Abstract
Compared to monolithic reinforced concrete (RC) buildings, precast RC buildings are more prone to the risk of progressive collapse. Therefore, there is a need for efficient methods to strengthen beam-column joints in existing precast structures for mitigating the progressive collapse. This paper studies numerically using the finite element (FE) method the risk of progressive collapse of precast concrete beam-to-column connections rehabilitated with steel plates under middle column-loss event. Nonlinear FE models were established with the help of LS-DYNA software for predicting the response of both unstrengthened and strengthened precast RC single story two-bay frames under middle column-loss event. The developed FE models consider material nonlinearity - including strain-rate effect - for concrete, steel rebars, rubber pads and steel plates; in addition to contact behavior between different members in the joint region. The models were validated using the data of three half-scale frames tested under middle column-loss event. Specimens involved: one control unstrengthened precast RC frame, one monolithic assembly with continuous beam rebars, and another precast assembly alike the control frame but rehabilitated utilizing steel plates in joint region. The calibrated FE modeling was employed for parametric studies of practical interest wherein the influence of steel plate parameters was studied.