JPH0621929Y2 - Reinforcement structure of bridge reinforced concrete floor slab - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a reinforcing structure for a bridge reinforced concrete slab used for reinforcing a reinforced concrete slab for a bridge by using a main girder.

[Prior Art] The reinforced concrete floor slabs that make up the bridge may crack due to repeated loading, or may crack due to deterioration.
Reinforced concrete slabs for bridges have been conventionally reinforced.

The conventional reinforcement method for reinforced concrete floor slabs is
As shown in the figure, the reinforced concrete floor slab b is located between the main girders a.
In most cases, a steel plate d is attached to the lower surface of the plate using an anchor bolt c or an adhesive to reinforce a portion where cracks e are easily formed or a reinforced concrete floor slab b in which cracks are formed.

[Problems to be Solved by the Invention] However, in the above-described conventional reinforced concrete floor slab reinforcement method, since the steel plate d is fixed to the lower surface of the floor slab b by fixing it, the floor slab b and the steel plate d are fixed. If water enters between them and accumulates, it becomes difficult to escape, so the accumulated water freezes and the steel plate d peels off, or the floor water b deteriorates faster than usual due to the accumulated water. There is a risk of
Moreover, since the lower surface of the floor slab b is entirely covered with the steel plate d, there is a problem that the progress of the crack e cannot be grasped.

Therefore, the present invention is intended to solve the problems of the conventional method by reinforcing the floor slab without fixing the steel plate to the lower surface of the reinforced concrete floor slab.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention arranges a tie rod between main girders arranged in parallel to the bridge axial direction for supporting a reinforced concrete floor slab, It is fixed to the main girder upper flange so that a tensile force is applied between the main girders. Also, a turnbuckle is attached in the middle of the tie rod so as to give a prestress to compress the lower side of the reinforced concrete floor slab.

[Operation] When a reinforced concrete floor slab supported on the main girder receives a bending moment such that it is bent downward by receiving a load from above, compressive stress is generated on the upper side of the floor slab and Tensile stress acts on each of the main girders, and the space between the main girders that supports the floor slab is affected by the tensile stress so that the upper girder flanges are connected with tie rods. It is possible to suppress the spread of the slab and reduce the downward bending that acts on the floor slab. Further, if the floor slab is prestressed, the downward bending can be eliminated, the cracks generated on the lower side of the floor slab can be closed and adhered, and the floor slab can be protected.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention, in which a haunch portion 2a of a reinforced concrete floor slab 2 is erected on a main girder upper flange 1a on a main girder 1 extending parallel to the bridge axis direction. A tie rod 5 whose length is adjusted by a turnbuckle 4 in a structure in which it is fixed via a provided dowel 3.
Each free end side of a and 5b is connected to the main girder upper flange 1a via the connecting metal piece 6, and the floor slab 2 is reinforced by the tensile force of the tie rods 5a and 5b. As shown in FIG. 2 in detail, the above-mentioned connecting hardware 6 has bolts 7 on the main girder upper flange 1a.
A plate 9 having a hole 8 through which it passes and an eye plate 10 bolted to the tie rods 5a and 5b are integrally formed. 11 is a crack, 12 is a locking nut, and 13 is a reinforcing bar.

Upper flange of main girder 1 supporting reinforced concrete floor slab 2
If the main girders 1 are connected to each other by the tie rods 5a and 5b as described above and the main girders 1 are set to have a predetermined tensile force, for example, the load when the vehicle passes over the floor slab 2 is increased. When a bending moment acts such that the floor slab 2 bends downward, the tensile stress acting on the lower side of the floor slab 2 tries to widen the space between the main girders 1 by pulling the tie rods 5a and 5b. The pulling force of the tie rods 5a, 5b can be transmitted to the floor slab 2 through the joint between the connecting metal piece 6, the main girder upper flange 1a, the dowel 3 and the floor slab haunch portion 2a. It acts to reduce the bending moment of 2. As a result, the floor slab 2 is reduced in the amount of downward deflection even if it receives a load from above, and cracks
The degree of entry of 11 can be reduced, and the crack 11 that has already entered can be prevented from becoming large.

