
cross section in FIG. 1(a). FIG. 9(a) illustrates the binding beam
50 at the completion of steel form installation and cylindrical
form installation steps. FIG. 9(b) illustrates the binding beam 50
at the completion of main bar arrangement, deck plate installation,
and placement steps. FIG. 9(c) illustrates the binding beam 50 at
the completion of a penetration step.
[0117] First, the steel form installation and cylindrical form
installation steps are performed as illustrated in FIG. 9(a). The
steel form installation step is similar to that of Embodiment 1 and
will not be described in detail.
[0118] In the cylindrical form installation step, a cylindrical
form 52 is inserted into the circular hole 51 formed in the steel
form 10. The axial length of the cylindrical form 52 (length in the
direction) exceeds the width of the groove portion of the steel
form 10 (length in the +X-X direction), and thus both end portions
of the cylindrical form 52 protrude to the outside from the
circular hole 51 as illustrated in the drawing. Although the
cylindrical form 52 may be hollow or solid and any material can be
used for the cylindrical form 52 insofar as the load of concrete
can be withstood, the case of a solid wooden form will be described
below. After the cylindrical form 52 is installed as described
above, the gap between the outer periphery of the cylindrical form
52 and the inner periphery of the circular hole 51 is filled with a
sealing material (not illustrated) such as putty. Concrete leakage
is deterred as a result.
[0119] Subsequently, the main bar arrangement, deck plate
installation, and placement steps are performed as illustrated in
FIG. 9(b). The main bar arrangement, deck plate installation, and
placement steps can be carried out similarly to the main bar
arrangement, deck plate installation, and placement steps according
to Embodiment 1, respectively. Accordingly, detailed descriptions
of the steps will be omitted.
[0120] Subsequently, the penetration step is performed as
illustrated in FIG. 9(c). Formed in the penetration step is the web
opening 40 penetrating the steel form 10 installed in the steel
form installation step and the concrete placed in the placement
step. Specifically, in this penetration step, the cylindrical form
52 installed in the cylindrical form installation step is removed
to the outside of the binding beam 50 after the concrete placed in
the placement step realizes a predetermined strength. As a result,
the web opening 40 is formed at the position where the cylindrical
form 52 was present (web opening forming portion). In a case where
the cylindrical form 52 is given a hollow shape, a duct can be
inserted through the hollow part of the steel form 10, and thus the
cylindrical form 52 may not be removed. In addition, a part of the
duct may be used as the cylindrical form 52.
[0121] Lastly, a duct is passed through the web opening 40 formed
in the penetration step. The passage of the duct (not illustrated)
is performed by a known method and will not be described in detail.
This is the end of the description of the method for constructing
the binding beam 50 according to Embodiment 2.
Effects of Embodiment 2
[0122] As described above, with the binding beam 50 of Embodiment
2, it is possible to form the web opening 40 simply by removing the
cylindrical form 52 Accordingly, it is possible to simplify the
work for forming the web opening 40 at a construction site.
[III] Modification Examples Regarding Embodiments
[0123] The embodiments according to the invention have been
described. However, the specific configurations and means of the
invention can be modified and improved in any manner within the
scope of the technical idea of each invention described in the
claims. Such modification examples will be described below.
Regarding Problems to be Solved and Effects of Invention
[0124] First of all, the problems to be solved by the invention and
the effects of the invention are not limited to the above and may
vary with the details of the implementation environment and
configuration of the invention, and only some of the problems
described above may be solved and only some of the effects
described above may be achieved in some cases.
Inter-Embodiment Relationship
[0125] The features of each embodiment and the features according
to each of the following modification examples may be mutually
replaced or one feature may be added to another. For example, the
web opening 40 may be formed by the method according to Embodiment
1 (with a drill or the like) at the position in the binding beam 50
where the web opening 40 is not formed after the binding beam 50 is
formed by the method according to Embodiment 2 (by pre-disposition
of the cylindrical form 52 in the web opening forming portion).
Regarding Dimensions and Materials
[0126] The dimension, shape, material, ratio, and the like of each
portion of the binding beams 1 and 50 described in the detailed
description of the invention and the drawings are merely examples,
and any other dimensions, shapes, materials, ratios, and the like
can be used as well. For example, the front-view angle that is
formed by the side plate portion 13 and the bottom plate portion
12, the front-view angle that is formed by the side plate portion
13 and the flange portion 14, and the front-view angle that is
formed by the flange portion 14 and the reinforcing portion 15 may
be obtuse angles or acute angles although each of the angles is a
right angle in each of the embodiments as illustrated in FIG.
