JP6987577B2 - How to repair concrete structures - Google Patents

Description

The present invention relates to a method for repairing a concrete structure. More specifically, the present invention relates to a technique suitable for use in repairing / restoring a reinforced concrete surface member or wall-type structure in which shear failure has occurred, for example.

As a conventional reinforcement technique for reinforced concrete columns, a plurality of enclosed steel plates (1), which are partially overlapped and slidable from each other, have no gap between the lower end and the slab floor, and the upper end and the upper part are formed. A plurality of enclosed steel plates (2) in which a gap portion is provided between the body and the reinforced concrete column to surround the circumference of the reinforced concrete column, and the gap portion is overlapped and slidable from each other. No gap portion is provided between the two, and the outer periphery of the enclosed steel plate (1) is overlapped with the upper portion thereof and enclosed, and a strip-shaped continuous fiber sheet is wound around these enclosed steel plates to bind them, while the enclosed steel plates (1) and (2). ) And a reinforced concrete column by injecting a grout material into the space provided (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-234603

However, since the reinforcing technique of Patent Document 1 surrounds a concrete column with a steel plate (in other words, it is rolled up), it can be applied to a concrete column member, but it is made of concrete. For example, there is a problem that it cannot be applied to a surface member such as a partition wall of a box culvert or a wall-type structure.

Further, the reinforcing technique of Patent Document 1 is assumed to be applied to a concrete column which is in a sound state before being damaged or broken, that is, it is applied to a concrete member in which shear failure has occurred, for example. There is a problem that this is not expected. However, even if a concrete structure is damaged by an earthquake, for example, a restoration method that can enable continuous use without rebuilding the structure, specifically, a restoration method for a structure that has been shear-broken. It is important to consider and prepare.

Therefore, it is an object of the present invention to provide a repair method for a concrete structure capable of repairing and restoring a reinforced concrete surface member / wall structure in which shear failure has occurred while reinforcing it by post-construction.

In order to achieve such an object, the method for repairing a concrete structure of the present invention is made of reinforced concrete by forming a through hole penetrating a member made of reinforced concrete in which shear failure has occurred and inserting a reinforcing bar into the through hole. A separate plate member and nut are attached to each of both ends of the reinforcing bar protruding from the member, and an inclined washer is further arranged between the reinforced concrete member and the plate member. I have to.

Therefore, according to this method of repairing a concrete structure, a separate plate member is attached to each of both ends of the reinforcing bar, and a steel plate surrounds the reinforced concrete member of the concrete structure. Since it is not a thing, it can be applied to face members and wall-type structures such as various walls made of reinforced concrete. In addition, since the plate member properly restrains the reinforced concrete member from protruding in the out-of-plane direction, the function of reinforcing and repairing the reinforced concrete member in which shear failure has occurred is well exhibited. Ru.

According to this method for repairing concrete structures, and when applied to a member made of reinforced concrete in which shear failure has occurred, the yield strength of the member is restored, which is a method confirmed by the inventor. Reinforced concrete members will be repaired while being reinforced by construction.

Further, in the method for repairing a concrete structure of the present invention, at least a part of the through holes may be provided so as to pass through shear cracks generated in a member made of reinforced concrete due to shear fracture. In this case, since the arrangement position of the reinforcing bar to be inserted into the through hole is appropriately set, the function of repairing the reinforced concrete member in which the shear failure has occurred while being reinforced is satisfactorily exhibited. ..

Further, in the method of repairing a concrete structure of the present invention, when a plurality of through holes are formed, the arrangement interval of these through holes along the vertical direction may be set to be equal to or less than the thickness of the reinforced concrete member. In this case, since the arrangement interval of the reinforcing bars inserted into the through holes is appropriately set, the function of repairing the reinforced concrete member in which the shear failure has occurred while being reinforced is well exhibited. ..

