JP2003138521A - Re placing method for slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely easily replace a slab constituting a road bridge without causing buckling in a girder. SOLUTION: A girder reinforcing mechanism 11 is installed in a middle girder part 5. A tendon 14 composed of a steel bar 14a of the girder reinforcing mechanism 11 is tensioned to some extent by a length adjustment mechanism 41, a jack 23 of a tensioning mechanism 12 is extended, and a compressive force is applied to the lower side of the middle girder part 5 so as to reinforce it. The slab is axially cut, one side part of the slab is removed while securing a single lane of the slab, and a new slab is laid. While the passage of the vehicle is secured on a newly established slab, the residual existing slab is removed, and a new slab is laid. When the laying of the slab on the newly established slab is finished and formed into a new composite girder slab 3, a PC steel 37 is tensioned in one side of an anchor part 13, the both sides of the PC steel 37 are fixed to the anchor part 13, and the middle girder 5 is prestressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a replacement method for replacing a floor slab in a bridge having a synthetic girder slab that constitutes a road surface of a road bridge or the like.

[0002]

2. Description of the Related Art In general, concrete floor slabs that constitute road surfaces such as road bridges include synthetic girder slabs and non-synthetic girder slabs. The composite girder is an integrated version of the floor slab and the steel girder that supports this floor slab, and has a structure that resists the live load from the running vehicle.The non-synthetic girder is the strength of the girder itself. The structure alone can withstand the live load from the vehicle. In recent years, due to the deterioration of concrete floor slabs that compose road surfaces such as road bridges, existing floor slabs have been removed, and floor slab replacement work has been carried out in which new floor slabs are erected. .

[0003]

By the way, in the replacement work of floor slabs for road bridges, etc., it is difficult to block the entire surface and to perform a batch construction.
Construction had to be carried out by restricting passing vehicles on one side. However, in the case of a road bridge having a synthetic girder floor slab, when the floor slabs are removed one by one in this way and the floor slabs are replaced, the girder below the removed slab becomes a non-synthetic state. If a vehicle is passed nearby, the girder may not be able to withstand the vehicle load and may buckle. Therefore, in order to prevent the buckling of the girder when replacing such a synthetic girder floor slab, a vent is provided on the bottom surface of the girder to support it. , It is difficult to install a vent on a bridge over a river or a valley because of a deep river bottom or valley, or a large amount of water.
Since the lower surface of the girder cannot be used in overpasses, etc., it was often impossible to install a vent.

The present invention has been made in view of the above circumstances, and it is possible to extremely easily replace a synthetic girder slab constituting a road bridge or the like without causing buckling or the like of the girder. It is intended to provide a plate replacement method.

[0005]

In order to achieve the above object, in the floor slab replacement method according to the first aspect, a plurality of girders arranged along the axial direction and the floor slab are integrated. In a bridge having a synthetic girder floor slab, it is a floor slab replacement method for overriding the floor slab while securing traffic on one side by switching the floor slabs one by one, and removing the existing slab. When doing so, a tensioning mechanism portion that protrudes downward by a jack is attached to the lower portion of the girder in the substantially axial center thereof,
A fixing portion is provided below the both ends in the axial direction of the girder, a lower end portion of the tension mechanism portion and the fixing portion are connected by a steel rod, and the tension mechanism portion is extended by the jack to form a jack. It is characterized in that the lower surface of the girder is brought into contact with each other so that there is no play at each contact portion, so that the girder, the tension mechanism portion and the steel rod are made into an integral structure to reinforce the girder.

[0006] That is, when the floor slab is removed, by extending the jack, the steel rod connected to the lower end of the tensioning mechanism and the lower fixing portion near both ends of the girder is tensioned. The rod and the tensioning mechanism make the truss structure reinforcing material applied, and the girder is surely reinforced in the same way as when it is supported by the vent, and the girder of the girder due to the live load by the vehicle traveling on the floor slab on one side. Although the generated stress can be reduced and the flexure can be reduced, if the stress level generated in the girder exceeds the allowable stress level in this state, the jack is further extended to give the girder a moment and axial force opposite to the external force, and It is possible to carry out the construction in a state where it can withstand a live load without reducing the degree of buckling and causing buckling. Moreover, since the jack is extended to project the connecting portion with the steel rod in the direction away from the girder, a sufficient reinforcing force can be secured with a small force. Furthermore, unlike the case where the vent is erected from the surface such as the river bottom, it does not become an obstacle on the lower surface side, and the girder fulcrum does not rise due to the jack up by the bend, and the vent is erected. There is no need for a foundation for installation, and construction costs can be greatly reduced.