1(b).
[0127] FIG. 10 is a set of views illustrating a state where the
Z-steel 11 is transported. FIG. 10(a) is an end view illustrating
the state of transport of the Z-steel 11 of Embodiment 1. FIG.
10(b) is an end view illustrating the state of transport of a
Z-steel 11' according to a first modification example. In a state
where the plurality of Z-steels 11 of Embodiment 1 are overlapped
as illustrated in FIG. 10(a), H (hereinafter, referred to as first
overlap dimension) an interval between one of straight lines
connecting a plurality of outermost portions on one side of the
Z-steel 11 and the straight line that is parallel to the straight
line and passes through the outermost portion of the Z-steel 11 on
the other side. As illustrated in FIG. 10(b), the Z-steel 11' in
which each of the angle formed by the side plate portion 13 and the
bottom plate portion 12 and the angle formed by the side plate
portion 13 and the flange portion 14 is an obtuse angle is assumed
as the Z-steel 11' according to the first modification example, and
in a state where a plurality of the Z-steels 11' are overlapped, H'
(hereinafter, referred to as second overlap dimension) is an
interval corresponding to the first overlap dimension H. The second
overlap dimension H' is smaller than the first overlap dimension H.
Accordingly, transport efficiency improvement can be achieved by
the Z-steel 11' being formed as in FIG. 10(b).
[0128] FIG. 1 is a set of views illustrating the steel form 10
according to a second modification example. FIG. 11(a) is a plan
view of the steel form 10 that is yet to be bent. FIG. 11(b) is a
side view of the steel form 10 that is bent. The pre-bending steel
form 10 may be formed as one flat steel plate 60 as illustrated in
FIG. 11(a). In the steel plate 60, each of a boundary line L1
between the side plate portion 13 and the bottom plate portion 12,
a boundary line L2 between the side plate portion 13 and the flange
portion 14, and a boundary line L3 between the flange portion 14
and the reinforcing portion 15 has a slit. The steel form. 10 that
is illustrated in FIG. 11(b) can be formed by bending each portion
of the steel plate 60 in the slit by means of a known device or the
like. In this case, the steel form 10 may be, for example,
transported as the flat steel plate 60 in FIG. 11(a). Accordingly,
the overlap dimension of the steel form 10 in the state of
transport decreases and transportation efficiency improvement can
be achieved.
[0129] Alternatively, the steel form 10 may be divided in one or
more places in the longitudinal direction and joined at an
installation site. The position and place of division of the steel
form 10 can be determined in any manner. For example, the steel
form 10 may be divided into a plurality of units capable of being
loaded on a transport vehicle in terms of length. It is preferable
that the position of division is a place where the moment that is
applied to the post-joining steel form 10 is small. Any joining
method is applicable to the steel form 10 after the division. For
example, a pair of the steel forms 10 brought in touch with each
other in the divided state may be connected via a connection plate
(not illustrated) provided on the outside surfaces of the side
plate portions 13 of the pair of steel forms 10. A drill screw, a
bolt, or the like can be used for fixing of the connection plate to
the side plate portion 13. In addition, when the binding beam
concrete 20 is placed in the post-joining steel form 10, it is
preferable to support the steel form 10 by using a temporary
support at the joining point of the steel form 10. By the divided
structure being adopted as described above, the manufacturing
workability and the transport efficiency of the steel form 10 can
be improved. In addition, even the binding beam 1 that has a large
span can be built by joining of a plurality of the standard-span
binding beams 1.
Regarding Girder Joining Portion
[0130] Although a case where the girder 2 is a reinforced concrete
beam has been described in each embodiment, the invention is not
limited thereto and the girder 2 may be, for example, a
steel-framed beam. FIG. 12 is a set of views illustrating the
vicinity of the joining portion between a binding beam 100 and a
girder 110 according to a third modification example. FIG. 12(a) is
a right side view and. FIG. 12(b) is a cross-sectional view taken
along arrow B-B in FIG. 12(a). As illustrated in FIG. 12. in the
third modification example, the end portion of the binding beam 100
in the axial center direction (+Y-Y direction) is joined to the
girder 110, which is a steel-framed beam. Here, a dustpan shaped
member (dustpan member) 120 having a substantially U-shaped XZ
cross section is joined by welding or the like to the side surface
of the girder 110. The binding beam 100 and the girder 110 can be
joined together by the steel form 10 of the binding beam 100 being
accommodated in the dustpan shaped member 120.
