U.S. patent application number 15/882049 was filed with the patent office on 2018-11-01 for reinforcement steel.
The applicant listed for this patent is ONO KOGYOSYO CO., LTD.. Invention is credited to Akihiko TAKAHASHI, Yuichi YASHIRO.
Application Number | 20180313084 15/882049 |
Document ID | / |
Family ID | 63915581 |
Filed Date | 2018-11-01 |
United States Patent
Application |
20180313084 |
Kind Code |
A1 |
TAKAHASHI; Akihiko ; et
al. |
November 1, 2018 |
REINFORCEMENT STEEL
Abstract
A reinforcement steel bar includes a shaft part and a head part
formed by forging an end portion of the shaft part. The head part
is provided with a projection projecting from the shaft part in a
radial direction of the shaft part, and a recess formed along a
corner portion between an outer peripheral surface of the shaft
part and the projection.
Inventors: |
TAKAHASHI; Akihiko;
(Fukushima, JP) ; YASHIRO; Yuichi; (Ibaraki,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ONO KOGYOSYO CO., LTD. |
Fukushima |
|
JP |
|
|
Family ID: |
63915581 |
Appl. No.: |
15/882049 |
Filed: |
January 29, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04C 5/166 20130101;
E04C 5/12 20130101; E04C 5/03 20130101 |
International
Class: |
E04C 5/03 20060101
E04C005/03; E04C 5/12 20060101 E04C005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2017 |
JP |
2017-087620 |
Claims
1. Reinforcement steel comprising: a shaft part; and a forged head
part provided at an end portion of the shaft part, wherein the head
part is provided with a projection projecting from the shaft part
in a radial direction of the shaft part, and a recess formed along
a corner portion between an outer peripheral surface of the shaft
part and the projection, wherein a rib is formed on an outer
peripheral surface of the shaft part.
2. The reinforcement steel according to claim 1, wherein a bottom
surface of the recess is formed to be curved.
3.-4. (canceled)
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to reinforcement steel.
2. Description of the Related Art
[0002] A coupling structure for coupling decks laid on a bridge is
configured such that a reinforcement steel bar of one of the decks
and a reinforcement steel bar of the other deck are caused to
project to a space between the decks, and concrete is placed in the
space.
[0003] There is an example of reinforcement steel used in a
ferroconcrete structure such as the aforementioned deck coupling
structure, in which a diameter of a head part of the reinforcement
steel is expanded more than a diameter of a shaft part thereof (see
Japanese Patent Application Publication No. 2005-139650, for
example).
SUMMARY OF THE INVENTION
[0004] The conventional ferroconcrete structure described above
allows to increase the anchoring force to concrete against the
tensile force applied in the axial direction of the reinforcement
steel buried in the concrete since the head portion of the
reinforcement steel is engaged with the concrete. However, the
conventional ferroconcrete structure still has a problem that the
fatigue resistance of the joint portion of the head portion and the
axial portion is decreased since a stress is likely to be
concentrated on the corner portion between the head portion and the
outer peripheral surface of the axial portion when bending tensile
force or punching shearing force is applied to the reinforcement
steel.
[0005] An object of the present invention is to solve the
aforementioned problem by providing reinforcement steel which is
capable of increasing an anchoring force to concrete and enhancing
the fatigue resistance of the reinforcement steel.
[0006] To solve the problem, the present invention provides
reinforcement steel which includes a shaft part and a head part
formed by forging an end portion of the shaft part. The head part
is provided with a projection projecting from the shaft part in a
radial direction of the shaft part, and a recess formed along a
corner portion between the outer peripheral surface of the shaft
part and the projection.
[0007] According to the present invention, when a stress
attributable to a bending tensile force and to a punching shear
force is applied to the reinforcement steel buried in concrete, the
projection of the head part engages with the concrete. Thus, it is
possible to increase an anchoring force to the concrete.
[0008] Here, the anchoring force to the concrete can further be
increased when the above-described reinforcement steel is deformed
reinforcement steel provided with ribs on an outer peripheral
surface of the shaft part.