Next, tighten the turnbuckle 4 connecting the tie rods 5a and 5b to give a large tensile force so as to draw the tie rods 5a and 5b toward each other. Since it is transmitted to the floor slab 21 through the joint between the upper flange 1a, the dowel 3 and the floor slab haunch portion 2a,
A prestress is applied so that the floor slab 2 bends upward.
As a result, the cracks 11 contained in the floor slab 2 are closed, and the floor slab 2 can be prevented from bending downward even when a load is applied to the upper surface of the floor slab 2. In an experiment by the present inventor, in the reinforced concrete floor slab 2 through the tie rods 5a and 5b.
When 4 tons of prestress was applied to and loaded, the flexure of the floor slab 2 was 37% of that of the non-reinforced floor slab, and the maximum stress of concrete was reduced to 33%. Now, showing the relationship between the load and the deflection, the results shown in FIG. 3 were obtained.
In the figure, a curve I shows the case of an unreinforced floor slab, the deflection is 13 mm when the load is 9 tons, and the deflection is about 6.4 mm when the load is 5 tons. On the other hand, as shown in FIG. 1, when tie rods 5a and 5b are arranged below the floor slab 2 to reinforce by connecting the main girder upper flanges 1a to each other and prestress to the floor slab 2 is zero, As shown by curve II, the deflection when a load of 9 tons is applied is approximately 4.9 mm, and a load of 5
Deflection when applying tons is reduced to about 3.1 mm, and when the floor slab 2 is prestressed with 4 tons, the curve III
As shown in, the flexure of the floor slab 2 when a load of 9 tons was applied was about 1.9 mm, and the load of the floor slab 2 when a load of 5 tons was applied was zero.

Also, regarding the strains on the upper and lower sides of the floor slab 2 when a load is applied to the floor slab 2 from above, a load of 5 tons is applied to the floor slab 2 having reinforcing bars 13 arranged on the upper and lower sides. At this time, in the case of the unreinforced floor slab, as shown in FIG. 4 (A), the upper side of the floor slab 2 is greatly compressed, and the lower side thereof is largely stretched, resulting in a large strain. On the other hand, when the floor slab 2 is reinforced with tie rods 5a and 5b as shown in FIG.
As shown in FIG. 4 (B), the strain generated on the upper and lower sides of the floor slab 2 is greatly reduced, and when the floor slab 2 is prestressed with 4 tons by the tie rods 5a and 5b, , Fig. 4
As shown in (C), the strains on the upper and lower sides of the floor slab 2 are further reduced, and the strain generated on the lower side of the floor slab 2 is also on the compression side, so that the tensile stress does not act on the floor slab 2. Become.

Next, FIG. 5 shows another embodiment of the present invention.
In the embodiment shown in the drawing, the tie rods 5a, 5b are connected to the main girder upper flange 1a through a connecting metal 6, and the tie rod 5 is attached to the main girder upper flange 1a by a hook structure without welding. It was done like this. That is, the tie rod 5 is made to penetrate the top portion of the main girder 1, and the threaded portion is provided at the location of the penetration portion of the tie rod 5.
14 is provided. On the other hand, the tie rod 5 is attached to the main girder upper flange.
As shown in FIG. 6, the hook hardware 15 for joining to 1a is
A hook portion 17 is formed on one side so that a concave portion 16 is formed on the upper surface in consideration of a bending moment from above and the end of the main girder upper flange 1a to be positioned on the concave portion 16 is fitted. In addition, when the tie rod 5 is joined to the main girder upper flange 1a, a hole 18 for penetrating the tie rod 5 is provided in the central portion.
And hook into the surface side so that the main girder 1 is sandwiched between them.
15 through the tie rod 5, and then hook each hook portion 17 of both hook hardware 15 on the main girder upper flange 1a, and then the nut 20 through the washer 19 fitted on the tie rod 5 to the screw of the tie rod 5. Tighten along section 14 to tighten nuts 20 and 21
The hook hardware 15 is fixed to the tie rod 5.

