Reliability of fully assembled precast concrete frame structures against progressive collapse

Abstract

Although fully assembled precast concrete (PC) frame structures using dry connections have been widely promoted, limited studies have been carried out on anti-progressive collapse performance. This study presented a methodology to analyze and compare the reliabilities of entire structural systems between RC and fully assembled PC frame structures, which evaluates the risk and vulnerability of a structure when column failure occurs under accidental loads. First, based on the existing test results of three half-scale moment sub-structures, nonlinear finite element (FE) macro-models were established in OpenSEES software. The verified FE models were applied to three seven-story frame structures (one RC frame and two PC frames). To evaluate the progressive collapse resistance, nonlinear pushdown analysis was conducted on the frame structures using the alternate load path (ALP) approach. Combining the Nataf transformation-based point estimate method (i.e. the improved point estimate method (IPEM)) with the nonlinear analysis results, various load amplification factors (alpha(max)) were estimated. Finally, the reliability indices of the intact and damaged frame structures were calculated using the Zhao-Ono high-order moment method (HOMM). The results revealed that the fully assembled PC frames had higher failure probability (2.1-6.6%) than the RC frame (0.2%) in a catastrophic event.