According to the method for repairing a concrete structure of the present invention, it can be applied to various surface members such as walls made of reinforced concrete and wall-type structures, so that a method of surrounding the circumference with a steel plate cannot be applied. Can be repaired. In addition, by disposing the inclined washer, the function of repairing the reinforced concrete member in which shear failure has occurred can be satisfactorily exhibited, so that the broken member can be repaired more firmly. As a result, it becomes possible to improve the reliability as a repair method for concrete structures.

According to the method for repairing a concrete structure of the present invention, it is also possible to repair a member made of reinforced concrete that has been shear-broken while appropriately reinforcing it by post-construction.

In the method for repairing a concrete structure of the present invention, when the through holes are provided so as to pass through the shear cracks, the vertical distance between the through holes is set to be less than or equal to the thickness of the reinforced concrete member. In that case, since the function of repairing the reinforced concrete member in which shear failure has occurred can be satisfactorily exhibited, it becomes possible to repair the broken member more firmly, and eventually the concrete structure. It becomes possible to improve the reliability as a method of repairing an object.

It is a figure explaining an example of the embodiment of the repair method of the concrete structure of this invention, and is the figure which shows the situation of the partition wall to which this invention is applied in the plan view orthogonal to the direction of the road space of a box culvert. Is. It is a figure explaining the structure which is attached to the end part of a reinforcing bar and a plate member, and is the vertical sectional view along the axial direction of a reinforcing bar. It is a figure explaining the structure which is attached to the end part of a reinforcing bar and a plate member, and is the top view which is orthogonal to the axial direction of a reinforcing bar. It is a figure explaining the structure | .. It is a figure explaining the test body in Example 1, and is the elevation view (left half) and the vertical cross-sectional reinforcement arrangement (right half) orthogonal to the direction of the road space of box culvert. FIG. 5 is a cross-sectional view taken along the line AA of the test piece shown in FIG. 5A. It is a figure which shows the relationship between the horizontal displacement and the horizontal load by loading (that is, secondary loading) after repair in Example 1. FIG. It is a figure which shows the strain of the reinforcing bar at the time of loading after repair in Example 1 (specifically, the peak time of the first round on the negative side of a secondary loading). It is a figure explaining the test piece in Example 2, and is the figure explaining the test piece whose design failure mode is shear compression failure. (A) is a vertical sectional view in the longitudinal axis direction of the member. (B) is a vertical sectional view in a direction orthogonal to the longitudinal axis direction of the member. It is a figure explaining the test body in Example 2, and is the figure explaining the test body which the design failure mode is diagonal tensile failure. (A) is a vertical sectional view in the longitudinal axis direction of the member. (B) is a vertical sectional view in a direction orthogonal to the longitudinal axis direction of the member. It is a figure which shows the load-displacement relationship obtained as a result of the loading experiment in Example 2, and is the figure which shows the result when the design failure mode is diagonal tensile failure and the present invention is not applied. It is a figure which shows the load-displacement relationship obtained as a result of the loading experiment in Example 2, and is the figure which shows the result when the design failure mode is shear compression failure and the present invention is not applied. It is a figure which shows the load-displacement relationship obtained as a result of the loading experiment in Example 2, and is the figure which shows the result when the design failure mode is diagonal tensile failure and the present invention is applied. It is a figure which shows the load-displacement relationship obtained as a result of the loading experiment in Example 2, and is the figure which shows the result when the design failure mode is shear compression failure and the present invention is applied.

Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

1 to 4 show an example of an embodiment of the method for repairing a concrete structure of the present invention. In the present embodiment, as shown in FIG. 1, the method for repairing a concrete structure of the present invention is applied to a partition wall 11 of a reinforced concrete box culvert 10 in which diagonal shear cracks 13 are generated due to shear failure after bending yield. The case where it is done is given as an example.

The method for repairing a concrete structure of the present invention can be applied to a reinforced concrete member in which shear fracture has occurred but axial fracture has not occurred and the internal concrete has not been destroyed. .. In the example shown in FIG. 1, the axial direction of the partition wall 11 is the direction from the ground to the ceiling (that is, the vertical direction), and the axial fracture is the fracture in which the force from above cannot be supported and the partition is crushed.

