JP2012031608A - Strengthening performance improvement method and strengthening performance improvement structure for floor slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strengthening performance improvement method and a strengthening performance improvement structure for a floor slab capable of improving shear capacity so as not to cause a shear fracture before the occurence of flexural fracture, so that a flexural reinforcement effect is exhibited and a flexural strength can be improved.SOLUTION: A floor slab 1 is provided with a floor slab body 10, a thickening portion 20 provided below the floor slab body 10, and a reinforcement material 30. The plurality of reinforcement materials 30 are nearly vertically provided from the lower end surface of the thickening portion 20 to immediately below a floor slab upper reinforcement 13. Each of the reinforcement materials 30 is provided in a hole 16 formed in the floor slab body 10 and the thickening portion 20 and the circumference thereof is covered with a quick-curing filler 17. Because the quick-curing filler 17 is in close contact with the circumference of the reinforcement material 30, the reinforcement material 30 is firmly fixed to the floor slab body 10 and the thickening portion 20.

Description

  The present invention relates to a method for improving a reinforcing performance of a floor slab and a reinforcing performance improving structure.

  The bridge slab of the road bridge is subjected to repeated bending load from the automobile passing through the upper part, so reinforcement may be required, such as a crack on the lower surface of the concrete. When reinforcing such a floor slab, it is desirable not to obstruct the passage of the automobile on the floor slab. Therefore, conventionally, as described in the prior art column of Patent Document 1, a steel plate is disposed along the lower surface of the floor slab, and the method of fixing the steel plate with an anchor and an adhesive, A method of attaching high-strength fibers such as carbon fibers to the lower surface with an adhesive is used.

JP 2002-167777 A

  However, the applicants of the present application conducted a loading test on the floor slab reinforced by the reinforcing method described in Patent Document 1 and analyzed the loading test. As a result, although the bending strength was improved, the shear strength was It has not been improved so much, and it has been found that shear fracture may occur before bending fracture. Note that the loading test and analysis by which the applicants of the present application have obtained this knowledge will be described in the section of the embodiment for carrying out the invention.

  Therefore, the present invention has been made in view of the above-described problems, and improves the bending strength by improving the shear strength and not causing the shear failure before the bending failure occurs, thereby improving the bending strength. An object of the present invention is to provide a method for improving the reinforcement performance of a floor slab and a structure for improving the reinforcement performance.

The present invention is a method for improving the reinforcing performance of a floor slab in which reinforcing bars are embedded in the vicinity of the upper surface and the vicinity of the lower surface,
A reinforcing material having a length capable of obtaining a shear reinforcement effect is provided in the floor slab from the upper surface side or the lower surface side of the floor slab to the opposite surface.
According to the present invention, the shear strength can be improved by installing a reinforcing material having a length capable of obtaining a shear reinforcement effect in the floor slab. Therefore, when a bending load is applied to the floor slab, it is difficult for shear fracture to occur, so that the bending strength can be improved.

  Moreover, in this invention, it is good also as installing the said reinforcing material so that the front-end | tip may reach the reinforcing bar vicinity of the said opposite surface.

  Moreover, in this invention, after forming a hole in the upper surface or lower surface of the said floor slab, and filling the said hole with a quick-hardening filler, it is good also as inserting the said reinforcing material in the said hole.

  In the present invention, the reinforcing material may be driven from the upper surface or the lower surface.

The present invention is a reinforcing performance improving structure of a floor slab in which reinforcing bars are embedded near the upper surface and the lower surface,
The floor slab is provided with a reinforcing material having a length that is installed from the upper surface side or the lower surface side of the floor slab toward the opposite surface and that can obtain the effect of shear reinforcement.

  Moreover, in this invention, the said reinforcing material is good also as being installed so that the front-end | tip may reach the reinforcing bar vicinity of the said opposite surface.

  Moreover, in this invention, the said reinforcing material is installed in the hole formed in the said floor slab, It is good also as the circumference | surroundings being filled with the quick-hardening filler.

  According to the present invention, there is provided a method for improving the reinforcing performance of a slab capable of improving the bending strength and improving the bending strength by improving the shear strength and not causing the shear fracture before the bending fracture occurs. A reinforcing performance improving structure can be provided.

