Structural pounding of three adjacent multi degree of freedom system under subsurface blast and seismic action by considering and ignoring the effect of soil structure interaction

Abstract

A lack of spacing between the adjacent structures is mostly observed in metropolitan cities due to more land cost, which has led to more serious problem called as structural pounding in many recent earthquakes. Large impact forces and short acceleration pulses are mostly noticed during the structural pounding, and which is hazardous to structural health of the buildings involved in this phenomena. In the present paper three adjacent multi-degree-of-freedom linear elastic systems subjected to seismic and subsurface blast actions are analyzed by considering and ignoring the effect of soil structure interactions. Three dimensional buildings are analyzed and designed for deciding the column and beam sizes in SAP 2000 NL software considering all possible load combinations of dead load, live load and earthquake load as per IS 1893:2016 Part I. The subsurface indirect method is used for studying the effect of soil structure interaction. The SSI spring stiffness’s and damping constants are calculated as per FEMA 356. These buildings are converted into the lumped mass model as per the principles of dynamics of structures. The entire analysis of three adjacent lumped mass models with insufficient separation is carried out in time domain form using MATLAB programming. The outputs are measured in the forms of top storey displacement time history plots, top floor level pounding force time history plots and base shear force time history plots. From the outputs, it is noticed that the SSI amplifies the displacement response of building than that of fixed base system. SSI also overrates the pounding response of structure. Blast force response is much smoothens than seismic response of structure.