Seismic evaluation of conventional and viscoelastically damped buildings through fragility analysis

In this study, the seismic fragility based assessment of conventional and viscoelastically damped buildings was investigated. The effectiveness of viscoelastic dampers was evaluated for 5 and 12 story buildings. For the case study buildings, similar type of viscoelastic dampers was used and designed to provide the structure with two different e ? ective damping ratios of 10% and 20%. In order to exhibit the performance of conventional and viscoelastically damped framed buildings, the fragility based seismic vulnerability analyses were carried out. The buildings were designed as: a) Case 1: Conventional moment resisting frame, b) Case 2: Frame with viscoelastic dampers providing supplemental effective damping ratio of 10%, and c) Case 3: Frame with viscoelastic dampers providing supplemental effective damping ratio of 20%. Thus, a total of six different buildings were examined as a case study. Nonlinear time history analyses were performed to develop structural fragility curves and nonstructural fragility curves for drift sensitive and acceleration sensitive components. For the seismic fragility assessment, a database including 15 natural earthquake ground motion records with markedly different characteristics was used. The analysis of the results shows that depending upon the effective damping ratio, frames designed with viscoelastic dampers have noticeably lower probability of exceedance of performance limit states in comparison to conventionally designed moment resisting frame system.