厚壁钢桥墩的超低周疲劳裂纹萌生寿命预测

为获得厚壁钢桥墩的超低周疲劳裂纹萌生寿命,对多组厚壁钢桥墩进行数值模拟分析。采用钢材的混合强化模型预测厚壁钢桥墩在三种不同往复荷载作用下的滞回性能,并分别使用Ge模型中的局部损伤法与非局部损伤法得到不同网格尺寸下的钢桥墩超低周疲劳裂纹萌生寿命,然后使用Ge模型对厚壁钢桥墩的疲劳裂纹萌生寿命影响因素(翼缘宽厚比、试件通用长细比等)进行参数化分析。研究结果表明:混合强化模型能准确预测厚壁钢桥墩的滞回性能;Ge模型中的非局部损伤法能准确预测厚壁钢桥墩的超低周疲劳裂纹萌生寿命。最后基于裂纹萌生寿命的参数化分析结果,提出了预测钢桥墩超低周疲劳裂纹萌生寿命的经验公式。

Predicting extremely low-cycle fatigue crack initiation life of thick-walled steel bridge piers

To obtain the extremely low-cycle crack initiation life of thick-walled steel bridge piers, numerical analysis of the thick-walled steel bridge piers is carried out. The hysteretic behaviors of thick-walled steel bridge piers under three different kinds of cyclic loading patterns are predicted by using combined hardening model as constitutive law of steel. Crack initiation life of steel bridge piers corresponding to different mesh sizes is determined by using both local and non-local damage methods in Ge model. Then, some parametric studies are carried out to investigate the effect of radius-thickness ratio and slenderness ratio of the piers on crack initiation life by employing Ge model. The analytical results show that the combined hardening model of steel can accurately predict the hysteretic behavior of thick-walled steel bridge piers, and non-local damage method can be employed to accurately predict the crack initiation life of steel bridge piers. On the basis of parametric analytical results, empirical formulas for predicting the crack initiation life of steel bridge piers are proposed.