It is a vertical sectional view showing the reinforcing structure of the floor slab of the road bridge according to the present embodiment. It is the figure which expanded the reinforcement material vicinity of a floor slab. It is a figure which shows the site | part, member, etc. which comprise each test body which simulated the road bridge RC floor slab. 3 is a side sectional view of a test body 42. FIG. 3 is a side sectional view of a test body 43. FIG. 3 is a side sectional view of a test body 44. FIG. 4 is a side sectional view of a test body 45. FIG. It is a figure which shows the analysis model of each test body. It is a figure which shows the analysis conditions of each test body. It is a figure which shows the loading state of each test body. It is a figure which shows the relationship between the load and displacement which were loaded on each test body. It is a figure which shows the bending strength of each test body 42-45, the shear strength, and the analytical value of a maximum load, and the test result of a loading test. It is a figure which shows the other Example of the length of a reinforcing material. It is a figure which shows the state which installed the reinforcing material from the lower end surface of a floor slab.

  Hereinafter, an example in which an embodiment of a reinforcing performance improving method and a reinforcing performance improving structure of a floor slab according to the present invention is applied to a road bridge RC floor slab will be described in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing a reinforcing structure 2 of a floor slab 1 of a road bridge according to this embodiment. FIG. 2 is an enlarged view of the vicinity of the reinforcing material 30 of the floor slab 1.
As shown in both figures, a floor slab 1 of a road bridge includes a floor slab body 10, a thickened portion 20 provided under the floor slab body 10, and a reinforcing member 30, and is a pair of H-shaped steel. The spar 3 is supported.

  The floor slab main body 10 is composed of a plate-shaped ordinary concrete portion 12, a floor slab upper rebar 13, a floor slab lower rebar 14, and a distribution bar 15.

  The floor slab upper reinforcing bar 13 and the distributing bar 15 and the floor slab lower reinforcing bar 14 and the distributing bar 15 are arranged in a lattice pattern in plan view in the vicinity of the upper surface and the lower surface of the ordinary concrete portion 12, respectively.

The thickened portion 20 includes a sprayed concrete portion 21 and a reinforcing reinforcing bar 22.
The shotcrete portion 21 is made of polymer cement mortar having higher durability than ordinary concrete.
The reinforcing reinforcing bars 22 are arranged in a lattice shape in a plan view at a position having an appropriate covering in the shot concrete part 21.

  A plurality of reinforcing members 30 are installed substantially vertically from the lower end surface of the shotcrete part 21 to just below the floor slab upper rebar 13. In the present embodiment, hexagonal bolts are used as the reinforcing member 30, but the present invention is not limited to this. May be used.

  The reinforcing material 30 passes through the thickened portion 20 and is installed in the hole 16 formed in the floor slab body 10, and the periphery is covered with the fast-hardening filler 17. Since the quick-hardening filler 17 is in close contact with the periphery of the reinforcing material 30, the reinforcing material 30 is firmly fixed to the floor slab body 10 and the thickened portion 20, and is difficult to come off.

The hole 16 for installing the reinforcing member 30 is formed by drilling upward from the lower side of the floor slab 1.
The hole 16 is formed between these reinforcing bars so as not to damage the floor slab upper reinforcing bar 13, the floor slab lower reinforcing bar 14, the distribution reinforcing bar 15, and the reinforcing reinforcing bar 22. Therefore, the position of the hole 16 is appropriately determined depending on the positions of the existing reinforcing bars 13, 14, 15, and 22.

  In addition, as the number of reinforcing members 30 to be installed increases, the shear strength increases. Is determined.

  The reinforcing material 30 is inserted into the fast-hardening filler 17 after filling the hole 16 with the quick-hardening filler 17. In the present embodiment, an epoxy resin is used as the fast-curing filler 17, but the present invention is not limited to this, and other resin systems, cement systems, and the like may be used. In short, any material may be used as long as it has fluidity at the time of construction and cures to exhibit a predetermined strength after a predetermined time.

  As described above, the configuration in which the reinforcing member 30 is installed substantially vertically from the lower end surface of the sprayed concrete portion 21 to the floor slab upper rebar 13 of the floor slab body 10 can improve the shear strength of the floor slab 1. This was confirmed by a loading test and an analysis of this loading test. The loading test and analysis method will be described below.

