用宽板试验研究铁路钢桥的抗断裂性能

STUDY ON FRACTURE RESISTANCE OF RAIL WAY STEEL BRIDGE BY WELDED WIDE PLATE TEST

国内外对桥梁钢结构开展的宽板试验研究尚不多见，本文用国内常用的桥梁钢１６Ｍｎｑ、１５ＭｎＶＮｑ设计试验了５０多块宽板。通过试验比较桥梁钢结构的特点，提出了工程全面屈服准则。用这一准则分析了两种钢材及焊接接头在不同使用温度下的穿透裂纹、表面裂纹的临界长度范围。用适合于桥梁钢结构的ＣＤＤ设计曲线分析计算了两种钢材焊缝的最大容许裂纹长度，并提出了受疲劳载荷作用下桥梁钢结构缺陷评定步骤。以某大跨度铁路桥梁钢板矫形断裂事故为例。

There are a few studies on welded wide plate test for railway steel bridges in the world so for. The authors design and test more than fifty welded wide plates made of usualbridge steel l6Mnq and l5MnVNq in China. Through testing and comparing with the characteristics of railway steel bridges,the Engineering GeneraI Yielding Criterion is developed.Based on the criterion for the two steels and their welded joints,the ranges of the criticallength of the penetrating cracks and surface defects are analyzed at various service-temperatures,The maximum permissible defect size 2am of the two weldments is calculated by COD design curve adapted to the railway steel bridges,and the defect evaluation program underfatigue load has been suggested.Taking a steel plate fracture by orthopaedics in a long spanrailway steel bridge for example,the paper points out that the excessive original defect size causes brittle unstable fracture.