When such a joining method of the main girder upper flange 1a and the tie rod 5 is adopted, the tensile force by the tie rod 5 can be transmitted to the main girder upper flange 1a through the hook metal fitting 15, and the main girder upper flange 1a can , Gibel 3 and slab 2 haunch
It will be transmitted to the floor slab 2 via the joint of 2a.

According to the embodiment shown in FIG. 5 above, when the tie rod 5 and the main girder upper flange 1a are joined together, the hook hardware 15 and the tie rod 5 are simply fixed with the nuts 20 and 21, and the washer 19, so that it is possible to carry out the work in the field. Work is easy, and there are no welding points, and the nuts 20 and 21 are loosened to attach the hook metal fitting 15 to the main girder upper flange 1
If it is removed from a, it will come apart, so it is easy to remove, and there are advantages such as no stress concentration.

The tie rod 5 is used in the embodiment shown in FIG.
The main girders 1 may be penetrated as a series, that is, without a turnbuckle, or may be prestressed by the turnbuckle 4 as in the embodiment of FIG. In the embodiment shown in FIG. 1, the tie rods 5a and 5b need to have a substantially constant tension, but in this case, a torque wrench may be used.

[Effects of the Invention] As described above, according to the reinforcing structure for a bridge reinforced concrete floor slab of the present invention, the upper flanges of the main girders that support the reinforced concrete floor slab are connected by tie rods, and the lower side of the reinforced concrete floor slab is connected. Since a tensile force is applied between the main girders with the main girder, when a load acts on the reinforced concrete floor slab from above, compressive stress acts on the upper side of the slab and tensile stress acts on the lower side. The space between the main girders can be suppressed by the tensile force between the main girders due to the tie rods, and the downward bending of the floor slab can be reduced with a simple structure, and the tensile force between the main girders due to the tie rods can be reduced. By pre-stressing the reinforced concrete floor slab by increasing the height of the floor slab, it is possible to prevent the floor slab from bending downward even when a load is applied to the upper surface of the slab, The cracks contained in the floor slab are closed and adhere to each other, so that the floor slab can be more sufficiently protected.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a reinforcing structure of a bridge reinforced concrete floor slab of the present invention, FIG. 2 is a side view of a connecting metal article for connecting a main girder upper flange and a tie rod in FIG. 1, and FIG. Shows the relationship between the load acting on the reinforced concrete floor slab and the flexure, and Figures 4 (A) (B) (C) show the relationship between the load acting on the reinforced concrete floor slab and the strain.
(A) shows the case of an unreinforced floor slab, Fig. 4 (B) shows the case of applying a tensile force with a tie rod for reinforcement, and Fig. 4 (C) shows the prestressing of the floor slab via the tie rod. FIG. 5 is a sectional view showing another embodiment of the present invention, FIG. 6 is a perspective view of a hook metal piece used in the embodiment of FIG. 5, and FIG. 7 is a conventional reinforced concrete floor. It is a figure which shows the reinforcement state of a plate. 1 ... Main girder, 1a ... Main girder upper flange, 2 ... Floor slab, 4 ...
… Turnbuckles, 5,5a, 5b …… Tie rods, 6 …… Coupling hardware, 15 …… Hook hardware.

Claims (2)

[Scope of utility model registration request] 1. An upper flange of main girders arranged in parallel for supporting a reinforced concrete floor slab is connected to each other via tie rods for suppressing the spread between the main girders. Reinforced structure of reinforced concrete slab for bridge. 2. A reinforced structure for a bridge reinforced concrete floor slab according to claim 1, wherein a turn buckle is attached to a tie rod connecting the upper flanges of the main girders, and the turn buckle applies prestress to the reinforced concrete floor slab. .