厚边U肋钢桥面顶板与纵肋焊缝疲劳裂纹扩展模式与验算曲线研究  

Studies on Fatigue Crack Propagation Pattern and Design S-N Curves of Rib-to-deck Welded Joints in Orthotropic Steel Decks Using Thickened Edge U-ribs

作　　者：冯霄暘 郑凯锋[1] 衡俊霖 雷鸣 张宇[1] FENG Xiaoyang;ZHENG Kaifeng;HENG Junlin;LEI Ming;ZHANG Yu(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031

出　　处：《铁道学报》2021年第4期191-199,共9页Journal of the China Railway Society

基　　金：国家自然科学基金(51778536)。

摘　　要：前期研究表明,应用厚边U肋的正交异性钢桥面能够有效改善顶板与U肋连接焊缝的疲劳性能。在此基础上,开展了2组共7个局部足尺模型疲劳试验,在获取S-N基础数据的同时,对疲劳裂纹萌生、汇聚和扩展进行监测并对裂纹断面进行详细分析。结果表明:疲劳裂纹首先在顶板与U肋焊缝长度方向以多处点裂源形式萌生,其后沿纵向和板厚方向扩展并汇聚形成微小可见裂纹;微小可见裂纹以较高速率沿纵向和板厚方向扩展,最终形成贯穿裂纹引起疲劳失效。值得注意的是,在疲劳裂纹萌生与扩展阶段,其形态逐渐由初始多处半圆状点裂源过渡为半椭圆状可见裂纹。此外,基于试验数据推导出具有95%保证率的厚边U肋钢桥面顶板与纵肋焊缝S-N验算曲线,以供工程设计使用。Earlier studies have suggested that the fatigue performance of rib-to-deck(RD)welded joints in orthotropic steel decks(OSDs)can be effectively improved with thickened edge U-ribs(TEU).On this basis,two groups of seven local full-scale model fatigue tests were carried out.During the tests,along with acquisition of basic S-N data,the fatigue crack was monitored with respect to its initiation,coalescence and propagation.In addition,a detailed analysis was conducted using the fractography.The results reveal that fatigue cracks first initiate in the form of multiple point cracking sources along the RD joint,and then propagate in both the longitudinal direction and thickness of the steel plate until they coalesce into visible small cracks.Once the visible cracks are formed,they will grow along the longitudinal direction and the thickness of the plate at a relatively high rate before finally forming through cracks that cause the fatigue failure.It is worth noting that,during the initiation and propagation of fatigue cracks,their shapes gradually transform from the initial semi-circular point cracking sources to semi-elliptical visible cracks.Besides,based on the test data,the design S-N curve with the survival rate of 95%has been derived for RD joints in OSDs using TEUs,which can be used in the engineering design.

关 键 词：正交异性钢桥面 厚边U肋 裂纹扩展 点裂源 微小可见裂纹 疲劳验算曲线 

分 类 号：U441.4[建筑科学—桥梁与隧道工程]