--- About loading test and analysis ---
FIG. 3 is a diagram showing the parts, members, and the like constituting each test body 42 simulating the floor slab 1.
As shown in this figure, a plurality of test bodies 42 to 45 having different lengths and numbers of the reinforcing members 30 are produced, and a loading test is performed on each of the test bodies 42 to 45, and an analysis of the loading test is performed. It was.
In the loading test and analysis, anchor bolts 31 and 32 were used as the reinforcing material 30. Although details will be described later, the anchor bolt 31 installed in the vicinity of the floor slab lower rebar 14 from the lower end surface of the thickened portion 41 is displayed as “short” in FIG. The anchor bolt 32 installed just below the reinforcing bar 13 is indicated as “long” in FIG. 3.
In addition, the test bodies 42 and 43 are the test bodies used for the loading test and analysis described in the column of the problem to be solved by the invention, and are described for comparison.

  Next, each test body 42 to 45 will be described in detail.

FIG. 4 is a side sectional view of the test body 42.
As shown in the figure, the test body 42 is composed only of the floor slab body 10. The floor slab body 10 includes a normal concrete portion 12 having a predetermined strength, a floor slab upper rebar 13 and a floor slab lower rebar 14 embedded in a lattice pattern in the vicinity of the upper and lower surfaces of the normal concrete portion 12, Near the lower surface, there is provided a distribution bar 15 embedded so as to be orthogonal to the floor slab upper rebar 13 or the floor slab lower rebar 14.

FIG. 5 is a side sectional view of the test body 43.
As shown in the figure, the test body 43 is composed of a floor slab body 10, a thickened portion 41, and anchor bolts 31.
The thickened portion 41 includes a reinforcing reinforcing bar 22 placed on the lower surface of the floor slab body 10 and a sprayed concrete portion 21 sprayed so as to cover the reinforcing reinforcing bar 22.
The anchor bolt 31 is driven from the lower side of the thickened portion 41 toward the upper side, passes through the lower end surface of the thickened portion 41 and is installed substantially vertically up to the vicinity of the floor slab lower rebar 14. The anchor bolt 31 is used as a fixing means for fixing the reinforcing steel bar 22 and the sprayed concrete portion 21 to the floor slab body 10. In this embodiment, the anchor bolts 31 are installed in four rows in the left-right direction in FIG.

FIG. 6 is a side sectional view of the test body 44.
As shown in the figure, the test body 44 includes the floor slab body 10, the thickened portion 20, and the anchor bolt 32.
The thickened portion 20 includes a shotcrete portion 21 and a reinforcing reinforcing bar 22 installed in the shotcrete portion 21.
The reinforcing steel bar 22 is embedded at a position 5 mm below the upper surface of the thickened portion 20.
The anchor bolts 32 are arranged so as to form four rows substantially vertically from the vicinity of the lower end surface of the thickened portion 20 to immediately below the floor slab upper rebar 13.
The anchor bolt 32 is installed in the hole 16, and the periphery is covered with the fast-hardening filler 17.

FIG. 7 is a side sectional view of the test body 45.
As shown in this figure, the test body 45 is obtained by increasing the anchor bolts 32 of the test body 44 in seven rows.

A loading test in which a load was loaded at two positions symmetrical about the central axis of each of the test bodies 42 to 45 having the above-described configuration was analyzed by a two-dimensional finite element method. The analysis model and analysis conditions at this time are shown in FIGS. 8 and 9, respectively. Moreover, the bending proof stress of each test body 42-45, the shearing proof strength, the analysis result of a maximum load, and the test result (it mentions later for details) of a loading test are shown in FIG. In addition, the load of each test body 42-45 described in FIG. 12 is made dimensionless by setting the actual measurement value of the maximum load of the loading test result of the test body 42 to 1.00.
As described above, the test body 43 and the test bodies 44 and 45 have a great influence on the results of the loading test and analysis, although the installation positions of the reinforcing reinforcing bars 22 and the lower end positions of the anchor bolts 31 and 32 are different. The results obtained from the loading test and analysis were directly compared.

