Comparative study of the Dynamic Analysis of Multi-storey Irregular building with or without Base Isolator

Performance based seismic design philosophies in seismic design has become the cardinal point of interest in civil engineering structures Due to the vulnerability of Bangladesh to earthquake, base isolation system should be introduced in major earthquake zone. To see the dynamic behaviour of the structure, dynamic analysis should be performed for regular and irregular building with and without isolator. Dynamic analysis can take the form of a dynamic time history analysis or a linear response spectrum analysis. The installation of isolator in building considerably increases the time period of the structure, which means it reduces the possibility of resonance of the structure. Provision of isolator in building often increase the total cost, but as reinforcement requirement and construction material cost is reduced due to isolator. So, isolator may be incorporated at the bottom of the structure to exploit economic and structurally safe alternative. In this present study, Multi-storey irregular building of 20 stories with or without isolator has been modelled using software packages SAP2000 v15 for seismic zone of Bangladesh. Dynamic response of building under actual earthquakes, chi-chi, Taiwan, 1999 and Northridge have been investigated. This paper highlights the comparison of isolated and non-isolated building performances with Time History Analysis and Response Spectrum Analysis.