A two-step approach to progressive collapse analysis of building structures under blast loading

Structural collapse under blast loads is a very complex process. For several decades, the engineering profession has considered some approaches to analyze the essential physics of collapse phenomena. Recently, the interest in this topic has risen to an apex since the collapse of the World Trade Center towers. A two-step analysis approach to capture the characteristics of structural collapse during explosions is proposed. A numerical example is presented to illustrate the performance of the presented approach.     

地裂时桥梁倒塌过程研究

利用LS-DYNA程序建立数值分析模型，再现土耳其Arifiye大桥在1999年地震中由于地裂引起倒塌的过程，并与真实的倒塌场景进行比较，验证了分析模型的正确性。有限元分析中，墩台和上部结构均采用平面应力单元，忽略弹性支座的影响；墩台与上部结构之间采用接触算法；结构动力分析采用显式有限元法进行。从对桥梁上部结构破坏过程中梁体位移的动力响应分析可知，梁体坠落过程中没有与相邻墩台发生明显的撞击。对地裂发生位置和上部结构形式对倒塌影响的研究表明，结构完整性能够明显阻止结构发生连续性倒塌破坏；在阻止地裂引起桥梁破坏方面，连续结构形式优于简支结构形式，可有效减轻地裂发生瞬间桥梁破坏造成的生命财产损失。