Nonlinear dynamic analysis of multi-base seismically isolated structures with uplift potential I: formulation

                      Panos C. Tsopelas¹, Panayiotis C. Roussis² and Michael C. Constantinou³

1. Department of Civil Engineering, University of Thessaly, Volos, Greece
2 Department of Civil and Environmental Engineering, University of Cyprus, Nicosia, Cyprus
3 Department of Civil, Structural and Environmental Engineering, University at Buffalo, State University of New York,
Buffalo, NY, USA

Abstract: The complexity of modern seismically isolated structures requires the analysis of the structural system and the
isolation system in its entirety and the ability to capture potential discontinuous phenomena such as isolator uplift and their
effects on the superstructures and the isolation hardware. In this paper, an analytical model is developed and a computational
algorithm is formulated to analyze complex seismically isolated superstructures even when undergoing highly-nonlinear
phenomena such as uplift. The computational model has the capability of modeling various types of isolation devices with
strong nonlinearities, analyzing multiple superstructures (up to five separate superstructures) on multiple bases (up to five
bases), and capturing the effects of lateral loads on bearing axial forces, including bearing uplift. The model developed herein
has been utilized to form the software platform 3D-BASIS-ME-MB, which provides the practicing engineering community
with a versatile tool for analysis and design of complex structures with modern isolation systems.

Keywords: friction-pendulum isolator, seismic isolation; nonlinear dynamic analysis; uplift; multiple superstructures; multiple bases



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