JP2628446B2 - How to prevent cracks in wall joints - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the seismic strength of a reinforced concrete building by performing post-processing on the structure, and for preventing cracks at wall joints.

[0002]

2. Description of the Related Art Generally, when a reinforced concrete earthquake-resistant wall or a reinforcing frame of a steel frame is attached to a space inside a space partitioned by reinforced concrete columns and beams, a shear force generated by an earthquake is applied to these walls. In this case, the data is transmitted through an anchor bolt or the like anchored to the column or the beam.

[0003] In this case, as shown in FIG.
Alternatively, the shearing force Q due to the earthquake acts around the anchor bolt E and the stud bolt F buried in the mortar D for later construction. The shearing force Q causes cracks and splits in the concrete wall after the joint. At this time, unless reinforcing bars are arranged around the anchor bolt E or the stud bolt F, the shear force is not transmitted to the concrete columns and beams due to cracks and splits at the joints.
Also, the original function of the construction wall cannot be fully exhibited.

[0004] In particular, as shown in FIG. 16, when the anchor bolt E or the stud bolt F is deformed by the shearing force Q due to the earthquake, the joint portion of the post-construction concrete shear wall C or the inside of the post-construction mortar D joint. Due to the deformation, a split crack G and a horizontal crack H occur.
In this case, the stress τA that generates the vertical crack G is much smaller than the stress τB that generates the horizontal crack H.

FIGS. 17 to 19 show a case in which spiral streaks 1 are arranged to prevent cracks. An anchor bolt E is driven into an existing concrete beam or an existing concrete column, and a spiral bar 1 is arranged in a gap between the stud bolt F erected on the earthquake-resistant steel frame J. Then, concrete or mortar D
Is installed.

As another example, a case in which ladder bars are arranged has been proposed. This is to drive anchor bolt E into existing concrete beam or existing concrete pillar,
In the gap between the stud bolt F erected on the earthquake-resistant steel frame J, the reinforcement is arranged so as to straddle the ladder. Thereafter, concrete or mortar D is cast into the space. After the poured concrete hardens, it is removed from the frame to build an earthquake-resistant concrete wall and an earthquake-resistant steel frame.

[0007]

In the above-described conventional method for preventing cracks at a wall joint, when a spiral is first laid, as shown in FIG. 17, the reinforcing bar is not provided with a tensile force TA which generates cracks. Resistance Q
1 is Q1 = TA · cos θ. Therefore, it is weaker than the case where the resistance is vertical. FIG.
Disposing the spiral streak around the anchor bolt E and the stud bolt F as shown in FIGS. 8 and 19 has a drawback that the gap is narrow and the construction is difficult.

Further, there is a case that anchor bolts cannot always be driven at regular intervals due to the arrangement of reinforcing bars in existing concrete, and there is a drawback that if arrangement of anchor bolts is disturbed, it is difficult to arrange reinforcing bars.

Further, when the ladder bars are arranged, the resistance Q1 of the reinforcing bars is vertically increased and the proof stress is increased as compared with the spiral bars, but the ladder bars are straddled around the anchor bolt E and the stud bolt F. The disadvantage is that it is difficult to perform the installation because the gap is narrow and it is not always possible to place anchor bolts etc. at regular intervals due to the arrangement of reinforcing bars in the existing concrete. Were present.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preventing cracks in a wall joint, in which the arrangement of the bars is easy, the seismic strength is increased, and the joint does not crack. Is what you do.

[0011]

According to the present invention, there is provided a method for preventing cracks in a wall joint according to the present invention, which comprises attaching an earthquake-resistant concrete wall or an earthquake-resistant steel frame to an existing reinforced concrete building by post-processing. The shape of the reinforcing member group row protruding from the seismic steel frame
A method for preventing cracks in wall joints, comprising arranging mesh reinforcing bars from both sides of the reinforcing member group row so that an axis formed is parallel to an imaginary plane to be formed , and then pouring concrete afterward.

[0012]

As described above, the method for preventing cracks in the wall joint according to the present invention is arranged so that the axis of the reinforcing member group projecting between the existing building, the earthquake-resistant concrete wall, and the earthquake-resistant steel frame is parallel to the axis. Arrange mesh reinforcement from both sides of the reinforcing member group row,
Afterwards, after-cast concrete is cast, so in particular, the mesh reinforcement is arranged so that stud bolts etc. are sandwiched from both sides, so that the arrangement work is easy without being affected by dimensional accuracy and the seismic resistance is Further, it is possible to prevent the occurrence of cracks in the wall joint.