<About bending strength>
As shown in FIG. 12, the bending strength prediction values of the test bodies 42 to 45 are 1.03, 1.60, 1.60, and 1.60, respectively, and the bending strength prediction values of the test bodies 43 to 45 are all. It became the same value.
From these results, it is considered that the bending strength is greatly improved by providing the thickened portion 41 and the anchor bolts 31 and 32. Moreover, it is thought that the influence on bending strength by the difference in the length and number of anchor bolts 31 and 32 is small.
<About shear strength>
The predicted shear strength values of the test bodies 42 to 45 were 0.88, 1.13, 1.37, and 1.67, respectively.
First, when the results of the test body 42 and the test body 43 are compared, it is considered that the shear strength is improved by providing the thickened portion 41.
Moreover, when the results of the test body 43 and the test body 44 are compared, it is considered that the shear strength is improved as the anchor bolts 31 and 32 become longer.
Furthermore, when the results of the test body 44 and the test body 45 are compared, it is considered that the shear strength is improved by increasing the anchor bolt 32.
<About maximum load>
The maximum load values of the test bodies 42 to 45 were 0.95, 1.13, 1.32 and 1.59, respectively.
Here, the maximum load values of the test bodies 43 and 44 are substantially the same as the respective shear strength prediction values. On the other hand, the maximum load value of the test body 45 is almost the same value as the predicted bending strength.
First, when the results of the test body 42 and the test body 43 are compared, it is considered that the maximum load is improved by providing the thickened portion 41.
Further, when the results of the test body 43 and the test body 44 are compared, it is considered that the maximum load is improved as the anchor bolts 31 and 32 become longer.
Furthermore, when the results of the test body 44 and the test body 45 are compared, it is considered that the maximum load is improved by increasing the anchor bolt 32.
And since the maximum load value of the test bodies 43 and 44 is a value substantially the same as each shear strength prediction value, it is thought that the test bodies 43 and 44 produce a shear failure in a loading test. On the other hand, since the maximum load value of the test body 45 is substantially the same value as the predicted bending strength value, it is considered that the test body 45 is subjected to bending failure in the loading test.

  In parallel with the analysis, as shown in FIG. 10, a load was actually loaded on each of the test bodies 42 to 45, and the maximum load value was measured.

FIG. 11 is a diagram showing the relationship between the load loaded on each of the test bodies 42 to 45 and the displacement. In addition, the displacement of each test body 42-45 described in FIG. 11 is made dimensionless by setting the displacement at the time of the maximum load value of the loading test result in the test body 42 to 1.00. As in FIG. 12, the actual measurement value of the maximum load of the loading test result of the test body 42 is set to 1.00 and is made dimensionless.
<About Specimens 42 and 43>
As shown in FIG. 11, the load-displacement curves of both test bodies 42 and 43 both show a form due to shear fracture that suddenly drops to the right after receiving the maximum load.
Furthermore, as shown in FIG. 12, the actual measured values 1.00 and 1.08 of the maximum loads of the test bodies 42 and 43 substantially coincide with the predicted shear strength values 0.88 and 1.13, respectively.
From these results, it can be seen that both specimens 42 and 43 were brought into a final state by shear fracture. Moreover, although the test body 43 improved the bending proof strength compared with the test body 42, the shear proof strength did not improve so much, and it is thought that the shear rupture occurred before the bending rupture.
Therefore, as described in the column of the problem to be solved by the invention, it is understood that in order for the test body 43 to obtain the effect of bending reinforcement by the thickened portion 20, it is necessary to improve the shear strength.
<About Specimen 44>
As shown in FIG. 11, the load-displacement curve of the test body 44 shows a form due to shear fracture that suddenly falls to the right after receiving the maximum load.
Further, as shown in FIG. 12, the actual measurement value 1.22 of the maximum load of the test body 44 substantially coincides with the predicted shear strength value 1.37.
From these results, it can be seen that the specimen 44 was brought into a final state by shear fracture. Moreover, although the test body 44 has the shear strength improved more than the test body 43 by installing the long anchor bolt 32, in order for the test body 44 to obtain the effect of bending reinforcement by the thickened portion 20, It can also be seen that it is necessary to improve the shear strength.
<About Specimen 45>
As shown in FIG. 11, the load-displacement curve of the test body 45 decreases to the right after receiving the maximum load, but increases again, and then gradually decreases to the right.
Furthermore, as shown in FIG. 12, the actual measurement value 1.68 of the maximum load of the test body 45 is almost the same value as both the bending strength prediction value 1.60 and the shear strength prediction value 1.67. .
From these results, it is considered that in the test body 45, shear fracture and bending fracture occurred almost simultaneously. Therefore, it can be seen that the test body 45 sufficiently obtained the effect of bending reinforcement by the thickened portion 20 due to the improved shear strength.

From the results of the analysis and loading test described above, by installing the anchor bolt 32 from the lower end surface of the thickened portion 20 to the vicinity of the floor slab upper rebar 13, the floor slab lower rebar 14 from the lower end surface of the conventional thickened portion 20 is installed. It can be seen that the shear strength is improved as compared with the case where it is installed up to the vicinity.
It can also be seen that the shear strength is further improved by increasing the number of anchor bolts 32.

