地震作用下空间网架结构考虑损伤累积效应的弹塑性分析

考虑钢材的损伤累积效应和应变强化效应,应用塑性应变和能量耗损理论建立了钢材的损伤力学模型;在此模型基础上,推导了网架结构考虑损伤累积效应的单元弹塑性刚度矩阵和结构动力平衡微分方程,编制了相应的有限元分析计算程序,并对一空间网架结构算例进行了数值仿真分析。结果表明,考虑损伤累积效应对空间网架结构的弹塑性地震反应有着显著的影响,其中有损伤杆件的应力减小、应变增大;无损伤杆件的应力、应变均增大;在不同方向组合地震的作用下,考虑与不考虑损伤累积效应,网架结构的内力和变形趋势相同;不同的地震作用,考虑损伤累积效应时对网架结构的内力和变形的影响也较大。

ELASTO-PLASTIC ANALYSIS OF SPATIAL TRUSSES UNDER EARTHQUAKE EXCITATIONS CONSIDERING DAMAGE ACCUMULATION EFFECT

A damage model of steel is built on the basis of the theory of plastic strain and energy dissipation, in which the damage accumulation effect and the strain strengthening effect are considered. With this model, the elasto-plastic element stiffness matrices and the structural dynamic equilibrium equations of spatial trusses are derived. The corresponding computing program of the finite element analysis is developed, and the numerical simulation of an example truss is carried out. Numerical results show that the elasto-plastic seismic responses of the spatial trusses are significantly affected by the damage accumulation effect. The stresses of the damaged rods increase and its strains decrease, but both stresses and strains of the undamaged rods increase. Under the combined excitations of the earthquakes in different directions, the variational tendency of the internal forces and deformations of the truss is the same and irrelevant to the damage accumulation effect. Under the excitations of different earthquakes, the damage accumulation effect on the internal forces and deformations of the truss is also significant.