Seismic Performance of Nonductile Reinforced Concrete Frames with Masonry Infill Walls—II: Collapse Assessment

This paper quantifies the collapse performance of a set of masonry-infilled reinforced concrete (RC) frame buildings that are representative of 1920s-era construction in Los Angeles, California. These buildings have solid clay-brick infill walls and vary in height (2–8 stories), wall configuration (bare, partially, and fully infilled frames), and wall thickness (1–3 wythes). The buildings’ collapse behavior is assessed through dynamic analysis of nonlinear models. These models represent the walls by diagonal struts whose properties are developed from finite-element (FE) analyses, as described in the companion paper, and represent beam-columns with lumped-plasticity models. The results indicate that the presence of infill walls can increase the risk of collapse. The most collapse prone of the buildings considered are those with strong, heavy infill walls, which induce large force demands in the frame elements. The partially infilled frames, which have a soft and weak first story, also perform poorly.