JPH11100812A - Box girder bridge excellent in weather resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the corrosion of box girders by vertically forming web sections on the outside of the box girders, nearly matching the web sections with the end sections of a floor board, and providing fairing mechanisms at the lower corner sections of the box girders. SOLUTION: Box girders 1 are formed with web sections 2, 2a and lower flange sections 3, and the faces of the outside web sections 2 are vertically formed. Fairing mechanisms 5 made of fins 5a are provided on the outside of the lower flange sections 3 of the box girders 1. A floor board 4 is arranged and fitted to the upper faces of the box girders 1 to form a box girder bridge so that the faces of the web sections 2 on the outside of the box girders 1 are located on the planes nearly matched with the vertical faces of the end sections 4a, 4b of the floor board 4. When the side wind colliding with the side faces of the box girders 1 is sent to the lower flanges 3 from corner sections 1a, it smoothly passes on the outside of triangular stagnation regions formed by the fins 5a, the occurrence of large swirls is prevented, and the enfolding of salinity and dust is prevented, thereby the corrosion of the box girders 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a maintenance property,
The present invention relates to a box girder bridge with excellent weather resistance.

[0002]

2. Description of the Related Art In order to use an installed bridge for a long time, various maintenances are required. In recent years, there has been a demand for minimizing the maintenance cost of bridges or providing bridges that can be easily maintained, and various studies have been made from the viewpoint of the material and structure of structural materials.

[0003] In steel bridges, iron rust is the biggest bottleneck in extending the life of the bridge, and measures to prevent rust are an important issue. It is also reported that iron rust is promoted due to salt content. In particular, it has been reported that rust is accelerated in a bridge constructed near the coast than in a mountainous bridge.

As a countermeasure against rust, there is generally a method of applying paint, and as a countermeasure against rust from the material side, a weather-resistant steel is used as a constituent member of a bridge, and stable rust generated on the surface of the weather-resistant steel is used. There is a method to prevent the progress of corrosion.

[0005]

However, the method of applying paint requires repainting every several years, and at that time, the cost of erection of a scaffold becomes large, which is problematic in terms of cost.

[0006] In addition, weather-resistant steel materials have been actively used in recent years, and the maintenance cost is lower than that of the application of paint. However, in order to generate stable rust from the mechanism of rust generation of weather-resistant steel materials, In environments where repeated sunshine / rainwashing is required, and where the amount of salt coming from the coast is high,
There is a problem that stable rust is hardly generated.

In particular, in the case of a bridge having a box girder structure, the lower surface of the box girder is easily corroded, and in a bridge in which the floor slab is overhanging from the box girder, the rain on the outer portion (web portion) of the box girder is increased. There is a problem that a portion that is not washed away due to water is easily corroded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bridge having a box girder structure and having excellent weather resistance which prevents corrosion of the box girder.

[0009]

A first means for solving the above-mentioned problem is a bridge constituted by a box girder, and a web portion outside the box girder is made to substantially coincide with an end of a floor slab. A web girder bridge excellent in weather resistance, wherein the web portion is formed vertically and a rectifying mechanism is provided at a lower corner of the box girder.

A second means for solving the above-mentioned problem is the box girder bridge excellent in weather resistance according to the first means, wherein the rectifying mechanism is constituted by fins.

A third means for solving the above-mentioned problems is a box girder bridge excellent in weather resistance according to the first means, wherein the rectifying mechanism is formed by dropping a box girder. is there.

According to the first means, the web portion of the box girder is made substantially coincident with the end of the floor slab, and the web portion is formed vertically, so that the attached salt and dust on the outer surface of the web portion can be entirely reduced. Rust can be prevented by being washed away by rainwater over the entire area. When the material of the box girder is a weather-resistant steel material, appropriate stable rust can be generated on the surface.