[0009] Further, the reinforcement steel of the present invention is
provided with a recess formed along a corner portion between the
projection and an outer peripheral surface of the shaft part.
[0010] In this way, a stress is less likely to be concentrated on
the corner portion between the projection and the outer peripheral
surface of the shaft part when a tensile force in the axial
direction is applied to the reinforcement steel buried in the
concrete. Thus, it is possible to increase fatigue resistance at a
junction between the head part and the shaft part.
[0011] In the case where the bottom surface of the recess is formed
to be curved in the reinforcement steel in the present invention, a
stress is less likely to be concentrated on the corner portion
between the projection and the outer peripheral surface of the
shaft part. Thus, it is possible to efficiently increase fatigue
resistance at a junction between the head part and the shaft
part.
[0012] The reinforcement steel of the present invention is capable
of increasing the anchoring force to the concrete. The
reinforcement steel of the present invention also allows to
increase the fatigue resistance of the reinforcement steel since a
stress is less likely to be concentrated on the corner portion
between the projection and the outer peripheral surface of the
shaft part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view showing reinforcement steel
according to a first embodiment of the present invention.
[0014] FIG. 2A is a plan view, FIG. 2B is a side view, and FIG. 2C
is a partial cross-sectional view showing the reinforcement steel
according to the first embodiment of the present invention.
[0015] FIG. 3A is a front view and FIG. 3B is a rear view showing
the reinforcement steel according to the first embodiment of the
present invention.
[0016] FIG. 4 is a transverse sectional view showing a coupling
structure using the reinforcement steel according to the first
embodiment of the present invention.
[0017] FIG. 5A is a perspective view showing reinforcement steel
according to a second embodiment of the present invention; and
[0018] FIG. 5B is a perspective view showing reinforcement steel
according to a third embodiment of the present invention.
[0019] FIG. 6 is a transverse sectional view showing a coupling
structure using the reinforcement steel according to the second
embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] Embodiments of the present invention will be described in
detail with reference to the drawings as appropriate.
[0021] Note that in the description of the embodiments, the same
constituents are denoted by the same reference numerals and
overlapping explanations thereof will be omitted.
First Embodiment
[0022] As shown in FIG. 1, a reinforcement steel bar 1A of a first
embodiment is deformed reinforcement steel made of steel. The
reinforcement steel bar 1A includes a shaft part 10 and a head part
20 formed at a front end portion of the shaft part 10.
[0023] The shaft part 10 is formed by providing grid ribs 11 on an
outer peripheral surface of a rod-shaped member having a circular
cross section. Accordingly, the ribs 11 form asperities on the
outer peripheral surface of the shaft part 10.
[0024] As shown in FIG. 2C, the head part 20 is formed at the front
end portion of the shaft part 10. The head part 20 is a forged
region of the front end portion of the shaft part 10. In other
words, the shaft part 10 and the head part 20 constitute an
integrated member.
[0025] An expanded-diameter part 12 having a diameter which is
expanded from that in a region on a base end side is formed at an
end portion on the head part 20 side of the shaft part 10. The
expanded-diameter part 12 is a region of the shaft part 10 having
the diameter being expanded by a pressure applied to a front end
portion of the shaft part when forging the shaft part 10 to the
head part 20.
[0026] In the first embodiment, an outer peripheral surface of the
expanded-diameter part 12 is formed substantially at the same level
as that of top surfaces of the ribs 11. Moreover, a maximum radius
of the shaft part 10 is equal to a radius of the expanded-diameter
part 12.
[0027] As shown in FIG. 1, the head part 20 is provided with: right
and left projections 21 projecting from the outer peripheral
surface of the shaft part 10 in a radial direction of the shaft
part 10; upper and lower flat surfaces 22 extending parallel to an
axial direction of the shaft part 10; and a front end surface
23.
