Effect of Infill-Wall Material Types and Modeling Techniques on the Seismic Response of Reinforced Concrete Buildings

Masonry infill walls significantly contribute to the seismic demand imposed on RC buildings. However, in general, infill walls are considered as nonstructural elements in seismic design and assessment of buildings and therefore potentially lead to inaccurate prediction of seismic performance of the buildings. The modeling of masonry infill walls is challenging, especially because they exert complex nonlinear material behavior and are subject to large variation in material properties. This study investigated the effect of infill-wall material type and modeling techniques on the seismic performance of RC frame buildings. The seismic performance of 3-, 6-, and 9-story RC buildings with calcarenite masonry, clay masonry, and lightweight concrete masonry were investigated. The infill wall was modeled using macromodeling approaches in which equivalent diagonal struts were used to simulate the infill-wall behavior. Nonlinear dynamic analysis of the buildings was carried out to develop the probabilistic seismic demand model (PSDM) using 30 ground motion records. Finally, fragility curves were developed for bare frames and infilled frames to quantify the effect of the variables investigated.