In the method of repairing a concrete structure of the present embodiment, a through hole 1 is formed through a partition wall 11 which is a member made of reinforced concrete in which shear failure has occurred, and a reinforcing bar 2 is inserted into the through hole 1, and the reinforced concrete is reinforced concrete. A separate plate member 3 and a nut 4 are attached to each of both ends of the reinforcing bar 2 protruding from the partition wall 11 which is a member made of concrete.

Specifically, first, a through hole 1 is formed that penetrates the partition wall 11 in which shear failure has occurred in the thickness direction (in other words, a direction orthogonal to or substantially orthogonal to the surface 11a of the partition wall 11). In other words, the through hole 1 is formed in a direction not parallel to the cracked surface of the sheared crack 13 generated in the partition wall 11 due to shear failure (that is, a direction in which the through hole 1 intersects), and more specifically, in a direction orthogonal to or substantially orthogonal to the cracked surface. Will be done.

Specifically, for example, the through hole 1 is formed by drilling / drilling using a wet diamond core drill.

The through hole 1 is basically provided so as to pass through the shear crack 13 generated in the partition wall 11 due to shear failure. However, considering that the range in which the shear crack 13 is generated in the partition wall 11 may not be clearly specified from the appearance, a part of the through holes 1 are provided without passing through the shear crack 13. It doesn't matter.

When the shear crack 13 reaches the surface 11a (in other words, the wall surface 11a) of the partition wall 11 and appears as the surface crack 13a, the through hole 1 is formed so as to avoid the surface crack 13a. The through hole 1 is also formed so as to avoid the reinforcing bars originally arranged inside the partition wall 11. The positions of the reinforcing bars originally arranged inside the partition wall 11 are confirmed by referring to, for example, a reinforcing bar arrangement diagram at the time of construction and the result of a non-destructive test.

Here, it is preferable that the through hole 1 is formed so as to form a lattice reinforcement after avoiding the surface cracks 13a of the wall surface 11a of the partition wall 11 and the internal reinforcing bars as described above. However, it may be used as a staggered reinforcement. The formation of the through holes 1 is not limited to a specific number, and is appropriately set to an appropriate number after considering the range of shear cracks occurring in the reinforced concrete member to be repaired. Will be done.

The arrangement interval (that is, pitch) along the vertical direction (in other words, the vertical direction) between the plurality of through holes 1 is set to be equal to or less than the thickness D of the partition wall 11 although it is not limited to a specific numerical value. Is preferable. Further, the arrangement interval (pitch) along the horizontal direction (in other words, the lateral direction) of the plurality of through holes 1 is set to be equal to or less than the thickness D of the partition wall 11 although it is not limited to a specific numerical value. Is preferable.

Then, the reinforcing bar 2 is inserted into the through hole 1.

The reinforcing bar 2 functions as reinforcement against shear in the partition wall 11 after shear failure.

The length of the reinforcing bar 2 is adjusted to a dimension larger than the thickness of the partition wall 11 at the position where the shear crack 13 is generated (that is, the thickness of the partition wall 11 including the protrusion due to the occurrence of the shear crack 13). Ru.

As the reinforcing bar 2, a rod-shaped or linear member having screws formed at both ends is used. Specifically, as the reinforcing bar 2, for example, a shredded bolt (also referred to as a long screw bolt or a full screw) can be used.

The diameter of the reinforcing bar 2 is not limited to a specific dimension, but is appropriately set to a value expected to exhibit the strength required for the reinforcing bar. The diameter of the reinforcing bar 2 can be set within a range of about φ10 to 18 mm, specifically, for example, as an example.