[0131] Alternatively, the swallowing width of the binding beam 1 in
the girder 110 may be further increased. FIG. 13 is a set of views
illustrating the vicinity of the joining portion between the
binding beam 1 and the girder 110 according to a fourth
modification example. FIG. 13(a) is a right side view and FIG.
13(b) is a plan view As illustrated in FIG. 13, the girder 110 is
configured as reinforced concrete and disposed in the girder 110
are a plurality of the main bars 30 disposed along the longitudinal
direction of the girder 110 and a rib 31 disposed in a direction
orthogonal to the longitudinal direction and surrounding the
plurality of main bars 30 (in FIG. 13(b), only the outermost main
bars 30 in the Y direction are illustrated among the main bars 30
for convenience of illustration). A notch 111 for causing the
girder 110 to swallow the tip of the binding beam 1 is formed in
the place in the side portion of the girder 110 that corresponds to
the binding beam 1. The binding beam 1 is disposed so as to be
orthogonal to the girder 110 and joined in part to the girder 110
via the notch 111. Specifically, the pair of side plate portions 13
of the binding beam 1 is accommodated in the girder 1 by a length
L10, which is equal to or greater than the cover thickness of the
girder 110, beyond the side surface of the girder on the binding
beam 1 side whereas the bottom plate portion 12, the flange portion
14, and the reinforcing portion 15 of the binding beam 1 stay at a
position where the end surface on the girder 110 side is
substantially flush with the side surface of girder on the binding
beam 1 side. Here, the "cover thickness" is the thickness part of
concrete that reaches the rib 31 from the side surface of the
girder 110 and is the thickness of a dimension L11 in FIG. 13. It
is possible to further improve the joining strength of the binding
beam 1 and the girder 110 by the girder 110 accommodating the
binding beam 1 to the extent of the length L10, which is equal to
or greater than the cover thickness Lil of the girder 110, as
described above.
[0132] In the example illustrated in FIG. 13, in particular,
hairpin bars 17 are swallowed by the girder 110. The hairpin bars
17 are a plurality of rod-shaped bar arrangements arranged side by
side along the X direction. For the pair of side plate portions 13
swallowed by the girder 110 to be connected to each other, the
hairpin bars 17 are passed through the arrangement holes (see
reference numeral 13a in FIG. 16 to be described later) formed in
the pair of side plate portions 13 and fixed by welding or the like
to the pair of side plate portions 13. When the hairpin bar 17 is
disposed at a position closer to the Y-direction middle position of
the girder 110 than the rib 31 (position on the -Y direction side),
in particular, the hairpin bar 17 and the pair of side plate
portions 13 surround the rib 31 at least in part. in this
structure, a movement of the hairpin bar 17 in the .+-.Y direction
is regulated by the rib 31, and thus it is possible to further
improve the joining strength of the binding beam 1 and the girder
110 by means of the bearing pressure of the hairpin bar 17 (local
compressive force). In the example illustrated in FIG. 13, it is
assumed that in the pair of side plate portions 13, only the height
part that is minimum required for disposition of a required number
of the hairpin bars 17 (three in FIG. 13) is accommodated in the
girder 110. Accordingly, the unnecessary height part has a notch 18
formed therein and notched. The binding beam 1 can be accommodated
in the girder 110 by any method. For example, concrete placement
may be performed on the steel form 10 and the form of the girder
110 in a state where the end portion of the steel form 10 is
accommodated in the form of the girder 110 via the notch portion
111 formed in the form of the girder 110 and the hairpin bar 17 is
disposed to surround the rib 31 at least in part and fixed to the
side plate portion 13.
[0133] Alternatively, the pair of side plate portions 13 may be
simply accommodated in the girder 110 with the height as it is and
without the notch 18 being provided. FIG. 14 is a right side view
illustrating the vicinity of the joining portion between the
binding beam 1 and the girder 110 according to a fifth modification
example (in the fifth modification example and sixth to eighth
modification examples, places without description are similar to
those of the fourth modification example). As illustrated in FIG.
