JPH086291B2 - Widening method of road bridge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floor slab widening method for increasing the effective width of a road shoulder portion and a sidewalk in a road bridge composed of a main girder and RC floor slab.

[0002]

2. Description of the Related Art Road bridges constructed under the old standard have a width of 6
Since there are many m or less, it is not possible to secure shoulders and sidewalks for emergency vehicles, and there are many requests to increase the width of the floor slab. Conventionally, when the existing floor slab has an RC (reinforced concrete) structure, as shown in FIGS. 5 and 6, the overhanging portion 3 on the outside of the main girder 1 of the floor slab 2 is appropriately located between the main girder 1 and the ground cover 15. After cutting and removing with a concrete cutter etc. at various positions 5 to expose the main rebar 6, the form frame 9 of the widening part and the main rebar 6 ′ are laid out and connected to the existing main rebar 6 to be integrated.
Construction is done by the procedure of placing concrete 11. 4 is the last pavement.

[0003]

By the way, in the above-mentioned conventional construction method, the strength of the main girder is insufficient due to the increase of the floor slab weight, the amount of reinforcing bars above the main girder is insufficient, and the durability of the concrete joint is insufficient. In addition to many strength weaknesses remaining, hardening of the concrete in the extension part, long curing period,
There are problems such as long traffic regulation period due to construction.

An object of the present invention is to provide a method for widening a road bridge that solves the above problems.

[0005]

In order to achieve the above object, the present invention provides a step of mounting a cantilever girder by projecting from the main girder, and a projecting portion outside the main girder of the RC floor slab with the main girder and the ground cover. A step of cutting and removing at a suitable position in the middle of to expose the main rebar of the RC floor slab end, a step of loading a lightweight steel deck to the removed part and placing it on the cantilever girder, The step of connecting the main rebars at the connecting portion between the RC floor slab and the steel floor slab and injecting a filler into the space of the same to integrate them.

[0006]

[Operation] According to the present invention, an increase in the weight of the floor slab is significantly suppressed, and since the amount of concrete placed is small, rapid construction is possible.

[0007]

Embodiments of the present invention will be described in detail with reference to FIGS. The road bridge before the start of construction is the same as that shown in FIG. 5, and the same reference numerals are used in the drawing. First, prior to floor slab construction, a cantilever girder 12 is attached to the main girder 1 as shown in FIG. This cantilever girder 12 is attached to the vertical gusset 8 welded to the abdominal plate of the main girder 1 or attached with bolts or the like with bolts or the like. This work can be done before the construction period regardless of the traffic on the bridge. At this time, when only the main girder and the cantilever girder attached to it cannot withstand the dead load and the live load after the widening, it is preferable to use a transverse girder 16 or the like to make the girder part have a strong structure.

Next, the overhanging portion 3 on the outside of the main girder 1 of the existing RC floor slab is cut and removed in the axial direction of the bridge using a concrete cutter or the like at an appropriate position 5 between the main girder and the ground cover. The rebar 6 is exposed. Subsequently, as shown in FIG. 2, the steel deck 13 separately manufactured in the factory is carried in and placed on the cantilever girder 12 attached to the front. In this steel deck, a steel plate is used as a top plate, and a rib material 14 is appropriately welded to the lower portion thereof, and cut into an appropriate length that does not hinder transportation. In order to improve the efficiency of on-site construction, it is desirable to attach ground cover 15 and drainage equipment (not shown) to this steel deck in advance.

Next, in order to connect and integrate the steel floor slab 13 and the existing RC floor slab 2, as shown in FIG. 3 and FIG. 4 showing the details of this portion, the existing RC floor slab side main rebar 6 and extension main rebar 7 are connected. Are connected by welding or a coupler with screws. After a while,
Filling material such as high-strength concrete is injected into the connection space 17 and cured. The RC floor slab, which is about 18 cm thick, weighs about 450 kg per 1 m ² , but the steel floor slab weighs about 240 kg, which is about half the weight, and the dead load moment on the main girder is reduced. There are no strength problems. In the case where the widening width is large or the main rebar of the existing RC slab is originally insufficient, the connecting steel plate 18 is used in addition to the above steps. This connecting steel plate does not need to be continuous in the bridge axis direction, and it is sufficient to dispose strip-shaped steel plates intermittently. Welding or bolting is used to connect the connecting steel plate and steel deck, and hole-in anchors or chemical anchors that have a screw on the head and can be driven or fixed to concrete are used to connect the connecting steel plate and RC deck. What is called is convenient in terms of workability. Finally, pavement 4 is performed on the entire road surface to complete the construction.

[0010]

According to the present invention, since the increase in the weight of the floor slab is significantly suppressed, the stress load on the main girder is not increased, and the concrete placing amount is small, so that the rapid construction is possible and the long-term construction is possible. Traffic regulation is unnecessary.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a road bridge showing a state in which a cantilever girder is attached in the present invention.

FIG. 2 is a sectional view of a road bridge showing a state where a steel deck is placed on a cantilever girder in the present invention.

FIG. 3 is a sectional view of the road bridge showing the final stage in the present invention.

FIG. 4 is a detailed view of a connecting portion at the stage of FIG.

FIG. 5 is a cross-sectional view of the road bridge showing a state before construction.

FIG. 6 is a cross-sectional view of a road bridge showing a conventional technique.

[Explanation of symbols]

 1 Main girder 2 RC floor slab 5 Cutting position 6 Main rebar 12 Cantilever girder 13 Steel deck slab 17 Connection space 18 Steel plate for connection

Claims (1)

[Claims] 1. A method for widening a road bridge comprising a main girder and an RC floor slab, comprising a step of mounting a cantilever girder by extending from the main girder, and a projecting portion outside the main girder of the RC floor slab. A step of cutting and removing at an appropriate position between the main girder and the ground cover to expose the main reinforcing bar at the end of the RC floor slab, and carrying a lightweight steel deck to the removed part and placing it on the cantilever girder. And a step of connecting the main rebars at a connecting portion between the RC floor slab and the steel floor slab and injecting a filler into the space of the same to integrate them, a method for widening a road bridge.