Further, the hole diameter of the through hole 1 is not limited to a specific dimension, but is within a range in which the reinforcing bar 2 can be freely inserted and penetrated, that is, although it is slightly larger than the diameter of the reinforcing bar 2. It is preferably set as small as possible. Specifically, for example, the hole diameter of the through hole 1 can be set within the range of about 16 to 24 mm, to give only as an example.

A plate member 3 and a nut 4 are attached to each of both ends of the reinforcing bar 2 inserted into the through hole 1 protruding from each of the facing wall surfaces 11a and 11a of the partition wall 11. That is, the plate member 3 and the nut 4 are attached to the end portion of the reinforcing bar 2 outside the partition wall 11.

The plate member 3 functions as a washer, and a through hole 3b for freely penetrating the reinforcing bar 2 is provided at a central position (in other words, at a central position (in other words, the plate surface 3a)) or a substantially central position in a plan view.

Specifically, as the plate member 3, for example, a rectangular (including a square) or circular steel plate in a plan view in which a through hole 3b is formed is used. The size of the plate member 3 in a plan view (in other words, the size of the plate surface 3a) is not limited to a specific dimension, but the dimension of one side or diameter is set to, for example, about 50 to 250 mm. .. The thickness of the plate member 3 is not limited to a specific dimension, but is set to, for example, about 5 to 30 mm.

A separate plate member 3 is used for each reinforcing bar 2. That is, a common plate member 3 is not attached to the plurality of reinforcing bars 2.

Then, the nuts 4 are tightened at the screw portions at both ends of the reinforcing bar 2 so that the plate surface 3a of the plate member 3 is brought into close contact with the wall surface 11a of the partition wall 11, and the reinforcing bars 2 penetrating the through hole 1 are at both ends. It is screwed with nuts 4 and 4 and fixed to the partition wall 11.

As a result, the shear cracks 13 generated in the partition wall 11 are closed by the pair of plate members 3 and 3 in which the plate surface 3a is brought into close contact with the wall surface 11a of the partition wall 11, and the partition wall 11 is closed in the out-of-plane direction (that is, the partition wall 11). The reinforcing bar 2 is fixed to the partition wall 11 while restraining the protrusion in the direction orthogonal to the wall surface 11a.

Here, it is conceivable that due to the out-of-plane protrusion of the partition wall 11 due to the occurrence of the shear crack 13, there may be a portion where the facing wall surfaces 11a and 11a of the partition wall 11 are not parallel to each other. When the reinforcing bar 2 penetrating the partition wall 11 is provided at the portion where the facing wall surfaces 11a and 11a are not parallel to each other, it is conceivable that the plate surface 3a of the plate member 3 is not parallel to the wall surface 11a.

When the wall surface 11a of the partition wall 11 and the plate surface 3a of the plate member 3 are not parallel to each other due to the out-of-plane protrusion of the partition wall 11 due to the occurrence of the shear crack 13, the wall surface is as shown in FIG. An inclined washer 5 (also referred to as a "taper washer") is used to fill the gap between the 11a and the plate surface 3a.

Specifically, for example, the inclined washer 5 has a shape aligned with the plate member 3 in a plan view and has a through hole 5a for penetrating the reinforcing bar 2, and also has a back surface (that is, a wall surface 11a of the partition wall 11). It is formed of steel as if the surface on the side that comes into contact with it is inclined.

As the method of using the inclined washer 5, for example, the following 1) and 2) can be considered.

1) An inclined washer is used at one end of both ends protruding from each of the walls 11a and 11a that are not parallel to each other, while an inclined washer is not used at the other end.
In this case, the reinforcing bar 2 is orthogonal to one of the wall surfaces 11a and 11a that are not parallel to each other due to the occurrence of shear cracks 13 and is inclined with respect to the other wall surface 11a. Is arranged.

2) Inclined washers are used at both ends protruding from each of the walls 11a and 11a that are not parallel to each other.
In this case, the reinforcing bars 2 are arranged along an arbitrary direction with respect to each of the wall surfaces 11a and 11a regardless of the inclination of the wall surfaces 11a and 11a which are not parallel to each other due to the occurrence of the shear crack 13. obtain.