The floor slab replacement method according to a second aspect is the floor slab replacement method according to the first aspect, wherein the steel rod is provided with a length adjusting mechanism, and the jack extends the tensioning mechanism portion. It is characterized in that the steel rod is contracted by the length adjusting mechanism before the operation.

That is, the respective contact points between the tensioning mechanism and the fixing portion of the girder and the steel rod are first connected, and the connecting length of each steel rod is adjusted by the length adjusting mechanism of the steel rod. This method eliminates play and allows each steel bar to be tensioned in good balance.

The floor slab replacement construction method according to claim 3 is the floor slab replacement construction method according to claim 1 or 2, in which a floor slab is newly laid on the girder and combined with the girder. before,
While tensioning the PC steel wire passed to the fixing part, release the tension of the tensioning mechanism part, gradually replace the preload put in the girder with PC steel wire, and after completion, combine the girder and floor slab to achieve the preload effect. It is characterized by being continued even after completion.

In this way, the PC steel wire is tensioned before the floor slab is integrated with the girder, and after prestressing is introduced into the girder,
Prestress is applied to the girder by combining it with the floor slab, and the stress level generated in the girder by external force is reduced. If the PC steel wire is tensioned after synthesis, the prestress that is generated is harmful because it acts on the floor slab as a tensile force.
Since it was introduced before the synthesis, it does not occur in the floor slab. With the above effects, the load bearing capacity of the bridge can be increased without impairing the load bearing capacity of the floor slab.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The floor slab replacement method according to an embodiment of the present invention will be described below with reference to the drawings. In FIG.
Reference numeral 1 is a road bridge (bridge). The road bridge 1 has a composite girder slab 3 on both sides of which a balustrade 2 is erected. The composite girder floor slab 3 has a structure in which a floor slab 6 is integrally provided on the outer girder portion 4 provided on the lower side of both sides and the middle girder portion 5 provided on the lower portion of the central portion. ing. Here, when the floor slab 6 of the road bridge 1 having the composite girder slab 3 is to be replaced, when it is necessary to secure traffic in one lane, the vehicle is allowed to pass in only one lane while the center of the floor slab 6 is being passed. The floor slab 6 is cut in the bridge axis direction along the upper flange side surface of the middle girder portion 5, and the lane slabs are replaced by one lane each.

As described above, when the floor slab 6 is replaced while securing traffic in one lane, as shown in FIG.
A support girder 10 is installed near the middle girder portion 5 on the lane side of the floor slab 6 to be removed first, and a girder reinforcement mechanism 11 is installed in the middle girder portion 5 to move the floor slab 6 to the cutter line L near its center. At, cut in the axial direction. This girder reinforcement mechanism 11
Replaces the slab on one side, cuts off traffic, and removes the slab directly above the middle girder 5 when replacing the other slabs. At that time, the middle girder portion 5 is reinforced.

That is, in the synthetic girder floor slab 3 of this type, the outer girder portion 4 and the middle girder portion 5 and the floor slab 6 are integrated to secure the strength, and therefore the middle girder is secured. When the floor slab 6 on the portion 5 is removed, the middle girder portion 5 is in a non-synthesized state, and the strength is significantly reduced as compared with the synthetic state. For this reason,
When the floor slabs 6 are replaced one by one, the above-mentioned girder reinforcing mechanism 11 is required in order to supplement the strength.

The support girder 10 supports the floor slab 6 so that the floor slab 6 does not fall off when the floor slab 6 is cut. After the replacement, the support girder 10 may or may not be removed depending on the situation. .

The girder reinforcing mechanism 11 will be described in detail. As shown in FIG. 3, the girder reinforcing mechanism 11 includes a tensioning mechanism portion 12 provided on the lower surface of the middle girder portion 5 at the central portion in the axial direction.
And a fixing portion 13 provided on the lower surface of both ends of the middle girder portion 5 in the axial direction, and a tension member 14 bridged between the fixing portion 13 and the tension mechanism portion 12.

