Effect of Asymmetric Infills on Seismic Performance of Reinforced Concrete Frame Buildings

Unreinforced masonry (URM) infills are widely used as partitions in reinforced concrete (RC) buildings. The torsion due to asymmetric placement of infills is often unnoticed because the stiffness and strength of the infills are usually ignored during design. This study estimates the effect of asymmetric placement of infills on 8-story RC buildings designed for modern codes, older codes, and only gravity loads. Multiple stripe analysis (MSA) is done in OpenSees to assess the performance of the buildings. In addition, we compare the performance of modern code-conforming asymmetrically infilled buildings with and without an open first (i.e., no infills) story. In general, adverse effects of the infills overshadow the torsion introduced by the asymmetric layout, leading to the consistently poor performance of buildings having more infilled frames. At higher intensities of shaking, most of the eccentricity is lost due to the infill damage.