In addition, by using the inclined washer 5, the reinforcing bar 2 is in the axial direction (that is, the direction from the ground to the ceiling) in the sound state of the partition wall 11 regardless of the inclination of the facing wall surfaces 11a and 11a. That is, the aspect arranged along the direction orthogonal to the vertical direction (that is, the horizontal direction) and the direction orthogonal to one of the facing wall surfaces 11a and 11a (and the other). A mode in which the wall surface is arranged along the direction of inclination) can be appropriately selected.

It is preferable that the nut 4 is tightened so as to restrain the expansion of the gap generated as the shear crack 13 by using, for example, a torque wrench, and further, to close the shear crack 13 as much as possible. In order to prevent loosening of the nut tightening, it is preferable that nuts are attached to both ends of the reinforcing bar 2 in double to form a double nut.

According to the method for repairing a concrete structure configured as described above, a separate plate member 3 is attached to each of both ends of the reinforcing bar 2 for each reinforcing bar 2, and the concrete structure is made of reinforced concrete. Since the partition wall 11 which is a member of the above is not surrounded by a steel plate, it can be applied to surface members such as various walls made of reinforced concrete and wall-type structures. Therefore, it is possible to repair a member to which a method of surrounding the circumference with a steel plate cannot be applied.

According to the repair method of the concrete structure configured as described above, it was confirmed by the inventor that the yield strength of the member is restored when it is applied to the member made of reinforced concrete in which shear failure has occurred. This is a method, and it is possible to repair a member made of reinforced concrete that has been shear-broken while appropriately reinforcing it by post-construction.

Although the above-described embodiment is an example of a preferred embodiment of the present invention, the embodiment of the present invention is not limited to the above-mentioned embodiment, and the present invention is not limited to the above-mentioned embodiment and does not deviate from the gist of the present invention. The invention can be modified in various ways.

For example, in the above-described embodiment, the case where the concrete structure to which the present invention is applied is the box culvert 10 shown in FIG. 1 and the member made of reinforced concrete is the partition wall 11 of the box culvert 10 is taken as an example. The concrete structure and the member made of reinforced concrete to which the present invention is applied are not limited to the example shown in FIG. 1, and are not limited to the box culvert and its partition wall in the first place, and various structures made of reinforced concrete. The present invention can be applied to various members constituting the above. In particular, the present invention can be applied to a surface member or a wall-type structure among the members constituting a structure made of reinforced concrete.

An example of verifying the effect of repairing / restoring a member made of reinforced concrete in which shear failure has occurred by the method for repairing a concrete structure of the present invention will be described with reference to FIGS. 5 to 7.

In this example, the reinforced concrete box culverts shown in FIGS. 5A and 5B were used as test bodies. In addition, this test piece was placed in two steps with a seam provided at a position 100 mm above the lower haunch. In addition, no shear reinforcement was placed in the test section.

First, static horizontal loading was performed on the test piece as a primary loading until a decrease in horizontal bearing capacity was clearly observed on the load displacement curve. Specifically, the applied force was a repeated gradual loading that pushed and pulled the top plate with two 500 kN actuators. The control was displacement control based on the interlayer deformation angle, and the basic pattern was to make three rounds at each turning point. After loading three laps at each turning point, it was judged that the horizontal bearing capacity had sufficiently decreased when ± 3% was loaded two laps, and the load was pushed to the positive side (note that the interlayer deformation angle was 5.6%). there were).

Next, as a secondary load, a post-construction shear reinforcement as a method of repairing the concrete structure of the present invention for a vertical member (that is, a side wall that divides the road space of a box calvert) that was shear-broken after bending and yielding in the primary load. The recovery of mechanical performance was verified.

