建筑结构钢超低周疲劳断裂破坏的损伤预测模型

A DAMAGE PREDICTION MODEL FOR ULTRA LOW CYCLE FATIGUE FAILURE OF BUILDING STRUCTURAL STEEL

针对地震作用下建筑结构钢的超低周疲劳断裂问题,在单调加载损伤模型的基础上,提出了一种适用于超低周循环加载情况下的损伤预测模型,并借助ABAQUS软件的用户自定义材料子程序模块,将建立的损伤预测模型引入到有限元分析程序中。然后分别依据建筑钢结构母材、热影响区和焊缝金属缺口试样的单调加载和超低周循环加载试验,标定了材料的损伤模型参数,并对比分析了缺口圆棒试样在不同加载方式下的损伤演化规律,损伤分析结果表明缺口圆棒试样的裂纹都产生于试样截面中心处,这与试验结果一致。最后,以钢框架梁柱焊接节点为研究对象,应用损伤模型分析了节点危险部位的损伤演化规律,数值模拟了节点的超低周疲劳断裂破坏过程,最终得到节点的疲劳寿命与试验结果吻合良好。

Based on the damage model under a monotonic loading condition, a new damage model is developed to predict the ultra low cycle fatigue failure of building structural steel subjected to seismic actions. The damage prediction model was implemented in commercial finite element software ABAQUS by using the user material subroutine. Then, parameters used in the damage model of building structural steel base metal, heat affected zone and weld metal were calibrated respectively through monotonic loading tests and ultra low cyclic loading tests of notched coupon specimens, in addition, the damage evolution laws at the center of notched specimen under different loading conditions were compared. It can be observed from the comparison that crack always initiates in the center of specimens, which is consisted with the test results. Finally, the damage model were applied to investigate the damage evolution of beam to column welded joints under ultra low cyclic loading history. The fracture process was simulated and the number of cycles to fracture was predicted, which agrees well with the experimental results.