Estimation of storey shear of a building with Mass and Stiffness variation due to Seismic excitation

Mass and stiffness are two basic parameters to evaluate the dynamic response of a structural system under vibratory motion. High rise and multi-storeyed buildings are behaved differently depending upon the various parameters like mass-stiffness distribution, foundation types and soil conditions. 2001 Bhuj earthquake in Gujrat, India demonstrated the damage and collapse of the buildings due to the irregularities in structural stiffness and floor mass. This paper attempted to investigate the proportional distribution of lateral forces evolved through seismic action in each storey level due to changes in mass and stiffness of building. As per the BIS provisions, a multi-storey symmetrical building is considered as simplified lump mass model for the analysis with various mass and stiffness ratios. The sway pattern of multi-storeyed building under seismic excitation is taken under consideration with parabolic shape functions. The result concludes as a building structure with high mass and stiffness ratio provides instability and attracts huge storey shear. A proportionate amount of mass and stiffness distribution is advantageous to control over the storey and base shear.