钢桥贯通疲劳裂纹扩展行为预测方法研究  

Study of Prediction Methods for Propagation Behavior of Through Fatigue Cracks in Steel Bridge

作　　者：鞠晓臣[1] 田越[1] 潘永杰[1] 赵欣欣[1] 

机构地区：[1]中国铁道科学研究院铁道建筑研究所,北京100081

出　　处：《桥梁建设》2015年第2期53-57,共5页Bridge Construction

基　　金：一等中国博士后科学基金项目(2014M550129);中国铁路总公司重大课题项目(2013G010-A)~~

摘　　要：为研究面外弯曲作用下的贯通疲劳裂纹扩展行为,以某公铁两用钢桥的工字形横梁腹板为对象,运用公路加载的方式,对横梁腹板竖向加劲肋焊端的应力进行荷载试验,利用有限元程序ABAQUS建立横梁腹板模型,将疲劳裂纹引入模型,利用位移外推法计算裂纹前端应力强度因子,结合最大能量释放率法对疲劳裂纹的扩展行为进行预测。结果表明:腹板的面外弯曲是该部位出现疲劳开裂的主要原因;贯穿疲劳裂纹是Ⅰ型为主的混合型疲劳断裂;等效应力强度因子随着裂纹的增长先增加后减小,裂纹的扩展角度随着裂纹的增长有所增加,预测角度与实际观测到的裂纹扩展角度近似一致。因此,利用位移外推法和最大能量释放率法可有效预测钢桥疲劳裂纹扩展行为。To study the propagation behavior of the through fatigue cracks in steel bridge un‐der the action of out‐of‐plane bending , the w ebs of the I‐shape cross beams of a rail‐cum‐road steel bridge were taken as the objects and the load tests for the stress in the welded ends of the vertical stiffeners of the webs were made ,using the way of highway load applying .The finite ele‐ment program ABAQUS was used to establish the models for the webs .The fatigue cracks were introduced to the models ,the stress intensity factors of the front ends of the cracks were calculat‐ed by the displacement extrapolation method and with reference to the maximum energy release rate method ,the propagation behavior of the cracks was predicted .The results indicate that the out‐of‐plane bending of the webs is the major cause leading to the fatigue cracks in the parts of the webs .The through fatigue cracks are the mixed mode fatigue fracture mainly based on mode I crack .The equivalent stress intensity factors increase firstly and then decrease with the increase of the crack length .The crack propagation angles increase to some extent with the increase of the crack length and the predicted and actually observed crack propagation angles are approximately i‐dentical .In such case ,the displacement extrapolation method and the maximum energy release rate method can be used to effectively predict the propagation behavior of the fatigue cracks in steel bridge .

关 键 词：钢桥 加劲肋 疲劳裂纹 面外弯曲 有限元法 强度因子 断裂力学 最大释放率准则 

分 类 号：U448.36[建筑科学—桥梁与隧道工程] U441[交通运输工程—道路与铁道工程]