| 摘要 |
PROBLEM TO BE SOLVED: To present good weatherproofness so that even if the amount of scattering salt is large, iron rust is hard to generate by providing a plate girder bridge having plural plate girders formed by a web and a flange, and disposing plural holes in a designated portion of a web part of the plate girder positioned on the section side end part directly subjected to scattering of salt. SOLUTION: In a 2-main plate girder bridge or 3-main girder bridge, plural holes 5 are provided in a portion within one-third of height from the lower end of the web 3 part positioned on the section side end part directly subjected to scattering of salt. Thus, some of wind 6 flowing on the lower surface of the plate girder 2 passes through the holes 5, so that a pressure difference between the up wind surface and the down wind surface of the plate girder 2 is lessened to hardly cause entrainment of wind between the plate girders 2, thereby forming a circulating flow 8. Therefore, inflow of salt to the inner surface side of the plate girder 2 is restrained so that much salt will not adhere thereto, whereby the generation of iron rust can be restrained. A cut surface produced in boring is preferably subjected to rust-proof processing such as application of paint.
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