[0028] As shown in FIG. 2A, the right and left projections 21 are
regions that project in the right-left direction from the shaft
part 10. In the first embodiment, amounts of projection of the
right and left projections 21 from the outer peripheral surface of
the shaft part 10 are substantially equal to each other. As shown
in FIG. 3A, a side surface of each projection 21 is curved into a
semicircular shape. As described above, the right and left
projections 21 have substantially laterally symmetrical shapes in
the first embodiment. However, the right and left projections 21
may have different shapes instead.
[0029] As shown in FIG. 2A, a base end surface 24 is formed at an
end portion on the shaft part 10 side of each projection 21. The
base end surface 24 is a flat surface that intersects with the
axial direction of the shaft part 10. In the first embodiment, the
outer peripheral surface of the shaft part 10 is located
substantially perpendicular to the base end surface 24.
[0030] The front end surface 23 is formed at a front end portion of
the head part 20. The front end surface 23 is a flat surface that
intersects with the axial direction of the shaft part 10. In the
first embodiment, the front end surface 23 is formed into a
rectangle in front view as shown in FIG. 3A. Here, the shape of the
front end surface 23 is not limited to a particular shape, and the
front end surface 23 may be formed into an oval shape or a circular
shape. Nonetheless, it is preferable to form the front end surface
23 into the rectangular shape so as to increase an axial
cross-sectional area of the head part 20 and thus to increase shear
strength thereof.
[0031] As shown in FIG. 2A, the head part 20 is formed such that
the amounts of projection of the projections 21 are gradually
reduced from the base end surface 24 to the front end surface 23.
In the meantime, the right and left projections 21 form the
substantially bilaterally symmetrical shape. That is to say, the
head part 20 is formed to have the front end side smaller than the
base end side, and into a substantially trapezoidal shape in plan
view.
[0032] As shown in FIG. 1, the head part 20 is provided with an
upper flat surface 22 and a lower flat surface 22. The upper and
lower flat surfaces 22 are formed into the same shape which is a
substantially trapezoidal shape.
[0033] As shown in FIG. 2B, the upper and lower flat surfaces 22
intersect with a direction (an up-down direction) which is
orthogonal to the axial direction of the shaft part 10, and the
upper and lower flat surfaces 22 are substantially parallel to each
other.
[0034] In the reinforcement steel bar 1A of the first embodiment, a
distance (a distance in the radial direction of the shaft part 10)
from the shaft center (the axis) of the shaft part 10 to each flat
surface 22 is the same as the radius of the expanded-diameter part
12. In other words, each flat surface 22 is not located outside of
the outer peripheral surface of the shaft part 10.
[0035] Here, the distance in the radial direction of the shaft part
10 from the shaft center of the shaft part 10 to each flat surface
22 is set in a range from 100% to 115% of the maximum radius of the
shaft part 10 (the radius of the expanded-diameter part 12). This
makes it possible to hold the distance within a range of a
manufacturing error when forging the head part 20.
[0036] Meanwhile, by setting the distance from the shaft center of
the shaft part 10 to each flat surface 22 equal to or more than
100% of the maximum radius of the shaft part 10, it is possible to
sufficiently secure the anchoring force of the head part 20 and to
prevent the head part 20 from deterioration in strength.
[0037] In the meantime, by setting the distance from the shaft
center of the shaft part 10 to each flat surface 22 equal to or
less than 115% of the maximum radius of the shaft part 10, it is
possible to prevent each flat surface 22 from being located largely
outside of the outer peripheral surface of the shaft part 10.
[0038] As shown in FIG. 1, a recess 25 is formed along a corner
portion between the base end surface 24 of each projection 21 and
the outer peripheral surface of the shaft part 10.
[0039] Each recess 25 is a region of the base end surface 24
recessed along an outer peripheral edge portion of the shaft part
10. A bottom surface of the recess 25 is formed into a curved
surface.
[0040] In the first embodiment, the recesses 25 are formed in the
base end surfaces 24 at the time of forging the front end portion
of the shaft part 10 to the head part 20.
