Acceleration-based ground motion intensity measures for seismic vulnerability assessment of base-isolated unreinforced masonry buildings

Base isolation is one of the most effective approaches used for seismic-resistant design of structures. The selection of suitable intensity measures (IMs) is a critical issue in the vulnerability assessment of buildings using fragility analysis. The present study aims at investigating the performance of acceleration-based IMs for seismic vulnerability assessment of base-isolated unreinforced masonry (URM) buildings using recycled rubber fibre reinforced elastomeric isolators (RR-FREIs). Five different classes of typical URM buildings in developing countries were selected and the RR-FREI base isolation systems properly designed. A number of nonlinear dynamic analyses of the fixed base (FB) and base-isolated (BI) URM buildings were then carried out using a simplified nonlinear shell element model in SAP2000. The buildings were subjected to different earthquake records, and the Latin hypercube sampling (LHS) technique was used to consider the uncertainties related to both capacity and demand. A total of six non-structure-specific, acceleration-related IMs were selected for the study, and their efficiency, practicality, proficiency, and sufficiency were evaluated. The results revealed that cumulative ground motion IMs are comparatively more effective for seismic fragility assessment of BI-URM buildings.