<Summary>
As can be seen from the results of the above analysis and loading test, in the floor slab 1 according to the present embodiment, the reinforcing material 30 is installed from the lower end surface of the thickened portion 20 to the vicinity of the floor slab upper rebar 13 of the floor slab body 10. As a result, the shear strength can be improved. Conventionally, even if the thickened portion 20 is provided on the floor slab 1, only the bending strength is improved, and the improvement of the shear strength is small. Therefore, the shear failure is caused by the loading load much smaller than the bending strength. In the embodiment, by installing the reinforcing material 30 up to the vicinity of the floor slab upper rebar 13, the shear strength is greatly improved, and when a bending load is applied to the floor slab 1, it is difficult for shear fracture to occur. Can be improved.

  In the present embodiment, the reinforcing member 30 is installed from the lower surface of the thickened portion 20 to the vicinity of the floor slab upper rebar 13, but is not limited to this length, and obtains a desired shear strength. For example, as shown in FIG. 13 (a), the upper end exists near the center of the ordinary concrete portion 12, or as shown in FIG. Alternatively, as shown in FIG. 13 (c), the ordinary concrete portion 12 may be penetrated and a nut 33 may be fixed to the tip thereof. The point is that the floor slab 1 may be of a length that can have a desired shear strength determined in advance by design or the like.

  In the present embodiment, the case where the hole 16 is formed in the floor slab 1 and the thickened portion 20 and the reinforcing member 30 is inserted into the hole 16 has been described. However, the present invention is not limited to this method. You may drive and install in the lower surface of the thick part 20. FIG. In such a case, the time for installing the reinforcing member 30 can be greatly shortened.

  In addition, in this embodiment, although the case where the reinforcing material 30 was installed in the floor slab 1 provided with the thickening part 20 was demonstrated, it is applicable also when only the floor slab 1 is provided. Specifically, as shown in FIG. 14, the reinforcing member 30 may be installed substantially vertically from the lower end surface of the floor slab 1 to the vicinity of the floor slab upper rebar 13.

  In addition, in this embodiment, although the application example to the existing floor slab 1 was demonstrated, it is not limited to this, and it cannot be overemphasized that it can apply also to the floor slab 1 at the time of new installation. In such a case, the reinforcing material 30 may be installed when the floor slab upper reinforcing bars 13 and the distribution bars 15 are installed.

DESCRIPTION OF SYMBOLS 1 Floor slab 2 Reinforcement structure 3 Girder material 10 Floor slab main body 12 Normal concrete part 13 Floor slab upper rebar 14 Floor slab lower rebar 15 Distribution bar 16 Hole 17 Fast-hardening filler 20 Thickening part 21 Sprayed concrete part 22 Reinforcement reinforcing bar 30 Reinforcing material 31 Anchor bolt (short)
32 Anchor bolt (long)
33 Nut 41 Thickened part 42 Test body 43 Test body 44 Test body 45 Test body

Claims (7)

A method for improving the reinforcing performance of a floor slab in which reinforcing bars are embedded near the upper surface and the lower surface,
A method for improving the reinforcing performance of a floor slab, comprising installing in the floor slab a reinforcing material having a length capable of obtaining a shear reinforcement effect from an upper surface side or a lower surface side of the floor slab to an opposite surface.   2. The method for improving the reinforcing performance of a floor slab according to claim 1, wherein the reinforcing material is installed so that the tip thereof reaches the vicinity of the reinforcing bar on the opposite surface.   The floor slab according to claim 1 or 2, wherein a hole is formed on an upper surface or a lower surface of the floor slab, and the reinforcing material is inserted into the hole after the hole is filled with a fast-hardening filler. Reinforcement performance improvement method.   3. The method for improving the reinforcing performance of a floor slab according to claim 1, wherein the reinforcing material is driven from the upper surface or the lower surface. Reinforcement performance improvement structure of the floor slab with reinforcing bars embedded near the upper surface and the lower surface,
The floor slab is provided with a reinforcing material having a length that is installed from the upper surface side or the lower surface side to the opposite surface of the floor slab to obtain a shear reinforcement effect. Construction.   6. The reinforcing structure for reinforcing a floor slab according to claim 5, wherein the reinforcing material is installed so that a tip of the reinforcing material reaches a vicinity of a reinforcing bar on the opposite surface.   The reinforcing performance of the floor slab according to claim 5 or 6, wherein the reinforcing material is installed in a hole formed in the floor slab, and the periphery thereof is filled with a fast-hardening filler. Improved structure.

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