弹性混凝土与钢组合梁的疲劳性能分析及寿命预测

Fatigue behavior analysis and life prediction of elastic concrete and steel composite beam

基于8个组合梁试件的疲劳试验结果,采用有限元计算与名义应力法相结合的方法,提出用于模拟滑移和疲劳破坏过程的精细有限元模型和计算方法.研究了混凝土中不同橡胶掺量对组合梁极限承载力、最大滑移、栓钉应力及破坏特征的影响,得到相应的应力-疲劳寿命曲线.结果表明,简支组合梁的疲劳破坏首先发生在端部栓钉,破坏过程为栓钉依次断裂.虽然疲劳断裂为脆性破坏,但组合梁在疲劳荷载作用下的整体破坏具有一定的延性.使用弹性混凝土代替普通混凝土后,组合梁的极限承载力和刚度略有降低,但延性有所提高;当橡胶掺量为5%,10%和15%时,疲劳寿命分别提高约15%,64%和125%.基于非线性数值分析得到的组合梁极限承载力和疲劳寿命与试验所测结果吻合较好,为组合梁的抗疲劳设计提供了参考.

Based on the results of fatigue experiments of eight composite beams, a fine finite element model and a calculation method applied for simulating slip and fatigue failure process are proposed by using the method combining finite element calculation with nominal stress approach. The effects of the different rubber contents in concrete on the ultimate bearing capacity, maximum slip, stress of stud and failure characteristics of composite beams are studied, and the corresponding stress-fatigue life curves are obtained. The results show that fatigue failure of simply supported composite beam first occurs at the end stud, and spreads in proper order. Although fatigue break is brittle failure, the general demolition of composite beams under fatigue loads has some ductility. After replacing normal concrete by elastic concrete, the ultimate bearing capacity and stiffness of composite beams decreases slightly while the ductility increases. The fatigue life increases by about 15%, 64% and 125% when the volumetric fractions of rubber are 5%, 10% and 15%, respectively. The ultimate bearing capac- ity and fatigue life evaluated by nonlinear numerical analysis agree well with those obtained by the fatigue tests, providing valuable references for the fatigue resistant design of composite beams.