14, in the binding beam 1, the pair of side plate portions 13
extend toward the girder 110 with the height as it is and the pair
of side plate portions 13 are accommodated in the girder 110 to the
extent of a length that is equal to or greater than the cover
thickness of the girder 110.
[0134] Alternatively, a part of the pair of side plate portions 13
and a bearing pressure effective part may be swallowed by the
girder 110. FIG. 15 is a right side view illustrating the vicinity
of the joining portion between the binding beam 1 and the girder
110 according to the sixth modification example. FIG. 16 is a
perspective view of an end portion of the steel form 10 of the
binding beam 1 in FIG. 15. As illustrated in FIGS. 15 and 16, in
the binding beam 1. the pair of side plate portions 13 extend
toward the girder 110 with the height as it is (or a part of the
bottom plate portion 12 is notched along with a part of the
reinforcing portion 15 and the flange portion 14 of the steel form
10) and the pair of side plate portions 13 are accommodated in the
girder 11.0 to the extent of the length L10, which is equal to or
greater than the cover thickness of the girder 110. In this
structure, a part of the binding beam 1 accommodated in the girder
110 needs to be provided with a part receiving the bearing pressure
of the hairpin bar 17 (bearing pressure effective part). The
bearing pressure effective part may vary with the desired bearing
pressure. For example, the width of the bearing pressure effective
part is set to approximately 100 mm (=sum of an X-direction width
L12, 50 mm, of a part of the flange portion 14 left without being
cut and an X-direction width L13, 50 mm, of a part of the bottom
plate portion 12 left without being cut). When the bearing pressure
effective part has such a width, the possibility of interference
with the rib 31 is low, and thus smooth swallowing into the girder
110 is possible.
[0135] Alternatively, the part to be swallowed in the girder 110
may be retrofitted. FIG. 17 is a right side view illustrating the
vicinity of the joining portion between the binding beam 1 and the
girder 110 according to the seventh modification example. As
illustrated in FIG. 17, the pair of side plate portions 13 in
addition to the bottom plate portion 12, the flange portion 14, and
the reinforcing portion 15 of the binding beam 1 has an end surface
on the girder 110 side staying at a position substantially flush
with the side surface of the girder 110 on the binding beam 1 side.
Here, a joining plate 19 is fixed, by any method including a drill
screw and a bolt, to the outside surfaces of the pair of side plate
portions 13 and only the joining plate 19 is accommodated in the
girder 110 by the length L11, which is equal to or greater than the
cover thickness of the girder 110, beyond the side surface of the
girder 110 on the binding beam 1 side. In this structure, it is not
necessary to perform processing such as providing of a notch for
the steel form 10 that has a complicated shape and the joining
plate 19 has only to be retrofitted in the side plate portion 13,
which leads to easy construction.
[0136] The binding beams 1 disposed on both sides of the girder 110
may be connected to each other. FIG. 18 is a side view illustrating
the vicinity of the joining portion between each binding beam 1 and
the girder 110 according to the eighth modification example. FIG.
19 is a plan view of FIG. 18. As illustrated in FIGS. 18 and 19,
provided on both sides of the girder 110 are the pair of binding
beams 1 disposed along a direction orthogonal to the longitudinal
direction of the girder 110 and the pair of binding beams 1 are
disposed at positions on the same straight line that correspond to
each other and brought in touch with the girder 110. The pair of
binding beams 1 are connected to each other via a hairpin bar 17'
fixed from above to the flange 14. Even in a case where a tensile
force is applied to the binding beam 1 in a direction away from the
girder 110, the hairpin bar 17' in this structure is capable of
countering the tensile force.
[0137] In each of the embodiments, the binding beam concrete 20 and
the girder concrete are placed at the same time. However, the
invention is not limited thereto and the binding beam concrete 20
and the girder concrete may be placed one by one. In a case where
the girder concrete is placed first, for example, the side surface
of the solidified girder concrete may be chipped into a shape (hat
shape) substantially corresponding to the axial cross-sectional
shape of the binding beams 1 and 50 and the binding beam concrete
20 may be placed after the end portion of the steel form 10 of each
of the binding beams 1 and 50 is installed at the chipped part.