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a construction procedure of a method for preventing cracks in a wall joint according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view thereof, and FIG. 3 is a transverse sectional view thereof. Here, the construction procedure of the present invention will be described. A mounting bracket 11 is driven into the facing surface of the existing concrete beam A or the existing concrete column B and the post-construction seismic steel frame 10, and an anchor bolt 12 is mounted on the mounting bracket 11 (see FIGS. 1 and 4).

On the other hand, stud bolts 13 which are welded in advance are provided on the earthquake-resistant steel frame 10. Such an earthquake-resistant steel frame 10 on which the stud bolts 13 are erected.
To existing concrete beam A or existing concrete column B
(See FIG. 5).

Next, in the space formed by the existing concrete beam A or the existing concrete column B and the earthquake-resistant steel frame 10, the mesh reinforcement 14 and the main reinforcement 14a are parallel to the group of reinforcing members (anchor bolts 12 and stud bolts 13). The anchor bolts 12 and the stud bolts 13 are arranged from both sides of the group (see FIG. 1).

At this time, it is not necessary to fit the mesh streaks 14 between the anchor bolts 12 and 13, so that the stapling work is easy. Thereafter, a concrete press-fitting formwork is erected in the post-construction earthquake-resistant steel frame, and concrete or mortar 15 is poured into this space. After the concrete is hardened, it is removed from the mold and a post-construction steel frame is constructed.

The seismic steel frame constructed in this manner is:
Since the resistance to the shearing force of the earthquake is increased, no crack is generated at the joint with the wall.

Next, as shown in FIGS. 7, 8, and 9, an example of constructing an earthquake-resistant concrete wall 16 by the method for preventing cracks in a wall joint according to the present invention will be described. As shown in FIG. 7, the existing metal beams A and the existing concrete columns B are also driven into the mounting surface 11 with the mounting bracket 11. A large-diameter rebar 17 having a length protruding toward the earthquake-resistant concrete wall 16 is anchored to the mounting bracket 11 or fastened with an adhesive.
Thereafter, a wall reinforcement 18 is arranged on the earthquake-resistant concrete wall (see FIG. 9).

Next, the mesh reinforcement 14 is placed in the space defined by the existing concrete beam A and the existing concrete column B and the earthquake-resistant concrete wall 16 so that the main reinforcement 14a is parallel to the large-diameter reinforcement 17 group. Arrange the bar from both sides. After the reinforcement is completed, formwork is assembled and concrete is poured. After the concrete is hardened, the formwork is separated to construct the earthquake-resistant concrete wall 16 (see FIG. 11).

FIG. 13 is a diagram showing a comparison between the conventional case and the method for preventing cracks in the wall joint of the present invention. In the figure, S
LM-0 is a case where no reinforcing bars are used for post-construction concrete and mortar joints. S4-75 is 4m in diameter
This is the case where m spiral streaks are arranged. L4-75
Shows a case where a ladder streak having a diameter of 4 mm is arranged. M4-
75 is a case where the mesh streak of the present invention having a diameter of 4 mm is arranged. Here, the vertical axis represents the applied shearing force (tf), and the horizontal axis represents the horizontal displacement δ (mm) of the joint mortar. It was found that M4-75, which is the case of the present invention, has the highest maximum proof stress, large displacement, and excellent toughness.

FIG. 14 shows a case where a reinforcing bar having a diameter of 6 mm is used. In the figure, SLM-00 is a case where no reinforcing bars are used for post-construction concrete and mortar joints. S6-100 is a case where a spiral streak having a diameter of 6 mm is arranged. L6-100 is a case where a ladder streak having a diameter of 6 mm is arranged. M6-100 is a case where the mesh streak of the present invention having a diameter of 6 mm is arranged. As a result,
It can be seen that L6-100 of the ladder has the largest maximum proof stress.

Although the M6-100 of the present invention has a 12% lower maximum yield strength than L6-100,
The horizontal displacement of the mortar at this time is the largest, and the displacement can be 2.7 times as large as that without the reinforcing bar, and about 1.7 times as large as the L6-100 using the ladder bar. Therefore, it is understood that the toughness is excellent and cracks are hardly generated.

The present invention is not limited to the above-described embodiment, and various design changes can be made based on the technical concept of the present invention.

