ST12材质焊接工字形钢支撑低周疲劳性能模拟及分析

前期的滞回性能模拟证实有限元可较精确地模拟ST12材质焊接工字形钢支撑试件表面的应力应变分布。采用基于应力应变的3种临界面损伤模型预测了支撑的低周疲劳损伤及寿命,结果表明临界面法可较精确预测裂纹开裂位置,预测结果均低于试验结果。基于临界面法的预测结果回归了寿命估算公式,并与基于试验结果的估算公式进行了比较分析,证实了影响支撑低周疲劳性能的主要因素是长细比和翼缘宽厚比。建议设计支撑时在满足"小震"不失稳的前提下,在规范允许的范围内,尽量采用具有较大长细比和较小翼缘宽厚比的支撑,以延长支撑的低周疲劳寿命。

Numerical simulation and analysis on low cycle fatigue behavior of ST12welded I-section steel bracing members

The research has demonstrated that the stress and strain distribution on the surface of the ST12 welded I-section steel bracing members gained by numerical analysis is in accordance with the true distribution. In this paper, three critical plane damage models, established based on the relationship between the strain and the low cycle fatigue life, are used to simulate the damage and predict the low cycle fatigue lives of the ST12 welded I-section bracings. The results show that, the location of the crack initiation can be predicted accurately, and the predicted lives are all less than the test ones. The empirical formulas are re- gressed and compared with the empirical formula obtained by the test results. It is verified that the main factors affecting the low cycle fatigue life are the flange width-thickness ratio b/t and the slenderness λ. Under the premise of meeting the design requirement of ＂no buckling under frequent earthquake＂ and the allowable range of standards, it is suggested that small b/t and large λ should be adopted in the brace design.