Regarding Flange Portion
[0138] Although the flange portion 14 is provided in each
embodiment, the flange portion 14 may be omitted and the steel form
10 may be configured as a member having a substantially U-shaped
axial cross section. Although the flange portion 14 is provided at
the upper end of the side plate portion 13, the invention is not
limited thereto and the flange portion 14 may be provided at a
position other than the upper end (such as a position that is below
the upper end by a predetermined distance (such as several
centimeters)).
Regarding Reinforcing Portion
[0139] Although the reinforcing portion 15 is provided at the outer
end of the flange portion 14 in each embodiment, the reinforcing
portion 15 may be omitted in a case where the flange portion 14 is
capable of enduring the load of concrete. In addition, reinforcing
means for further reinforcing the flange portion 14 may be provided
in addition to or instead of the reinforcing portion 15. For
example, reinforcement may be performed by means of a reinforcing
steel plate affixed to the upper surface or the lower surface of
the flange portion 14. The steel plate may be affixed through the
forward-rearward direction of the flange portion 14 or may be
intensively affixed only to a part particularly requiring proof
stress (such as the vicinity of the middle of the flange portion 14
in the forward-rearward direction).
[0140] Alternatively, the shape of the reinforcing portion 15 may
be changed. FIG. 20 is a cross-sectional view corresponding to the
A-A arrow cross section in FIG. 1(a) and is a cross-sectional view
of a steel form 210 of a binding beam 200 according to a ninth
modification example. As illustrated in FIG. 20, the steel form 210
is provided with a second reinforcing portion 216. The second
reinforcing portion 216 is a steel plate extending from the lower
end of a reinforcing portion 215 toward a side plate portion 213.
By the second reinforcing portion 216 being provided as described
above, the local buckling of the outer end of the flange portion 14
that pertains to a case where the slab concrete 4 is placed and a
flange portion 214 receives the load of a slab can be more
effectively deterred. In addition, it is possible to reduce the
overall thickness of the steel form 210 by locally reinforcing only
a low-strength part by means of the second reinforcing portion
216.
[0141] The second reinforcing portion 216 can be provided in
another aspect as well. FIG. 21 is a cross-sectional view
corresponding to the A-A arrow cross section in FIG. 1(a) and is a
cross-sectional view of the steel form 210 of the binding beam 200
according to a tenth modification example. In the example
illustrated in FIG. 21, the second reinforcing portion 216 is
formed by the outer end of the flange portion 214 being folded back
toward the side plate portion 213 and the reinforcing portion 215
is omitted.
Regarding Z-steel
[0142] In each embodiment, the pair of Z-steels 11 are overlapped
with each other and bolt-joined. Specific methods for the joining
are not limited thereto. FIG. 22 is a set of cross-sectional views
corresponding to the A-A arrow cross section in FIG. 1(a). FIG.
22(a) is a cross-sectional view of the steel form 210 of the
binding beam 200 according to an eleventh modification example.
FIG. 22(b) is a cross-sectional view of a steel form 310 of a
binding beam 300 according to a twelfth modification example. In
other words, as illustrated in FIG. 22(a), the surfaces of bottom
plate portions 221 of a pair of Z-steels 220 that are brought in
touch with each other may be used as joining surfaces 222 and the
surfaces may be joined by welding. Alternatively, as illustrated in
FIG. 22(b), end portions of bottom plate portions 321 of a pair of
Z-steels 320 may be folded back upward, the inside surface of this
folded part 322 may be combined as a joining surface 323, and the
folded part may be joined by means of a caulking fitting 324 in
that state. Alternatively, drill screw or screw driving may be
performed from below or above on the end portions of the bottom
plate portions 321 of the pair of Z-steels 320 so that the end
portions are joined to each other. In this case, the drill screw or
the screw may be allowed to protrude by, for example, approximately
several centimeters into the inner spaces of the pair of Z-steels
220 so that the joining strength between the Z-steel 220 and the
binding beam concrete 20 placed in the inner space is further
enhanced.