As shown in FIGS. 4 and 5, the tensioning mechanism 12 includes a support column 21 fixed to the lower surface of the middle girder 5, and a tension member 14 provided at the tip of the support column 21. And a connection fixing portion 22 to be connected. The support pillar 21 has a jack 23 that projects the connection fixing portion 22 downward.
Is provided. The connecting and fixing portion 22 is provided at both ends with a connecting portion 26 including a pair of connecting plates 25 having holes 24 and facing each other.

As shown in FIG. 6, the fixing portion 13 includes a fixing plate 31 fixed to the lower surface of the middle girder portion 5 and fixing plates provided on both sides of the fixing plate 31 so as to face each other. The fixing plate 32 has a connecting portion 34 having a hole 33 at one end thereof. Also,
The fixing portion 13 is provided with a PC steel wire fixing plate portion 36 having a through hole 35 formed on the rear end side thereof.
The PC steel wire 37 is inserted into the C steel wire fixing plate portion 36.

The tension member 14 has a length adjusting mechanism 4 at the middle portion.
1, a pair of steel rods 14a having a fixing member 43 having a connecting hole 42 is provided at both ends thereof. The fixing member 43 is arranged between the connecting portions 26 of the connecting and fixing portion 22 and the connecting plates 25 of the fixing portion 13 constituting the tension mechanism portion 12 and between the fixing plates 32. When the fixing member 43 is arranged between the connecting plates 25 and between the fixing plates 32 in this way, the communication hole 42 of the fixing member 43 is connected to the respective hole portions 24 and 33, and in this state. Then, a tension pin 14 is inserted by inserting a connecting pin (not shown).
Both ends of are connected to the tensioning mechanism section 12 and the fixing section 13, respectively.

Further, since the steel rod 14a is threaded by rolling, it is difficult to reverse thread it. Therefore, the length adjusting mechanism 4
1 is to make a hole through which the steel rod 14a is inserted on both sides of a box made of steel plate, insert the tip of each steel rod 14a into these holes, use the flange of the box, and put the tip of the steel rod 14a through the nut. It has a fixed structure. The length of the screw can be adjusted by increasing the screw length.

Further, in the middle girder portion 5, P is formed along the lower surface thereof.
The C steel wire 37 is provided, and both ends of the PC steel wire 37 are fixed and fixed to the fixing portions 13 provided at both axial ends of the middle girder portion 5. A vibration isolator 52 is provided on the lower surface side of the middle girder portion 5 along the axial direction at intervals, and the PC steel wire 37 is supported by the vibration isolator 52 to form a PC. The steel wire 37 is prevented from swinging.

Next, a case where the floor slab 6 of the road bridge 1 is replaced by using the girder reinforcing mechanism 11 having the above structure will be described along with the procedure. (1) When the floor slab 6 is replaced while securing traffic in one lane, as described above, first, as shown in FIG. 2, the middle girder portion on the lane side of the floor slab 6 to be removed first. The support girder 10 is installed in the vicinity of 5, and the girder reinforcing mechanism 11 is installed in the middle girder portion 5, and the middle girder portion 5 is reinforced by the girder reinforcing mechanism 11.

In order to reinforce the middle girder portion 5 by the girder reinforcing mechanism 11, first, the steel rod 1 of the girder reinforcing mechanism 11 is to be reinforced.
The tension member 14 composed of 4a is tensioned to some extent by the length adjusting mechanism 41, and in this state, the tensioning mechanism 1
The jack 23 of No. 2 is extended.

By doing so, the connecting and fixing portion 22 of the tensioning mechanism portion 12 is projected downward, and the tensioning member 14 connected to the connecting portion 26 of the connecting and fixing portion 22 and the connecting portion 34 of the fixing portion 13. Is strained, and thereby the middle girder portion 5 and the girder reinforcing mechanism 11 are integrated. The external force received by the middle girder portion 5 is transmitted to the steel rod through the tension mechanism portion 12, and the bending of the middle girder portion 5 is reduced, so that the stress level due to the external force generated in the middle girder portion 5 is reduced. If the generated stress exceeds the permissible stress even with this reinforcing effect, further extend the jack 23,
The middle girder portion 5 is bent upward to generate prestress in the middle girder portion 5. This stress cancels each other because it is in the opposite direction to the stress caused by the external force. This effect adds to the above effect and improves the reinforcing effect. Due to these effects, even when the middle girder portion 5 is in the non-synthesized state, it is possible to withstand the external force including the live weight generated by passing the vehicle through the remaining floor slab 6.