A shredded bolt with a diameter of 14 mm was used as a reinforcing bar. The tightening force per shredded bolt is controlled by a strain gauge attached to the reinforcing bar, and is 100 MPa (ε≈), which is 0.25 times the 0.2% yield strength of the shredded bolt used as the reinforcing bar. 500 μ).

After the construction was completed, it was confirmed that the crack width was reduced by the tightening force of the reinforcing bar, and the amount of protrusion of the member in the out-of-plane direction was also reduced.

The secondary load was started from the negative side where the residual proof stress was lower than the positive side in the primary load, and the load was positive and negative up to the stroke limit of the actuator.

The secondary loading gave the results shown in FIG. 6 as the relationship between horizontal displacement and horizontal load. From the results shown in FIG. 6, the maximum proof stress is 307 kN developed in the cycle of the first round of the negative side, which is the negative residual proof stress of the primary load (the maximum proof stress is 4.5% between the interlayer deformation angles). It was confirmed that it was 1.88 times that of (273 kN at that time). On the other hand, it was confirmed that the load on the first lap on the positive side was less than the residual load capacity of the primary load. The maximum proof stress on the second lap on the negative side was 209 kN, which was 68% of the maximum proof stress on the first lap on the negative side, but it was confirmed that it exceeded the residual proof stress on the negative side of the primary load.

Due to the secondary loading, the results shown in FIG. 7 were obtained as the strain of the reinforcing bar constructed after the peak of the first round on the negative side. From the results shown in FIG. 7, it was confirmed that the strains of the uppermost reinforcing bars in the plastic hinge section and penetrating the diagonal cracks were all less than the strain of 500 μm at the time when the tightening force was introduced. From this, it was considered that the reinforcing bars installed in the plastic hinge section did not contribute significantly to the increase in yield strength. Although the strain of the reinforcing bars at the positions penetrating the split cracks in the second and third steps from the bottom varied even in the same step, some reinforcing bars were close to the yield strain and tended to exceed the strain of the top reinforcing bars. Was confirmed. As a result, although the strain of the reinforcing bars was biased in the height direction of the test piece, the horizontal bearing capacity was restored by the restoration measures by the repair method of the concrete structure of the present invention even in the state where the horizontal bearing capacity was greatly reduced by the primary loading. It was confirmed that it was done.

In addition, the appearance of the test piece after the completion of reinforcement construction after the primary loading was compared with the appearance of the test piece at the peak on the negative side of the first round, and the crack width of the diagonal crack extending from the upper right to the lower left of the upper south side wall was compared. Although widening was observed, it was confirmed that no new noticeable damage had occurred. This is because the reinforcing bar whose end is fixed by the plate member and the nut restrains the member from protruding in the out-of-plane direction, and the ratio of bending deformation and rotational deformation due to the extension of the reinforcing bar to the total deformation amount. It was thought that it was due to the increase in height.

From the above results, the effect of the repair method of the concrete structure of the present invention for repairing and restoring the surface member made of reinforced concrete in which shear failure occurred after bending yield was verified, and the strain of the reinforcing bar constructed afterwards was high. It was confirmed that the horizontal strength is restored by the repair method of the present invention even when the horizontal strength is greatly reduced, although the bias is observed. As a result, it was confirmed that the present invention is effective and useful as a method for repairing a member made of reinforced concrete that has been shear-broken while reinforcing it by post-construction.

Other verification examples of the effect of repairing / restoring the reinforced concrete member in which shear failure has occurred by the method for repairing a concrete structure of the present invention will be described with reference to FIGS. 8 to 13.

In this embodiment, a beam member made of reinforced concrete that has been shear-broken is used as a member for verification, and all the test pieces are designed to be shear-broken based on the standard material strength.

