SEISMIC SOIL- STRUCTURE INTERACTION IN BUILDINGS ON HILLY SLOPES

Abstract

Buildings on hills are different from the buildings in plains as they are very irregular and asymmetric. Their mass and stiffness varies along the horizontal and the vertical planes, due to which they are highly torsionally coupled. A scarcity of plain ground in hilly areas compels the construction activity on sloping ground. Many researches have been carried out on Hilly Buildings. Most of these works have been done by assuming the support of the building to be fixed. When different types of soils lie beneath the super structure instead of rocky support, the building behaves in different manner. In case of hilly buildings, highly torsionally coupled and with different soil conditions lying beneath, the Soil-Structure interaction may result in total collapse of the structure. In the present work, detailed study was carried out on two different types of building configurations, Step Back and Step Back-Set Back buildings, including a total of 16 types of buildings of varying number of storeys with only one bay in Y-direction and five buildings with varying number of bays in Y-direction, keeping constant bays in X-direction. These buildings were first analyzed by assuming the support to be fixed and also analyzed using equivalent springs representing Hard, Medium & Soft Soil. The studies were conducted for static and dynamic loads. Pushover analysis was conducted on few selected configurations. The studies highlight the inherent difference in behavior of the adopted building configuration from conventional framed structure under the action of static and dynamic loads. Further the soil-structure interaction indicates an increase in displacement and shears over the fixed base parameter. On the basis of the study the Step Back-Set Back configuration could be employed to advantage in hilly regions.