When the jack 23 of the tensioning mechanism 12 is extended and the lower surface of the middle girder portion 5 is pushed up, the middle girder portion 5
The appropriate compression force is introduced while observing the detection result of the load meter 51 provided between the support column 21 and the support column 21.

(2) Next, the floor slab 6 is axially cut by a cutter line L near its center to remove one side of the floor slab 6 while securing a lane on one side of the floor slab 6. .

(3) After removing one side of the floor slab 6, as shown in FIG. 8, a new floor slab 61 such as a precast floor slab is laid on this one side. Here, the jack 23 of the tensioning mechanism portion 12 of the girder reinforcing mechanism 11 is moved back and forth to move the tensioning member 1
By adjusting the tension force by 4, the height position of the middle girder portion 5 can be easily adjusted to the height of the newly installed floor slab 61.

(4) When the new floor slab 61 is installed on one side as described above, as shown in FIG. 9, while ensuring the passage of the vehicle on the new floor slab 61, The remaining existing floor slab 6 is removed, and a new floor slab 61 is laid.

(5) After laying all the floor slabs 6, the PC steel wire 37 set in the middle girder portion 5 is tensioned to one side of the fixing portion 13 by a jack (not shown) to introduce prestress to the middle girder portion 5. . At the same time, the tension mechanism 12 of the girder reinforcement mechanism 11
The tension of the tension member 14 is released by contracting the jack 23, the connecting pin connecting both ends of the tension member 14 to the connecting portions 26 and 34 is removed, and the tension member 14 is removed.

(6) Then, as shown in FIG. 10, the tensioning mechanism portion 12 of the girder reinforcing mechanism 11 installed on the lower surface of the middle girder portion 5.
Remove.

As described above, according to the floor slab replacement method described above, when the floor slab 6 is removed, by extending the jack 23, the lower end of the tension mechanism 12 and both ends of the middle girder 5 are removed. Steel rod 14 connected to the lower fixing portion 13 in the vicinity
When the tension member 14 made of a is tensioned, this tension member 14
And the tension mechanism portion 12 provide a truss structure reinforcing material, and the middle girder portion 5 is surely reinforced as in the case of being supported by a vent, and is supported by a vehicle running on the floor slab 6 on one side. The stress generated in the middle girder part 5 due to the load is reduced,
The deflection can be reduced, and the construction can be performed in a state that can withstand the live load without causing buckling.

The jack 23 is extended so that the tension member 1
Since the connecting portion with 4 is projected in the direction away from the middle girder portion 5, it is possible to secure a sufficient reinforcing force with a small force. Furthermore, unlike the case where a vent is erected from the surface such as the river bottom, it does not become an obstacle on the lower surface side, and there is no problem that the bearing part of the middle girder part 5 rises due to jacking up. Also, there is no need for a foundation for arranging the vents, and construction costs can be significantly reduced.

Since the girder reinforcing mechanism 11 is carried in and installed under the girder, many works are manually performed. Therefore, the weight of the member should be lighter, and the diameter of the steel rod should be smaller and the number of members should be larger. If the number is too large, the force cannot be evenly transmitted due to an error in the installation length.
It was decided to attach the length adjusting mechanism 41 by dividing the space between the two. After installing the girder reinforcing mechanism 11, the steel rod length adjusting mechanism 41
Adjust to make it play-free. By this method, the steel rod can be tensioned in a balanced manner.

Further, after laying the middle girder portion 5 and the new floor slab 61 and before placing the joint concrete on the middle girder portion 5, the middle girder portion 5 is formed.
Introduce prestress by using PC steel wire. After that, joint concrete is poured to combine the floor slab 61 and the middle girder portion 5. By this method, the load bearing capacity of the bridge can be increased without lowering the durability of the floor slab 61.

