平面桁架结构连续倒塌动力分析方法研究

Study on the Dynamic Analysis Method of Progressive Collapse of Plane Truss Structures

平面桁架结构发生连续倒塌时造成的危害较大,为了较准确地得到结构的倒塌动力响应,研究了瞬时刚度退化法、瞬时加载法与初始条件法的适用条件。采用动力学原理推导出3种方法的动力学方程,对比关键时刻的位移,得出3种方法的异同;然后在考虑双重非线性的情况下,分别对4种桁架结构采用3种方法进行连续倒塌动力有限元分析。分析结果表明:瞬时刚度退化法能够较准确地模拟杆件失效所引起的结构动力响应,瞬时加载法与初始条件法是两种近似的方法;高敏感性杆件失效时,建议采用瞬时刚度退化法;低敏感性杆件失效时,3种方法都可以采用。

The progressive collapse of a plane truss structure can be catastrophic.In this paper,instant stiffness degradation technique,instantaneously loading method,as well as initial condition method are studied for obtaining the precise response of a structure when it collapses.The kinetic equations of the three methods mentioned above are derived with the principles of dynamics,and the comparison of the displacements at critical moments is made in order to identify the differences of these three methods.With the material nonlinearity and geometrical nonlinearity concerned,the finite element analysis on four kinds of truss structures is conducted using the three methods respectively.The results show the instant stiffness degradation technique can simulate precisely the response of structure caused by the failure member;the instantaneously loading method and initial condition method are approximately the same.When the member with high sensitivity fails,the instant stiffness degradation technique is suggested.When the member with low sensitivity fails,all three methods can be applied.