Specifically, the shear force-curvature relationship of the test piece was obtained, and it was designed to reach the shear strength before reaching the bending yield point on this curve. The shear force-curvature relationship was obtained from cross-sectional analysis using the plane holding assumption and the ACI stress block as the three bend lines passing through the origin, bending crack point, and bending yield point. The shear strength of the test piece is the deep beam type of two birds (Junichiro Niwa et al .: Proposal on the design method of RC beam members like deep beam, Proceedings of the 5th Annual Lecture Meeting on Concrete Engineering, pp.357- 360, 1983) and modified Okamura Hikai formula (Junichiro Futaba et al .: Re-evaluation of the shear strength formula of RC beams without shear reinforcement, JSCE Proceedings, No. 372 / V-5, pp. 167- 176, 1986) was used to calculate. The reduction of shear strength after bending yield is described by Noguchi et al.'S shear deterioration coefficient ξ (Satoshi Noguchi et al .: Seismic damage analysis considering shear deterioration of concrete in railway rigid frame bridges, Structural Engineering Proceedings, Vol. 54A, 2008). Used and sought after.

The overall view and the cross-sectional view of the beam of the test piece used in this example are shown in FIGS. 8 and 9. The cross section of the beam member was 180 mm × 250 mm, and a threaded reinforcing bar was used for the tensile reinforcing bar.

The test section was a one-sided span (that is, the right side when facing the drawings of FIGS. 8 and 9) in which the shear reinforcing bars were not arranged.

The experimental parameter is the fracture mode of the specimen set by adjusting the shear span ratio and the reinforcing bar ratio. Specifically, the test piece shown in FIG. 8 has a design failure mode of shear compression failure, and the test piece shown in FIG. 9 has a design failure mode of diagonal tensile failure.

The set values of each test piece are as shown in Table 1 below.

In the present invention, as a concept of restoration measures for a concrete member that has been shear-broken, the shear strength of the member subjected to the restoration method exceeds the bending strength at the time of designing the test piece, and the bending type load having abundant toughness when the load is applied again. -I intend to draw a displacement curve.

As a configuration related to the application of the present invention in the present embodiment, the diameter of the through hole (in other words, the drilled hole) is set to φ20 mm, and the reinforcing bar (specifically, the PC steel rod of class C No. 1 is used. The diameter was set to φ13 mm, and standard products for φ13 mm PC steel rods were used for the plate members (in other words, the bearing plate), washers, and nuts. The through hole that was drilled was not backfilled.

As a configuration related to the application of the present invention in the present embodiment, a torque wrench is used for the PC steel rod as a reinforcing bar, and a tightening force is introduced in the beam direction of the damaged member so as to close the crack. Was done. The tightening force per PC steel rod was controlled by a strain gauge attached to the PC steel rod, and the target was about 13 kN (corresponding to 500 μ).

The restoration measures / restoration method as an application of the present invention was carried out at the stage when a clear decrease in the proof stress of the test body DT1 and the test body SC1 was confirmed in the primary loading. At this time, the restoration measures were taken by applying the restoration method while the displacement due to the primary loading remained.

Specifically, the loading was performed as a three-point bending loading using one 1000 kN jack at the center position of the span. The load was controlled by controlling the displacement.

For the test body DT1 and the test body SC1 as application examples of the present invention, the primary loading is performed until a clear decrease in proof stress can be confirmed in the test body, and the secondary loading after the restoration measures is pushed out until the decrease in proof stress can be confirmed. Was done with the goal.

As for the test body DT2 and the test body SC2 as comparative examples, in order to confirm the mechanical performance of the test body until the end of the test body, recovery measures are not taken, and the goal is to push through until a clear decrease in yield strength is observed. Was loaded.

Loading was performed on each test piece, and the results shown in FIGS. 10 to 13 were obtained as the load-displacement relationship for each test piece. The dotted line in each figure is the ultimate bending strength obtained from the cross-sectional analysis, and the alternate long and short dash line is the maximum strength obtained from the above-mentioned shear strength evaluation formula. In each figure, the △ mark is the point where the lower end bar is tensile yielded, the ○ mark is the point showing the maximum yield strength, and the ◆ mark is the point where the crushing of the concrete is clearly confirmed.