[0034]

As described above, according to the floor slab replacement method of the present invention, the following effects can be obtained. According to the floor slab replacement method of claim 1, when the floor slab is removed, the jack is extended to be connected to the lower end of the tension mechanism portion and the lower fixing portion in the vicinity of both ends of the girder. When the steel rod is strained, the steel rod and the tensioning mechanism are in a state of reinforcing the truss structure, and the girder is surely reinforced as if it were supported by the vent, and the reinforcement on one side It is possible to reduce the stress generated by the girder due to the live load of the vehicle traveling on the road and reduce the deflection, and by extending the jack, a preload can be introduced into the girder, and the stress generated by the external force including the live load is reduced. Therefore, due to these effects, the construction can be performed in a state where the live load can be endured without causing buckling. Moreover, since the jack is extended to project the connecting portion with the steel rod in the direction away from the girder, a sufficient reinforcing force can be secured with a small force. Furthermore, unlike the case where a vent is erected from the surface such as a river bottom, it does not become an obstacle on the lower surface side, there is no problem such as lifting of the girder, and the basis for establishing the vent. It is not necessary, and the construction cost can be greatly reduced.

According to the floor slab replacement method of claim 2,
The respective contact points between the tensioning mechanism and the fixing portion of the girder and the steel rod are first connected, and the connecting length of each steel rod is adjusted by the length adjusting mechanism of the steel rod. This method eliminates play and allows each steel bar to be tensioned in good balance.

According to the floor slab replacement method of claim 3,
After laying the middle girder and new floor slab, before introducing concrete joints on the middle girder, to introduce prestress to the middle girder with PC steel wire, and then to combine the floor slab and middle girder , Placing joint concrete. By introducing this method, the load bearing capacity of the bridge can be increased without degrading the durability of the floor slab. After the floor slab is integrated with the girder, the PC steel wire is tensioned between the fixing portions to introduce prestress to the new floor slab, so that the load resistance of the new floor slab can be increased. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a road bridge having a synthetic girder floor slab to which a floor slab replacement method according to an embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view of a road bridge illustrating a method for replacing a floor slab according to an embodiment of the present invention.

FIG. 3 is a side view of a middle girder portion provided with a girder reinforcing mechanism for explaining the replacement method for the floor slab according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a middle girder portion provided with a girder reinforcing mechanism for explaining the floor slab replacement method according to the embodiment of the present invention.

FIG. 5 is a side view of the tensioning mechanism portion of the girder reinforcing mechanism for explaining the floor slab replacement method according to the embodiment of the present invention.

FIG. 6 is a front view of the fixing portion of the girder reinforcing mechanism for explaining the floor slab replacement method according to the embodiment of the present invention.

FIG. 7 is a side view of an end portion of the tension member of the girder reinforcing mechanism for explaining the replacement method for the floor slab according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view of a road bridge illustrating a floor slab replacement method according to an embodiment of the present invention.

FIG. 9 is a cross-sectional view of a road bridge illustrating a method for replacing a floor slab according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view of a road bridge for explaining a floor slab replacement method according to an embodiment of the present invention.

[Explanation of symbols]

1 road bridge (bridge) 3 synthetic girder floor plate 5 Middle digit (digit) 6 floor slabs 12 Tension mechanism 13 Fixing part 14 Tension material (steel rod) 14a steel rod 23 Jack 37 PC steel wire 41 Length adjustment mechanism 61 floor slab

Claims (3)

[Claims] 1. A bridge having a synthetic girder slab in which a plurality of girders arranged along the axial direction and a slab are integrated,
A method of replacing a floor slab while maintaining the traffic on one side by replacing the floor slabs one by one, wherein when removing the existing floor slab, the axial direction of the girder is approximately A tensioning mechanism portion that protrudes downward by a jack is attached to the lower part in the center, and a fixing portion is provided below the both ends in the axial direction of the girder. A lower end portion of the tensioning mechanism portion and the fixing portion are connected to a steel rod. And the tension mechanism part is extended by the jack to bring the jack and the lower surface of the girder into contact with each other, and there is no play at each contact part, so that the girder and the tension mechanism part and the steel rod are integrated with each other. And a reinforcing method for the girder, which is a replacement method for a floor slab. 2. The steel rod is provided with a length adjusting mechanism, and the steel rod is contracted by the length adjusting mechanism before the tension mechanism portion is extended by the jack. Item 1. The floor slab replacement method according to Item 1. 3. A floor slab is newly laid on the girder, and before the composite with the girder, while tensioning the PC steel wire passed to the fixing part, the tension force of the tensioning mechanism part is released, and gradually. The replacement method of a floor slab according to claim 1 or 2, characterized in that the preload put in the girder is replaced with a PC steel wire, and after the completion, the girder and the slab are combined to maintain the preload effect even after the completion. .