主梁新细节的疲劳寿命预测及参数分析

为研究沪通铁路长江大桥主梁新细节的过焊孔半径、过焊孔形状、焊脚尺寸对大桥疲劳性能的影响,采用热点应力法预测疲劳寿命,并将其与9个试件的疲劳实验结果进行比较,在此基础上建立有限元模型进行相关参数分析.研究表明:基于热点应力法预测的主梁新细节的疲劳寿命与试验测试值存在一定差异,但均小于15%;主梁新细节过焊孔附近的翼缘板网格尺寸对其热点应力影响较小,小于1.6%,对此焊接细节采用两点外推法与三点外推法计算热点应力均是可行的;焊脚尺寸、过焊孔半径对热点应力、翼缘板的最大应力有一定的影响,但变化幅度均不超过10%;热点应力、腹板、翼缘板最大应力受长短半轴比的影响显著,腹板最大应力的变化幅度达21.6%,而其他两者均未超过10%.建议在有条件时可采用椭圆形过焊孔的焊接细节,且长短轴之比适当取大些. 

Fatigue Life Prediction and Parameter Analysis of Girder New Detail

In order to study the influence of the cope hole radius, shape and fillet weld size of the new detail of Hutong Railway Yangtze River Bridge girder on fatigue performance, the hot spot stress method was used to predict fatigue life, and the calculation results were compared with the experiment results of 9 welded specimens,then parameter analysis based on finite element models was conducted. The results show that:a little difference exists between fatigue life predicted by hot spot stress method and the results of fatigue experiments, which is within 15%; the mesh size of flange plate near the cope hole had little impact for hot spot stress, which is within 1.6%, two-point and three-point extrapolation method are feasible for this new detail; the fillet weld size and the cope hole radius have some influence on the maximum stress of flange plate and hot spot stress, the variation range is within 10%; the ratio of major and minor axes has a significant impact on the maximum stress of flange plate and web and hot spot stress,the variation range of web is 21.6%, however, the others are not beyond 10%. It is suggested that the welded detail with elliptical the cope hole can be used if the condition allowed, and large ratio of major and minor axes should be selected.