JPH0480161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for introducing prestress into a bridge girder.

BACKGROUND OF THE INVENTION In general, the cross-sectional size of a bridge girder increases considerably as its own weight, span, and live load increase. In particular, the dead weight of a precast concrete bridge girder is much greater than that of a steel bridge girder, and the cross-sectional size of the main girder is further increased because it is necessary to pour concrete between these members to integrate them. In this case, the cross-sectional size has been reduced by introducing prestress directly into the bridge girder using prestressing steel, but it is necessary to introduce a considerably large tension per prestressing steel.
Various devices are used that can handle this.

Problems to be Solved by the Invention For this reason, conventional bridge girders require a lot of heavy machinery and have the disadvantage of being easily upsized.

Additionally, as the height of the bridge girder increased, the height beneath the bridge girder became lower, which sometimes caused problems for ships and automobiles.

Furthermore, the method of introducing prestress using prestressing steel for bridge girders is mainly implemented for precast concrete bridge girders, but not for steel bridge girders.

This invention was proposed to solve the above-mentioned conventional problems, and it is possible to introduce prestress not only to precast concrete bridge girders but also to steel bridge girders, and moreover, it can be introduced with small-scale equipment. It is an object of the present invention to provide a method for introducing prestress into a bridge girder, which can reduce the cross section of the bridge girder.

Means for Solving the Problems The method of introducing prestress into a bridge girder according to the present invention involves constructing a plurality of bridge girders having a plurality of shear connectors on the sides between the piers in parallel, and inserting PC steel materials between the left and right bridge girders. The bridge girder is constructed along the longitudinal direction, concrete is poured between the left and right bridge girders, and after the concrete hardens, axial force is introduced into the prestressing steel material to introduce prestress into the bridge girder. In this way, the above objective is achieved.

EXAMPLE Hereinafter, a method for introducing prestress into a bridge girder according to the present invention will be explained step by step.

A plurality of main girders 1, 1 made of precast concrete are erected in parallel between piers 2, 2.
Grooves 3, 3 of a predetermined width are provided between the left and right main girders 1, 1 over the entire length of the main girder 1.
a, 1a are formed over the entire length of the main girder 1 to completely close it. In addition, a plurality of shear connectors 4 made of precast concrete, reinforcing bars, stud bolts, etc. are attached to the side surfaces of the main girder 1, that is, on both sides of the groove 3.
Formed over the entire side surface of the

In the embodiment, when the main girder 1 is molded, it is formed integrally with the main girder 1 using precast concrete.

Subsequently, the prestressing steel material 5 is erected in the groove 3 between the main girders 1 and 1 along the longitudinal direction of the main girder 1. PC
The central part of the steel material 5 is suspended downward in an arc shape or stretched upward in an arc shape (Figs. 2 and 3).
(see figure). Further, horizontal tightening bolts or PC steel materials 10 are inserted in the width direction of the main girders 1,1. Bolts or PC steel materials 10 are inserted at regular intervals in the longitudinal direction of the main girder 1 including at least the center of the main girder.

Subsequently, concrete 6 is placed in the groove 3 between the main girders 1, 1 over the entire groove 3, and is cured until the concrete 6 is sufficiently hardened.

Subsequently, when the concrete 6 is sufficiently hardened and the left and right main girders 1, 1 are integrated, a prestress of a predetermined amount is introduced into the bridge girder by tensioning or compressing the PC steel material 5. Also, bolts or
By tightening or tensioning the PC steel material 10, prestress is also introduced in the width direction of the main girder 1. In addition, if necessary, the inside of main girder 1 can also be installed as before.
Prestressing using prestressing steel may also be introduced.

Figures 4 and 5 show an H-shaped cross section and an I-shaped cross section as the main girder 1.
This figure shows a bridge girder made of shaped steel with a shaped cross section, and the construction method will be explained step by step below.

In FIG. 4, a plurality of main girders 1, 1 made of section steel with an H-shaped cross section are constructed parallel to each other between piers 2, 2 and separated by a predetermined distance in the width direction of the main girder 1. On both sides of the web portion 1b of the main girder 1, a plurality of shear connectors 4 are formed over the entire web portion 1b by welding reinforcing bars, stud bolts, or small pieces of plates. In the embodiment, the shear connector 4 is formed from a small plate. Further, the lower end portion between the left and right main girders 1, 1 is completely closed by installing a plate 9 between the flange portions 1c, 1c of the left and right main girders 1, 1. Plate 9 is welded to flange portion 1c.

Subsequently, the PC steel material 5 is erected between the left and right main girders 1, 1 along the longitudinal direction of the main girder 1 (see FIGS. 2 and 3).

Subsequently, the concrete 6 between the left and right main girders 1, 1 is sufficiently cured until it hardens.

Subsequently, when the concrete 6 is sufficiently hardened and the left and right main girders 1, 1 are integrated, a prestress of a predetermined amount is introduced into the bridge girder by tensioning or compressing the PC steel material 5.

Figure 5 shows that in cases where it is not necessary to introduce prestress using prestressing steel materials, prestressing the left and right main girders 1, 1, and 1 without installing prestressing steel materials between the left and right main girders 1 and 1 is not necessary.
This embodiment shows a case where cavities 7 are provided at every one to two locations throughout the entire length of the bridge girder, and the cavities 7 are used as spaces for passing communication cables and water pipes.

FIG. 6 shows a bridge girder using a steel pipe with a circular cross section as the main girder 1, and the method of introducing prestress is almost the same as that shown in FIG.

A slab 8 made of cast-in-place concrete or the like is constructed on the bridge girder constructed by this method.

Effects of the Invention This invention has the following effects because it has the above configuration.

When introducing prestress to a bridge girder constructed using precast concrete members as the main girder, do not insert the prestressing steel directly into the main girder.
By inserting prestressed steel material between the left and right main girders and introducing axial force into it, it is much easier to introduce the necessary amount of prestress than with conventional methods, and the cross section of the main girder can be reduced. .

In addition, if the conventional prestress introduction method using prestressed steel materials inserted directly into the main girder and the prestress introduction method of the present application using prestressed steel materials inserted between the left and right main girders are used together, it is possible to The forces can be significantly reduced, resulting in smaller pretensioning benches and other equipment and machinery.

Furthermore, since prestress can be introduced even when section steel is used as the main girder, it is extremely practical.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a sectional view of a bridge girder, Figures 2 and 3
The figure is a side view of a bridge girder showing the installed state of prestressed steel, FIGS. 4 to 6 are cross-sectional views of bridge girders showing other embodiments of the present invention, and FIG. 7 is a cross-sectional view of a conventional bridge girder. 1... Main girder, 2... Pier, 3... Groove, 4...
Shear connector, 5...PC steel material, 6...Concrete, 7...Cavity part, 8...Slab, 9...Plate.

Claims (1)

[Claims] 1. A plurality of main girders having multiple shear connectors on the sides are erected in parallel between the piers, and prestressed steel is erected along the longitudinal direction of the bridge girders between the left and right girders, and then concrete is installed between the left and right girders. Then, after the concrete hardens, the PC
A method for introducing prestress into a bridge girder, which is characterized by introducing prestress into the bridge girder by introducing axial force into the steel material.