[0024]

As described above in detail, the method for preventing cracks in a wall joint according to the present invention is a method for attaching an earthquake-resistant concrete wall and an earthquake-resistant steel frame to an existing reinforced concrete building by post-processing. A mesh bar is arranged from both sides of the reinforcing member group row so that an axis is parallel to an imaginary plane formed by the reinforcing member group row protruding between the earthquake-resistant concrete wall and the earthquake-resistant steel frame. Since the concrete is cast, it is not necessary to arrange the mesh reinforcements between the stud bolts and the anchor bolts, and the arrangement work is extremely easy.

[0025] Further, since the mesh streaks generate a resistance perpendicular to the shearing force caused by the earthquake, they have superior seismic strength compared to the spiral streaks, and also prevent the occurrence of cracks at the wall joints. I can do things.

Furthermore, the mounting bracket may not always be able to be driven at regular intervals due to the arrangement of the reinforcing bars in the existing concrete. In the case of the conventional spiral bars, if the arrangement of the anchor bolts is disturbed, it is difficult to arrange the reinforcing bars. According to the method for preventing cracks in a wall joint of the present invention, construction can be performed regardless of the arrangement of anchor bolts. Further, the mesh streaks can be easily processed by cutting a commercially available mesh into appropriate dimensions.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a construction procedure of a method for preventing cracks in a wall joint according to one embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a construction procedure of a method for preventing cracks in a wall joint according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a construction procedure of a method for preventing cracks in a wall joint according to one embodiment of the present invention.

FIG. 4 is a front view showing a construction procedure of a method for preventing cracks in a wall joint according to one embodiment of the present invention.

FIG. 5 is a front view showing an embodiment of a method for preventing cracks in a wall joint according to the present invention.

FIG. 6 is a front view showing one embodiment of a method for preventing cracks in a wall joint according to the present invention.

FIG. 7 is a front view showing a state where construction is being performed by the method for preventing cracks in a wall joint according to the present invention.

FIG. 8 is a sectional view showing an earthquake-resistant wall constructed by the method for preventing cracks in a wall joint according to the present invention.

FIG. 9 is a front view showing an earthquake-resistant wall in the middle of being constructed by the method for preventing cracks in a wall joint according to the present invention.

FIG. 10 is a front view showing an earthquake-resistant wall in the middle of being constructed by the method for preventing cracks in a wall joint according to the present invention.

FIG. 11 is a front view showing an earthquake-resistant wall constructed by the method for preventing a wall joint from cracking according to the present invention.

FIG. 12 is a cross-sectional view showing the relationship between the tensile force due to cracking and the resistance of a reinforcing bar by the method for preventing cracking of a wall joint according to the present invention.

FIG. 13 is a drawing comparing a method for preventing cracks in a wall joint according to the present invention with a conventional construction method (when using a 4 mm-diameter reinforcing steel).

FIG. 14 is a drawing comparing a method for preventing cracks in a wall joint of the present invention with a conventional construction method (when using a reinforcing bar having a diameter of 6 mm).

FIG. 15 is a stress distribution diagram when anchor bolts and stud bolts receive shearing force due to seismic force.

FIG. 16 is a diagram showing cracks and stress distribution of post-construction concrete and the like generated by deformation of anchor bolts and stud bolts due to seismic force.

FIG. 17 is a diagram showing the relationship between cracking and resistance using conventional spiral streaks.

FIG. 18 is a longitudinal sectional view showing a case where a conventional spiral muscle is used.

FIG. 19 is a cross-sectional view showing a case where a conventional spiral muscle is used.

[Explanation of symbols]

 A Existing Concrete Beam B Existing Concrete Column E Anchor Bolt F Stud Bolt I Reinforcing Bar 10 Earthquake Resistant Steel Frame 11 Mounting Bracket 12 Anchor Bolt 13 Stud Bolt 14 Mesh Bar 14a Main Bar 14b Secondary Bar 15 Concrete, Mortar 16 Earthquake Resistant Concrete Wall 17 Large Diameter Steel Bar 18 Wall streaks

Claims (1)

(57) [Claims] 1. A method of attaching an earthquake-resistant concrete wall or an earthquake-resistant steel frame to an existing reinforced concrete building by post-construction, forming a reinforcing member group row protruding between the existing building and the earthquake-resistant concrete wall or the earthquake-resistant steel frame. Tentative
A method for preventing cracks in a wall joint, comprising arranging mesh reinforcing bars from both sides of the reinforcing member group row so that the imaginary surface and the axis are parallel to each other, and thereafter pouring concrete afterward.