Regarding Non-opening Member
[0143] A point that has been described in each embodiment is that a
temporary member (member removed before concrete placement) such as
a batten and a U-shaped veneer board is provided for fixing of the
relative positions of the pair of Z-steels 11 during the formation
of the steel form 10 (mutual joining of the pair of Z-steels 11). A
permanent member for fixing the relative positions of the pair of
Z-steels 11 (member embedded without pre-concrete placement
removal, hereinafter, referred to as non-opening member) may be
provided instead of or in addition to the temporary member. FIG. 23
is a set of cross-sectional views corresponding to the A-A arrow
cross section in FIG. 1(a). FIG. 23(a) illustrates a steel form 410
of a binding beam 400 according to a thirteenth modification
example. FIG. 23(b) illustrates a steel form 510 of a binding beam
500 according to a fourteenth modification example. in other words,
a non-opening member 422 may be provided for connection between
flange portions 421 of a pair of Z-steels 420 as illustrated in
FIG. 23(a) or a non-opening member 522 may be provided for
connection between side plate portions 521 of a pair of Z-steels
520 as illustrated in FIG. 23(b). When the relative positions of
the pairs of Z-steels 420 and 520 are fixed by means of the
non-opening members 422 and 522, it is possible to prevent the
pairs of Z-steels 420 and 520 from mutually opening outward due to
the weight of the binding beam concrete 20 after the placement of
the binding beam concrete 20.
[0144] The non-opening member 522 illustrated in FIG. 23(b), in
particular, is preferably provided in the range (range of the
dimension L12 in FIG. 23(b)) from the upper end positions of the
pair of side plate portions to the position that is below the upper
end positions by one-third of the height of the pair of side plate
portions. in a case where the pairs of Z-steels 420 and 520 are
likely to mutually open outward, the side plate portion 13 is
likely to pivot to the outside with the boundary between the bottom
plate portion 12 and the side plate portion 13 as a fulcrum, and
thus the distance between the pair of side plate portions 13 tends
to increase as the upper end of the side plate portion 13 is
approached. By the non-opening member 522 being provided in the
above-described range, however, the relative positions of the pair
of side plate portions 13 can be fixed at a position relatively
close to the upper ends of the pair of side plate portions 13, and
thus the mutual outward opening of the pair of side plate portions
13 can be more effectively prevented than in a case where the
non-opening member 522 is provided at a position below the
range.
Regarding Main Bar Arrangement Step
[0145] In each embodiment, the main bar arrangement step is
performed after the steel form installation step. However, the
invention is not limited thereto and the steel form installation
step may be performed after the main bar arrangement step. At this
time, the main bar 30 is disposed first in the main bar arrangement
step, the pair of Z-steels 11 are disposed so as to cover the main
bar 30 from below, and in a state where the bottom plate portions
12 of the pair of Z-steels 11 overlap each other, a bolt being
inserted from below through the bottom plate portion 12 and thereby
the pair of Z-steels 11 may be joined to each other.
[0146] One embodiment of the present invention provides a steel
form, which is a steel form for steel-framed concrete beam
formation, includes a pair of frame members, wherein each of the
pair of frame members is provided with a bottom plate portion and a
side plate portion extending upward from the bottom plate portion,
the bottom plate portion has a joining surface for joining the
respective bottom plate portions of the pair of frame members to
each other, and a groove portion allowing concrete placement is
formed by the respective bottom and side plate portions of the pair
of frame members.
[0147] According to this embodiment, since the steel form having
the groove portion can be formed by joining the pair of frame
members to each other on the joining surface of the bottom plate
portion, roll molding or press molding of a thin steel plate for
groove portion formation can be omitted and the labor and cost
required for the processing can be reduced. Also, the groove
portion can be formed by joining the pair of frame members to each
other at a construction site, and thus the pair of frame members
can be stacked and transported in a state where the frame members
are not joined to each other. As a result, the number of the frame
members that can be transported at one time can be increased and
the labor and cost required for the transport can be reduced.
[0148] Another embodiment of the present invention provides the
steel form according to the above embodiment, wherein an allowable
bending moment or an allowable shear three of the steel-framed
concrete beam is calculated by Equation (1) below: (Equation 1)
F.sub.a=F.sub.RC+.beta.F.sub.S wherein, F.sub.a: an allowable
bending moment or an allowable shear force of the steel-framed
concrete beam, F.sub.RC: an allowable bending moment or an
allowable shear force of the concrete, .beta.: a burden factor of
an allowable bending moment or an allowable shear force of the
steel form, which is 0.5 or less, and Fs: an allowable bending
moment or an allowable shear force of the steel form.
