Modeling of opening for realistic assessment of infilled RC frame buildings

Abstract

Openings provided to meet functional requirements are often neglected in analytical assessment of Un-Reinforced Masonry (URM) infilled Reinforced Concrete (RC) frame buildings, mostly due to unavailability of simplified comprehensive model to simulate its effect. Ignoring presence of opening in infills results unrealistic assessment of seismic response for these popular building typologies, as opening reduces the strength and stiffness of the composite frame. Several reduction factor models have been developed over the years to account effect of opening in infills. In the present study efficacy of five such models of opening have been investigated which can be used by design practitioners for simulation of opening with sufficient accuracy in predicting the response of composite frame. Extensive analytical study has been conducted on a set of mid-rise and high-rise Indian infilled RC frame buildings considering various realistic combinations of openings by varying size, shape of doors and windows. The study revealed that increasing opening in infills significantly affects the seismic performance, and consequent fragility thereby reduces lateral strength, stiffness, ductility, while increasing fundamental time period, overall deformation capacity and damage probability.