[0041] Note that the method of forming the recesses 25 in the base
end surfaces 24 is not limited to a particular method. However,
when the recesses 25 are formed at the timing of forging, it is
possible to retain the strength of the head part 20 because
metallic fibers (fiber flows) of the head part 20 are not cut off
in this case.
[0042] Next, a coupling structure for decks 110 by using the
reinforcement steel bar 1A of the first embodiment will be
described.
[0043] As shown in FIG. 4, the first embodiment will describe a
coupling structure for coupling the decks 110 laid on a bridge
superstructure 100 that includes RC decks.
[0044] The decks 110 that are adjacent to each other are placed on
bridge beams with an interval in between. Thus, a space 200 is
defined between the adjacent decks 110.
[0045] Each deck 110 is a precast member made of ferroconcrete. The
reinforcement steel bar 1A of the first embodiment is laid inside
the deck 110. Moreover, a region on the front end side of the
reinforcement steel bar 1A projects in a horizontal direction from
an end surface of the deck 110.
[0046] The upper flat surface 22 of the head part 20 of the
reinforcement steel bar 1A is directed upward while the lower flat
surface 22 of the head part 20 thereof directed downward.
[0047] Meanwhile, other reinforcement steel bars 2 are disposed
between the reinforcement steel bar 1A projecting from one of the
decks 110 and the reinforcement steel bar 1A projecting from the
other deck 110.
[0048] After the reinforcement steel bars 1A are laid in the space
200 as described above, concrete C is placed in the space 200 to
bury the reinforcement steel bars 1A in the concrete C.
[0049] Then, the reinforcement steel bars 1A in the decks 110 are
anchored to the concrete C, whereby the adjacent decks 110 are
coupled to each other through the intermediary of the concrete
C.
[0050] In the above-described reinforcement steel bar 1A, when a
tensile force in the axial direction is applied to the
reinforcement steel bar 1A in the state of being buried in the
concrete C, the projections 21 of the head part 20 as well as the
ribs 11 on the shaft part 10 engage with the concrete C. Thus, it
is possible to increase the anchoring force of the reinforcement
steel bar 1A to the concrete C.
[0051] As shown in FIG. 1, in the head part 20 of the reinforcement
steel bar 1A of the first embodiment, the recess 25 is formed along
the corner portion between each projection 21 and the outer
peripheral surface of the shaft part 10. Moreover, in the first
embodiment, the bottom surface of each recess 25 is formed into the
curved surface as shown in FIG. 2C.
[0052] Accordingly, in the reinforcement steel bar 1A of the first
embodiment, when a stress attributable to a bending tensile force
and to a punching shear force is applied to the reinforcement steel
bar 1A as shown in FIG. 4, the stress is less likely to be
concentrated on the corner portion between the projection 21 and
the outer peripheral surface of the shaft part 10. Thus, it is
possible to increase fatigue resistance at a junction between the
head part 20 and the shaft part 10.
[0053] In the reinforcement steel bar 1A of the first embodiment,
if one of the upper and lower flat surfaces 22 of the head part 20
is directed to an upper surface or a lower surface of the concrete
C, then a covering depth T1 of the flat surface 22 of the head part
20 is subject to the regulation of a covering depth of the entire
reinforcement steel bar 1A.
[0054] Moreover, the covering depth of the flat surface 22 of the
head part 20 becomes substantially the same as a covering depth T2
of the shaft part 10. As a consequence, it is possible to control
the covering depth of the entire reinforcement steel bar 1A, and
thus to reduce the weight of the superstructure 100.
[0055] Although the first embodiment of the present invention has
been described above, the present invention is not limited to the
above-described first embodiment but can be changed as appropriate
within the range not departing from the scope thereof.
[0056] In the reinforcement steel bar 1A of the first embodiment,
the head part 20 is provided with the upper and lower flat surfaces
22 as shown in FIG. 1. However, the head part 20 may be provided
with one flat surface 22 and the shape of the head part 20 is not
limited to a particular shape.
