JPS584125B2 - Railing construction method for road bridges, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to road bridges, etc. that utilize glass fiber reinforced concrete slabs (hereinafter referred to as "GRC slabs"), which are formed by molding a material in which glass fibers are mixed into cement or mortar into slabs. This paper relates to a method of constructing a balustrade.

For the construction of general handrails, after the floor slab concrete is poured and hardened,
A construction method is used in which a steel or wooden formwork is set up, concrete is poured, and the formwork is removed after the concrete has sufficiently hardened.

However, when using this construction method, the following problems are likely to occur.

(i) It may be difficult to ensure the correct cover thickness of the reinforcing bars, and due to exposure of the reinforcing bars to the concrete surface and lack of cover, the reinforcing bars will rust and increase the frequency of repair of the balustrade.

In other words, because this type of railing is relatively thin, when the above-mentioned construction method is used to place formwork on both sides of the reinforcing bars, there may be places where the reinforcing bars come into contact with or abnormally approach the inner surface of the formwork. It is difficult to prevent this from occurring.

Therefore, in conventional railings, reinforcing bars are exposed on the outside,
Even if it is not exposed, areas where the concrete cover thickness against the reinforcing steel is insufficient are likely to occur.

(ii) There may be spots on the joint surface between the deck slab and the railing concrete that do not completely adhere, which not only deteriorates the appearance due to water leakage, but also causes corrosion of the reinforcing bars.

(iii) When a vehicle collides with a handrail due to a vehicle accident, the handrail concrete is damaged, and its fragments sometimes fall from road bridges and cause accidents on general roads.

In addition, as shown in Fig. 3, conventionally, it was common to provide a drain b with a concave cross section near the side edge of the lower surface of the deck slab a, so the reinforcing bar cover thickness at the drain b portion was reduced. Rust is likely to occur.

Therefore, there is a problem in that the reinforcing bars rust and expand in this area, and the concrete in the shaded area C in FIG. 3 is likely to peel and fall.

In recent years, road bridges and the like are often installed alongside other facilities such as streets and parks in order to make effective use of urban space.

Therefore, the problem of concrete that makes up handrails and deck slabs peeling off and falling is an extremely serious and serious problem in that it may cause secondary disasters under roads, and the solution to this problem is urgent. This has become an issue for the shield.

The present invention was made in view of these circumstances, and
When constructing railings for deck slabs of road bridges, etc., instead of using conventional concrete formwork, a GRC plate previously formed into a predetermined size and shape is used as the formwork, and concrete is poured. By integrating the GRC slab with the concrete, a composite structure of the GRC slab and concrete is formed, and the GRC slab is combined with a hard plate part whose lower end is to be attached to the side surface of the floor slab, a bent plate part which is provided continuously at the lower end of the hard plate part and which should embrace the lower side edge of the floor plate; and a horizontal plate part which extends from the bent plate part to be attached to the lower surface of the floor plate. By adopting a method of pre-forming the cross plate into a shape that is integrally equipped with a drainer that forms a protrusion provided on the lower surface of the horizontal plate, all of the various problems mentioned above can be completely solved. The purpose of the present invention is to provide a method for constructing handrails for road bridges, etc., that makes it possible to do so.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 indicates a deck slab of a road bridge constructed by a conventional method, and reinforcing bars 2 for a handrail are erected at the side edges of this deck slab 1.

First, as shown in FIG. 1, GRC plates 3 and 4 are placed on both sides of the reinforcing bar 2 instead of the conventional iron or wooden formwork, and between these GRC plates 3 and 4, Concrete 5 is poured and the concrete 5 and the GRC plates 3 and 4 are placed.
By integrating the G
A parapet 6 having a composite structure of RC plates 3 and 4 and concrete 5 is obtained.

The GRC plates 3 and 4 are thin plate-shaped plates that are preformed and hardened in a factory or the like, and are manufactured by two-dimensionally dispersing a large amount of glass fibers in concrete.

As for the adhesion strength between these GRC plates 3 and 4 and the concrete 5, a sufficient value can be obtained by making the inner surface of the GRC plates 3 and 4 slightly rough, but for safety reasons, Even higher adhesion performance can be obtained by processing and attaching appropriate anchors or wire mesh to the inner surfaces of the GRC plates 3 and 4.

The lower end of the outer GRC slab 3 extends below the pouring surface 7 of the concrete 5 so as to encompass the side and lower side edges of the floor slab 1. A drainer 8 is formed in the part.

That is, the GRC slab 3 has a hard board part 3a whose lower end is to be attached to the side surface of the floor slab 1, and a hard board part 3a which is provided continuously to the lower end of the hard board part 3a and extends along the lower side edge of the floor slab 1. A supporting bent plate portion 3b, a horizontal plate portion 3c extending from the bent plate portion 3b to be attached to the lower surface of the floorboard, and a drainer 8 forming a protrusion provided on the lower surface of the horizontal plate portion 3c. As mentioned above, it is made by molding and hardening in advance in a factory or the like.

The shape of the railing shown in FIGS. 1 and 2 is merely an example, and various modifications can be made without departing from the spirit of the present invention.

According to the above-mentioned balustrade construction method, the following advantages can be obtained.

(i) The strength of the balustrade can be significantly improved.

The bending strength of the GRC plate is approximately 300 kgf/cm2, and the adhesion between the GRC plate and post-cast concrete is sufficient. Therefore, the static properties of the GRC-concrete composite are significantly increased in cracking strength and shear resistance. Is recognized.

