基于有限质点法的结构倒塌破坏研究Ⅱ:关键问题与数值算例

Structural collapse analysis based on finite particle methodⅡ: key problems and numerical examples

采用有限质点法求解结构倒塌破坏的关键问题,包括结构动力反应、几何非线性和材料非线性分析以及构件断裂。采用虚拟运动分离单元的刚体运动和纯变形,用以模拟结构的几何非线性行为;根据不同的本构模型计算质点内力,求解材料非线性问题;为模拟构件的断裂,建立了杆单元和梁单元的断裂准则,提出了断裂发生后的结构计算方法;综合考虑各关键问题,给出结构倒塌过程模拟的分析流程。通过对一个空间刚架的几何非线性、材料非线性和断裂行为的模拟和分析,验证了有限质点法在结构复杂行为计算中的正确性;最后对某悬挑网架结构在台风作用下的倒塌破坏过程进行研究,并将分析结果与现场破坏情况进行对比和分析。研究表明,该方法适用于结构的倒塌破坏研究,可以对倒塌全过程进行模拟,计算结果能够揭示结构的倒塌破坏机理。

Based on the finite particle method（FPM）,this paper proposes how to deal with key problems of structural collapse analysis,including the dynamic response,geometric and material nonlinearities,and member fracture.To solve the geometrical nonlinear problem,fictitious motion is used to separate the rigid body motion from the pure deformation of the element.According to different constitutive models,the internal forces of particles were calculated to solve material nonlinear problems.To simulate the member fracture,the failure criteria of the bar and beam element were built,followed by the method to analyze the structural behavior after fracture happens.The flowchart of the collapse analysis by the FPM was presented with consideration of the above mentioned key problems.The geometrical,material nonlinear behavior and member fracture of a framed structure were simulated and analyzed.The validity of the FPM for the analysis of the complicated structural behavior was proved.The collapse process of a practical cantilever space truss was then simulated and analyzed.Comparing with the practical failure mode,further information of the collapse mechanism was obtained.The FPM proposed in this paper is applicable for structural collapse analysis,which can simulate the whole collapse process and analyze the failure mechanism.