[0057] In the first embodiment, each recess 25 is formed
continuously into an arc shape along the outer peripheral surface
of the shaft part 10 as shown in FIG. 3B. However, the width and
depth of the recess 25 are not limited to particular values.
Meanwhile, the recess 25 may be formed discontinuously instead.
[0058] In the meantime, the bottom surface of the recess 25 of the
first embodiment is formed into the curved surface as shown in FIG.
2C. However, the shape of the recess 25 is not limited to a
particular shape, and its cross section may be rectangular or
triangular.
[0059] In the first embodiment, the ribs 11 are formed on the outer
peripheral surface of the shaft part 10 as shown in FIG. 1.
However, the ribs 11 need not be formed on the outer peripheral
surface of the shaft part 10. That is to say, the shaft part 10 may
be formed of a round rod.
[0060] While the first embodiment has described the structure for
coupling the decks 110 to each other as shown in FIG. 3, the
structure that can apply the reinforcement steel of the present
invention is not limited thereto, and the present invention is
applicable to various ferroconcrete structures.
[0061] In the first embodiment, the reinforcement steel bars 1A are
laid in a direction of extension of the superstructure 100.
Instead, the reinforcement steel bars 1A may be laid in a width
direction of the superstructure 100 so as to connect decks that are
juxtaposed in the width direction of the superstructure 100.
Moreover, the layout structure of the reinforcement steel bars 1A
including orientations, positions, and the like thereof are not
limited. For example, the reinforcement steel bars 1 may be
disposed below the other reinforcement steel bars 2.
Second Embodiment
[0062] Next, a reinforcement steel bar 1B of a second embodiment
will be described.
[0063] As shown in FIG. 5A, the reinforcement steel bar 1B of the
second embodiment has substantially the same configuration as that
of the reinforcement steel bar 1A of the above-described first
embodiment (see FIG. 1), except that the shapes of the head parts
20 are different from each other. In the reinforcement steel bar 1B
of the second embodiment, the head part 20 is provided with a
single flat surface 22.
[0064] Moreover, in the reinforcement steel bar 1B of the second
embodiment, it is possible to control the covering depth of the
concrete C by directing the flat surface 22 toward the
corresponding one of the upper surface and the lower surface of the
concrete C as shown in FIG. 6. In addition, the reinforcement steel
bar 1B of the second embodiment has the larger projection 21. Thus,
it is possible to increase the anchoring force of the reinforcement
steel bar 1B to the concrete.
[0065] Furthermore, in the reinforcement steel bar 1B of the second
embodiment, the projection 21 projects toward the inside of the
concrete C (toward the other reinforcement steel bars 2).
Accordingly, even if the reinforcement steel bar 1B moves inside
the concrete C, it is possible to suppress a displacement of the
reinforcement steel bar 1B by allowing the projection 21 to get
stuck with the other reinforcement steel bars 2.
[0066] Although the second embodiment of the present invention has
been described above, the present invention is not limited to the
above-described second embodiment but can be changed as appropriate
within the range not departing from the scope thereof as has been
mentioned in regard to the first embodiment.
Third Embodiment
[0067] Next, a reinforcement steel bar 1C of a third embodiment
will be described.
[0068] As shown in FIG. 5B, the reinforcement steel bar 1C of the
third embodiment has substantially the same configuration as that
of the reinforcement steel bar 1A, 1B of the above-described first
and second embodiments (see FIG. 1 and FIG. 5A), except that the
shapes of the head parts 20 are different from those of the first
and second embodiments. In the reinforcement steel bar 1C of the
third embodiment, the outer peripheral surface of the head part 20
is formed to be a circular shape.
[0069] In the reinforcement steel bar 1C of the third embodiment,
the projection 21 is formed to be larger. Thus, it is possible to
increase the anchoring force of the reinforcement steel bar 1C to
the concrete.
[0070] Although the third embodiment of the present invention has
been described above, the present invention is not limited to the
above-described third embodiment but can be changed as appropriate
within the range not departing from the scope thereof as has been
mentioned in regard to the first and second embodiments.
* * * * *