These characteristics are fully demonstrated dynamically, so shear,
Punching shear-like damage can be significantly reduced, and 2
Dimensionally randomly distributed glass fibers can prevent fragments from scattering when the parapet is damaged.

Therefore, it is possible to effectively prevent inconveniences such as concrete fragments falling from a road bridge or the like in the event of a vehicle accident and causing an accident on a general road.

(ii) Workability and durability GRC plates are used as formwork when pouring concrete for parapets, and after the concrete has hardened, they are used as exterior materials, so they need to be demolded unlike conventional construction methods that use steel or wooden formwork. It is possible to simplify the construction without any problems.

In addition, the cover of the railing reinforcement reinforcement is approximately 30% of the water-cement ratio.
Since this can be forcibly secured by the dense and watertight GRC plate (plate thickness of about 10 to 20 mm), the reinforcing bars can be sufficiently protected even if a predetermined cover cannot be maintained.

In other words, when GRC plates are placed on both sides of reinforcing bars, even if there is a point where the reinforcing bars come into contact with or abnormally approach the inner surface of the GRC plates, the GRC plates cannot be removed like conventional formwork. Since the balustrade is constructed by integrating with the concrete rather than the balustrade, the reinforcing bars will not be exposed on the outer surface of the completed balustrade and the covering will not be extremely insufficient.

(iii) Crack resistance The GRC plate has excellent ability to disperse cracks due to the glass fibers mixed therein, so drying shrinkage cracks in post-cast concrete can be finely dispersed.

It is also possible to control the crack position at the seam of the GRC plate.

(iv) Economical efficiency The unit price per square meter of this construction method is not significantly different from that of conventional construction methods.

Additionally, due to its excellent durability, repair costs can be significantly reduced.

(v) Aesthetic GRC plates have excellent formability during production and can be given any shape or pattern.

Therefore, it is possible to design a road bridge with an aesthetically pleasing design by optimizing the shape of the ditch and using curved surfaces.

Further, as in the above embodiment, it is possible to easily extend the lower end of the external GCR slab 3 to the lower surface of the floor slab 1 and cover the pouring surface 7 of the concrete 5. By doing so, it is possible to prevent inconveniences such as a gap large enough to leak water at the joint surface 7, spoiling the overall appearance of the road bridge, or rusting of the reinforcing bars at the joint surface 7.

(vi) Relationship with the drainer As described above, the outer GRC plate 3 includes the hard plate portion 3a, the bent plate portion 3b, the horizontal plate portion 3c, and the drainer 8 protruding from the lower surface of the horizontal plate portion 3c. If the GRC slab 3 is used to construct the balustrade 6, the side 1 edge and lower surface of the floor slab 1 will be integrated with the bent plate part 3b and the horizontal plate part. 3c for protection, and a drainer 8 is placed on the lower surface of the floor slab 1.

Therefore, the trouble of forming a special drain on the lower surface of the floor slab 1 can be saved (since the GRC slab 3 can be industrially mass-produced, it is easy to form the drain 8 integrally with the GRC slab 3). ).

Moreover, the drainer 8 provided in this manner does not cause the inconvenience of reducing the reinforcing bar cover thickness on the lower surface of the floor slab a, unlike the conventional concave drainer b shown in FIG. The reinforcing bars in the floor slab 1 will be effectively protected by the GRC slab 3.

Therefore, as shown in FIG. 3, it is possible to reliably eliminate the inconvenience that the reinforcing bars rust and expand on the lower surface of the floor slab a, causing the concrete in the shaded area c to peel and fall easily.

Therefore, in combination with the effect of item (1) above that scattering of debris when the railing 6 is damaged can be prevented, it is possible to effectively eliminate the serious problem of inducing secondary disasters under the road due to falling concrete pieces. You can get excellent results.

Further, the GRC plate 3 is made such that a bent portion 3b is interposed between the hard plate portion 3a and the horizontal plate portion 3c, and a drainer 8 forming a protrusion is integrally formed on the horizontal plate portion 3c. By doing so, the strength and rigidity of the GRC plate 3 can be increased, making it easier to handle the GRC plate 3, for example, when transporting it from the factory to the site or when using the GRC plate 3 as a formwork. It also has the advantage of being easy to use.

As can be seen from the above description, the present invention has characteristics that are significantly superior to conventional balustrade construction methods, and is worthy of attention as a future balustrade construction method.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of the railing before concrete is poured, and FIG. 2 is a cross-sectional view of the railing after concrete is poured. FIG. 3 is a sectional view for explaining a conventional example. 1... Floor slab, 2... Rebar, 3, 4... Glass fiber reinforced concrete version (GRC version), 5... Concrete, 6... Railing, 3a... Hard board part, 3b ...Bending plate part, 3c...Horizontal plate part, 8...Drainer.

Claims (1)

[Claims] 1 When constructing railings for deck slabs of road bridges, etc., instead of using conventional concrete formwork, glass fiber reinforced concrete slabs, which have been formed into predetermined dimensions and shapes, are used instead of the formwork, and concrete is poured into the formwork. By integrating concrete and the glass fiber reinforced concrete slab,
A parapet construction method having a composite structure of the glass fiber-reinforced concrete slab and concrete, wherein the glass fiber-reinforced concrete slab to be placed outside is attached at its lower end to the side surface of the deck slab. a hard plate part, a bent plate part that is provided continuously at the lower end of the hard plate part and should embrace the F side edge of the floor slab; Parapet construction for road bridges, etc., characterized in that it is preformed into a shape that is integrally equipped with an extended horizontal board part and a water cutter that forms a protrusion provided on the lower surface of this horizontal board part. Method.