JPH0971907A - Precast concrete girder for composite floor slab bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate reinforcements projecting to the upper surface of an installed girder and increase the labor-saving and safety factors, by providing a steel plate for embedding dowels flush with the upper surface of the upper flange of a precast concrete girder for a composite floor slab bridge. SOLUTION: In a precast concrete girder 1 for a composite floor slab, an anchor rod fixed to a steel plate 5 is fixed to girder stirrups by spot welding and concrete is placed so that the upper face of flange 2 is flush with the upper face of steel plate 5. After installation of the girder 1, studs 6 are welded on the steel plate 5 and concrete for the floor slab is placed to complete the bridge body. Besides dowels, bolts are screwed in female screws provided in the steel plate, or machined steel rods are welded with the steel plate 5 for the studs 6. Accordingly, there is no projection on the surface of the upper flange 2 and no obstacles for workers and hence, cast-in-place floor slab reinforcements are easily assembled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a precast concrete girder used in a prestressed concrete (PC) composite slab bridge.

[0002]

2. Description of the Related Art In a PC bridge using a prestressed precast concrete girder, the upper surface of the upper flange of the precast concrete girder has been used as a floor slab as it is.
If there is a cross slope on the bridge surface like a curved bridge, if the slope is small, it can be adjusted with the pavement, but if the slope is large, adjusting with the pavement will increase the pavement thickness and increase the dead load. Therefore, it was necessary to form the upper flange of the precast concrete girder with a slope in accordance with the slope. Therefore, even if the bridge surface has a cross slope, the floor slab is constructed with cast-in-place concrete so that it is not necessary to incline the girder flange.
The use of precast concrete girders and synthetic slab bridges with synthetic structures has increased. An example is shown in FIGS. 5 is a side view, FIG. 6 is a sectional view taken along the line AA of FIG. 5, and FIG. 7 is a sectional view taken along the line BB of FIG. In this example, a precast concrete girder 11 is erected, and the girder spaces 13 are connected to each other on the piers 12 to form the floor slab 9 in one body.
This precast concrete girder 11 is a gibber 14,
The reinforcing bar 15 is projected. As described above, in order to make the floor slab a composite structure, it is necessary to project the dowel streak 14 for preventing slippage on the upper flange upper surface of the precast concrete girder 11, as also illustrated in FIG. It is necessary to project a large number of mating reinforcing bars 15 from the side surface of the flange. For this reason, it takes a lot of time to assemble the side formwork, and the projecting reinforcing bars 15 make it difficult to carry and handle other things. Moreover, the scaffolding on the erected girder is unsatisfactory on the girder. There was also a safety problem such as the worker getting his foot caught by the protruding reinforcing bar 14 when working or walking.

[0003]

SUMMARY OF THE INVENTION The present invention has been developed in view of such circumstances, and in a synthetic deck slab, it is necessary to prevent as many protrusions as possible from the upper surface and the side surface of the manufactured girder. The purpose of the present invention is to solve the above-mentioned drawbacks by manufacturing a girder and allowing a minimum required amount of gibber to be planted at a time when it is necessary.

[0004]

SUMMARY OF THE INVENTION The present invention is a precast concrete girder for a composite floor slab, in which cast-in-place concrete is placed to mechanically connect the girder and the slab to construct a bridge of a composite structure. In addition, the precast concrete girder for a synthetic floor slab is characterized in that it is equipped with a steel plate for dowel planting embedded flush with the upper surface of the upper flange.

The dowel may be selected from the group consisting of welded studs, welded reinforcing bars, and bolts, or a combination of these.

[0006]

FIG. 1 is a perspective view of a precast concrete girder 1 for a composite floor slab of the embodiment. Digit length is 30
m, girder width is 1.5 m, and stud diameter is d = 1.9 cm. The girder has a steel plate 5 buried in the girder flange, and after installation, the stud dowel 6 is shown. There is.

According to the specifications of the road bridge specification, the studs should be arranged in a zigzag width direction with a distance of d + 3 cm and a girder longitudinal direction distance of 5d or 10 cm, and should not be arranged in a zigzag pattern. The width of the girder is 22 cm and the thickness is 22 cm as shown in FIG.
The anchor bar 7 attached to the steel plate 5 mm of mm is positioned and fixed to the girder stirrup rebar by spot welding, and concrete is filled in the formwork so that the upper surface of the flange and the upper surface of the steel plate are flush with each other. The anchor bar 7 may be a reinforcing bar or a stud bolt may be planted. At this time, steel plate 5
It is preferable to appropriately provide an air vent small hole and an insertion hole for a concrete compacting rod-shaped vibrator because air voids do not occur on the lower surface of the steel sheet.

The girder is erected by a known method, but since there is no protrusion on the surface of the upper flange, it does not hinder the work. As shown in FIG. 2 and FIG. 3, after assembling the girder 1, after assembling the formwork of the cast-in-place floor slab 9, assembling the rebar and 1.9 cm on the steel plate 5.
The stud 6 in the inside is melted and the concrete of the floor slab 9 is placed to complete the bridge body. It is preferable that the studs 6 are welded after the floor slabs have been assembled because they do not interfere with the rebar assembly, but the parts with high reinforcement density and the work space of the stud implanter cannot be welded beforehand. I'll do it.

In this example, the stud is a gibber, but a female screw is engraved on the steel plate 5 and a bolt is screwed in to form a gibber, or a semicircle, an L-shape, a U-shape, or the like. It can also be suitably used by a method of welding the processed rebar to the steel plate 5. In this example, the studs are arranged in two rows, but the diameter, the number, and the number of rows of the studs are different in the difference in temperature between the joint surface between the girder flange surface and the cast-in-place concrete, and the temperature change. The shear shear force due to the above may be calculated and determined.

[0010]

EFFECTS OF THE INVENTION The precast concrete girder of the present invention is easy to manufacture, has no reinforcing bars protruding from the upper surface of the erected girder, is easy to assemble cast-in-place floor slabs, and does not hinder the walking of workers. It contributes to labor saving and improvement of safety.

[Brief description of drawings]

FIG. 1 is a perspective view of a girder according to an embodiment.

FIG. 2 is a cross-sectional view of a bridge body of an example.

FIG. 3 is a cross-sectional view of a bridge body of an example.

FIG. 4 is an explanatory diagram of a steel sheet of an example.

FIG. 5 is a side view of a conventional example.

6 is a sectional view taken along the line AA of FIG. 5;

FIG. 7 is a sectional view taken along the line BB of FIG. 5;

FIG. 8 is a perspective view of a conventional girder.

[Explanation of symbols]

 1 Girder 2 Flange 3 Web 5 Steel plate 6 Stud Gibel 7 Anchor bar 8 Reinforcing bar 9 Floor slab 11 Girder 12 Pier 13 Girder space 14 Gibel bar 15 Reinforcing bar

Claims (2)

[Claims] 1. A precast concrete girder for a composite deck slab, in which cast-in-place concrete is poured to mechanically connect the girder and the slab to construct a bridge body of a composite structure, the upper surface of the upper flange. A precast concrete girder for a composite deck slab, which is equipped with a steel plate for planting a dowel that is embedded flush with the floor. 2. The precast concrete girder for a composite deck bridge according to claim 1, wherein the gibber is one or more selected from the group consisting of welded studs, welded reinforcing bars, and bolts.