[0149] According to this embodiment, it is possible to calculate a
complex allowable bending moment and a complex allowable shear
force taking the respective bearing ratios of the steel form and
the concrete into account and it is possible to optimize the design
of the steel-framed concrete beam.
[0150] Another embodiment of the present invention provides the
steel form according to the above embodiment, wherein a part of the
steel-framed concrete beam is joined to a girder, and the steel
form is provided with an end portion on the girder side in a
longitudinal direction of the steel form, accommodated in the
girder via a notch formed in a side surface of the girder, and
having a length equal to or greater than a cover thickness of the
girder.
[0151] According to this embodiment, it is possible to further
improve the joining strength of a binding beam and a girder by the
girder accommodating the binding beam to the extent of the length,
which is equal to or greater than the cover thickness of the
girder.
[0152] Another embodiment of the present invention provides the
steel form according to the above embodiment, wherein a non-opening
member for fixing the pair of side plate portions to each other is
provided in a range from an upper end position of the pair of side
plate portions to a position below the upper end position by
one-third of a height of the pair of side plate portions.
[0153] According to this embodiment, since relative positions of
the pair of side plate portions can be fixed at a position
relatively close to the upper end position of the pair of side
plate portions, mutual outward opening of the pair of side plate
portions can be more effectively prevented than in a case where the
non-opening member is provided at a position below this range.
[0154] Another embodiment of the present invention provides the
steel form according to the above embodiment, wherein the steel
form is provided with a flange portion extending outward from an
upper end of the side plate portion.
[0155] According to this embodiment, since the flange portion is
provided, load of a slab supported by the steel-framed concrete
beam can be received by the flange portion and is allowed to
smoothly flow to the steel-framed concrete beam and proof stress of
the steel-framed concrete beam is improved.
[0156] Another embodiment of the present invention provides the
steel form according to the above embodiment, wherein the steel
form is provided with a reinforcing portion extending downward or
upward from an outer end of the flange portion.
[0157] According to this embodiment, since the reinforcing portion
is provided at the outer end of the flange portion, buckling of the
flange portion at a time when the concrete is placed on the groove
portion or the flange portion of the steel form can be suppressed
by the reinforcing portion and the proof stress of the steel-framed
concrete beam is improved.
REFERENCE SIGNS LIST
[0158] 1 Binding beam [0159] 2 Girder [0160] 2a Wooden form [0161]
2b Binding beam accommodating portion [0162] 2c Flange
accommodating portion [0163] 2d Sealing material [0164] 3 Deck
plate [0165] 4 Slab concrete [0166] 10 Steel form [0167] 11, 11'
Z-steel [0168] 12 Bottom plate portion [0169] 13 Side plate portion
[0170] 13a Arrangement hole [0171] 14 Flange portion [0172] 15
Reinforcing portion [0173] 16 Joining surface [0174] 17, 17'
Hairpin bar [0175] 18 Notch [0176] 19 Joining plate [0177] 20
Binding beam concrete [0178] 30 Main bar [0179] 31 Rib [0180] 40
Web opening [0181] 50 Binding beam [0182] 51 Circular hole [0183]
52 Cylindrical form [0184] 60 Steel plate [0185] 100 Binding beam
[0186] 110 Girder [0187] 111 Notch [0188] 120 Dustpan shaped member
[0189] 200 Binding beam [0190] 210 Steel form [0191] 213 Side plate
portion [0192] 214 Flange portion [0193] 215 Reinforcing portion
[0194] 216 Second reinforcing portion [0195] 220 Z-steel [0196] 221
Bottom plate portion [0197] 222 Joining surface [0198] 300 Binding
beam [0199] 310 Steel form [0200] 320 Z-steel [0201] 321 Bottom
plate portion [0202] 322 Folded part [0203] 323 Joining surface
[0204] 324 Caulking fitting [0205] 400 Binding beam [0206] 410
Steel form [0207] 420 Z-steel [0208] 421 Flange portion [0209] 422
Non-opening member [0210] 500 Binding beam [0211] 510 Steel form p0
520 Z-steel [0212] 521 Side plate portion [0213] 522 Non-opening
member
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