The results shown in Table 2 were obtained as a result of the primary loading, and the results shown in Table 3 were obtained as a result of the secondary loading.

As a result of the primary loading, the test piece DT2 suffered a shear crack during loading from a displacement of 3.0 mm to 3.5 mm, and its yield strength suddenly decreased. The fracture mode was determined to be diagonal tensile fracture.

Although the test piece SC2 had shear cracks during loading from the displacement of 0.85 mm to 0.90 mm, the proof stress continued to increase and reached the maximum proof stress at the displacement of 2.5 mm. Immediately after reaching the maximum yield strength, the yield strength dropped significantly. The fracture mode was determined to be shear compression fracture.

As a result of the primary loading, and in the test piece DT1, shear cracks occurred during loading from the displacement of 3.0 mm to 3.5 mm, and the yield strength suddenly decreased. The fracture mode was determined to be diagonal tensile fracture.

Although the test piece SC1 had shear cracks during loading from the displacement of 0.80 mm to 0.85 mm, the proof stress continued to increase and reached the maximum proof stress at the displacement of 1.9 mm. Immediately after reaching the maximum yield strength, the yield strength began to drop significantly. The fracture mode was determined to be shear compression fracture.

As a result of the secondary loading, the lower end muscle of the test piece DT1 yielded in tension during the loading from the displacement of 6.5 mm to 7.0 mm. After that, the maximum yield strength was exhibited at the point where the displacement was 9.3 mm, and after that, crushing of the concrete was confirmed near the loading point as the loading proceeded. The rupture mode of the secondary load was determined to be bending rupture.

In the test piece SC1, the lower end streaks yielded tensilely at a displacement of 3.0 mm, and the maximum yield strength was reached at a displacement of 7.5 mm. Since the yield strength decreased with the progress of crushing of concrete near the loading point, it was judged that the fracture mode of the secondary loading was bending fracture.

As described above, in the secondary loading of the test body DT1 and the test body SC1 judged to have undergone shear failure in the primary loading, the lower end streaks yielded, and the yield strength exceeding the ultimate bending strength at the design stage was exhibited. From this, it was confirmed that the shear strength exceeded the bending strength at the design stage and the fracture mode shifted from the shear fracture of the primary load to the bending fracture by applying the restoration measures according to the present invention.

A loading experiment was conducted to verify the recovery of mechanical performance / structural performance by constructing a restoration method using a PC steel rod as an application of the present invention to a reinforced concrete beam that has been shear-broken. Based on the above results, the present invention relates to the present invention. According to the method of repairing concrete structures, even for reinforced concrete beams that have already undergone shear failure, the shear strength exceeds the shear strength at the time of bending strength after restoration measures, and the failure mode is shifted to bending fracture. Was confirmed to be possible. As a result, it was confirmed that the present invention is effective and useful as a method for repairing a member made of reinforced concrete that has been shear-broken while reinforcing it by post-construction.

1 Through hole 2 Reinforcing bar 3 Plate member 3a Plate surface 4 Nut 10 Box culvert 11 Partition 11a Partition surface / wall surface 13 Shear crack 13a Surface crack

Claims (3)

A through hole is formed through the reinforced concrete member in which shear failure has occurred, and a reinforcing bar is inserted into the through hole, and the reinforcing bar is inserted into each of both ends of the reinforcing bar protruding from the reinforced concrete member. Separate plate members and nuts are attached to each , and
A method for repairing a concrete structure, characterized in that an inclined washer is further arranged between the reinforced concrete member and the plate member. The method for repairing a concrete structure according to claim 1, wherein at least a part of the through holes is provided so as to pass through a shear crack generated in the reinforced concrete member due to the shear failure. The concrete structure according to claim 1 or 2, wherein when a plurality of the through holes are formed, the arrangement interval between the through holes along the vertical direction is equal to or less than the thickness of the reinforced concrete member. Repair method.

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