Most of the recent studies focus on the progressive collapse of ordinary structures due to gravity and blast loads. A few focus on studying progressive collapse due to seismic actions, especially of bridge structures. The past major earthquakes have shown that it is possible to develop improved earthquake-resistant design techniques for new bridges if the process of damage from initial failure to ultimate collapse and its effects on structural failure mechanisms could be analyzed and monitored. This paper presents a simulation and analysis of bridge progressive collapse behavior during seismic actions using the Applied Element Method (AEM) which can take into account the separation of structural components resulted from fracture failure and falling debris contact or impact forces. Simple, continuous, and monolithic bridges’ superstructures were numerically analyzed under the influence of the severe ground motions not considering the live loads. The parameters studied were the superstructure redundancy and the effect of severe ground motion such as Kobe, Chi-Chi, and Northridge ground motions on different bridge structural systems. The effect of reducing the reinforcement ratio on the collapse behavior of RC box girders and the variation of columns height were also studied. The results showed that monolithic bridge models with reduced reinforcement to the minimum reinforcement according to ECP 203/2018 showed a collapse behavior under the effect of severe seismic ground motions. However, changing the bridge structural system from monolithic to continuous or simple on bearing bridge models could prevent the bridge models from collapse.

中文翻译：

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地震作用导致RC箱梁桥逐渐倒塌

最近的大多数研究都集中在普通结构由于重力和爆炸载荷的作用下逐渐坍塌。一些研究重点是研究由于地震作用而引起的渐进倒塌，特别是桥梁结构。过去的大地震表明，如果可以分析和监控从初始破坏到最终坍塌的破坏过程及其对结构破坏机制的影响，则可以为新桥梁开发改进的抗震设计技术。本文使用“应用元素方法”（AEM）对桥梁在地震作用下的渐进倒塌行为进行了仿真和分析，该方法可以考虑到由断裂破坏和下落的碎石接触或冲击力引起的结构部件的分离。简单，连续，在不考虑活载的情况下，在剧烈地面运动的影响下，对整体桥梁的上部结构进行了数值分析。研究的参数是上部结构的冗余度以及严重的地震动（例如神户，Chi-Chi和Northridge地震动）对不同桥梁结构系统的影响。还研究了减小配筋率对RC箱梁的倒塌行为和柱高变化的影响。结果表明，根据ECP 203/2018将钢筋减少到最小钢筋的整体式桥梁模型在严重地震地面运动的作用下表现出坍塌行为。但是，将桥梁结构系统从整体式桥梁更改为连续式桥梁或在承重桥梁模型上将其简单更改可以防止桥梁模型崩溃。