Assessment of the Failure Mechanisms of URM Infilled RC Hill Buildings

There is an ever-increasing demand for constructible land in the cities and towns of the Indian Himalayan region owing to the rapidly rising population in the country. Due to the scarcity of flat lands, buildings in this region are mostly constructed on sloping terrain with foundations at different levels. These types of structural configurations adversely affect the seismic performance of the buildings in a region where the seismicity is generally extremely high. The problem is further complicated by the fact that proper earthquake resistant design guidelines as per Indian Standards are unavailable for buildings constructed in hilly terrain. The seismic response of such buildings varies depending on the type of structural configuration and gets complicated when we consider the complex interaction between frame and Un-Reinforced Masonry (URM) infills. The aim of the manuscript is to achieve a comprehensive understanding of URM infilled Reinforced Concrete (RC) hill buildings considering various structural configurations that are common in hilly region. Towards this purpose, an analytical study has been undertaken on a set of URM infilled RC buildings having the most commonly found structural configurations in hilly region. Seismic response is evaluated with the help of non-linear time history analyses. It has been observed that the response parameters in terms of Inter-storey Drift Ratio (IDR) and roof acceleration were higher for buildings with setbacks in the structural configuration. Consequently, the extent of damage probability is also higher for setback buildings. It has also been observed that collapse of all the considered buildings is caused predominantly by shear failure of short columns.