Numerical Study Of Dynamic Responses Of Reinforced Concrete Infilled Frames Subjected To Progressive Collapse

Recently, the contribution of infill walls on progressive collapse resistance of reinforced concrete (RC) structures attracts a great many research attentions, but the research interests are mainly concentrated on the static resistance and the macro-modeling approaches, which require predefined one-dimensional load paths through two-dimensional walls. However, the load transfer paths in dynamic loading regime are still not fully understood. To this end, high-fidelity finite element (FE) models of multi-story RC infilled frames are built and validated through quasi-static experimental results. Then the FE models are used to investigate the dynamic responses of infilled frames under different single and double CRS as well as the effect of the number of stories on the load transfer paths of full-height infill walls (FHIW) and infill walls having opening (IWHO). The results indicate that the load paths along the infill walls in static and dynamic loading regimes are similar prior to the peak resistance but different in post-peak resistance for single infilled story frames. Such difference results from the loading distribution pattern, in which the static loading is typically represented by a concentrated load whereas the dynamic loading involves the uniformly distributed load. Moreover, increasing the number of infilled stories with FHIW, trans-story load paths due to composite effect always exist to enhance resistance and such paths are scenario-dependent. In comparison, the load paths for multi-story frames with IWHO are relatively scenario-independent with minor composite effect. Therefore, to generalize the macro-modeling, it is conservative to ignore the trans-story load paths.