By providing a rectifying mechanism outside the lower part of the box girder, the flow of the cross wind does not become turbulent on the lower surface of the box girder.
By rectifying the flowing air flow, salt and dust can be prevented from adhering, and rust can be suppressed.When the box girder is made of weather-resistant steel, appropriate stable rust is generated on the surface. Can be done.

According to the second means, since the rectifying mechanism for the flow of the cross wind is constituted by fins, the cost can be reduced.

According to the third means, since the rectifying mechanism is formed by dropping the box girder, the flowing air flow can be rectified, salt and dust can be prevented from adhering, and generation of rust can be suppressed. If the material of the box girder is a weather-resistant steel material, appropriate stable rust can be generated on the surface.

[0016]

FIG. 1 is a cross-sectional view of a bridge having a box girder structure according to the present invention. Reference numerals 1 and 1 denote box girders in which a main girder of the bridge is formed in a box-shaped structure having a closed cross section. In the illustrated example, the structure is provided in pairs on both sides. Box girder 1 has web parts 2 and 2
a and the lower flange portion 3, and the surface of the outer web portions 2, 2 of the box girder 1 is on a surface almost coincident with the vertical surfaces of the ends 4 a, 4 b of the floor slab 4 as the upper structural material. And is formed vertically. With this structure, the action of washing away salt and dust by rainwater is promoted, and salt does not adhere to the surface.

A rectifying mechanism 5 is provided outside the lower flange portion 3 of the box girder 1, and a fin 5a is attached in the illustrated example. When the cross wind hitting the side surface of the box girder 1 flows from the corner 1 a to the lower flange 3, the rectifying mechanism 5 smoothly passes outside the triangular stagnation region formed by the fins 5 a, This prevents the occurrence of eddy currents, thereby preventing salt and dust from being entrained. The rectifying mechanism 5 can prevent, in particular, adhesion of salt and the like to the lower flange portion 3 of the box girder 1.
In this embodiment, since the fins 5a are used, an inexpensive rectifying mechanism can be provided.

FIG. 2 is a cross-sectional view of a bridge having a box girder structure according to another embodiment of the present invention.
Of the corners 1a and 1b.
With this structure, the cross wind hitting the web portion 2 of the box girder 1 smoothly flows into the lower flange portion 3 of the box girder 1 along the corner drop 5b, so that a large vortex is prevented from being generated. Therefore, salt and dust are prevented from being entrained, so that they do not adhere.

In the box girder 1 according to the present invention, since the web portion 2 has a vertical surface, the flow of rainwater and the like is promoted, and when a weather-resistant steel material is used, the generation of stable rust is promoted. Can be.

[0020]

The present invention is as described above. The web part of the box girder is substantially aligned with the end of the floor slab, the web is vertical, and a rectifying mechanism is provided on the lower surface of the box girder. Therefore, the washing of salt and dust with rainwater over the entire outer surface of the web portion is promoted.

Further, the air flow on the lower surface of the box girder becomes smooth, the salt and dust are prevented from adhering to the lower surface of the box girder, harmful rust is prevented from being generated, and when weather-resistant steel is used. Has the effect of promoting the generation of stable rust.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bridge having a box girder structure according to the present invention.

FIG. 2 is a cross-sectional view of a bridge having a box girder structure according to another embodiment of the present invention.

[Explanation of symbols]

 1 Box girder 22a Web part 3 Lower flange part 4 Floor slab 5 Rectifying mechanism

Claims (3)

[Claims] 1. A bridge comprising a box girder, wherein a web portion outside the box girder is made substantially coincident with an end of a floor slab, and the web portion is formed vertically, and a lower portion of the box girder is provided. A box girder bridge with excellent weather resistance characterized by a rectification mechanism at the corner. 2. The box girder bridge excellent in weather resistance according to claim 1, wherein the rectifying mechanism is constituted by fins. 3. The box girder bridge excellent in weather resistance according to claim 1, wherein the rectification mechanism is formed by dropping a box girder.