Seismic vulnerability assessment and retrofit of hospital building using base isolation devices

Abstract

Numerous existing hospital buildings around the world have been found vulnerable to earthquake. In this paper, the vulnerability assessment of an existing hospital building is performed, and the implementation of base-isolation (BI) device as retrofitting strategy is done. In an illustrative example, the Ancillary Building (AB) of Chittagong Medical College Hospital (CMCH), which is very important for the people of the surrounding area located in earthquake-prone region, Chittagong, is considered in this study. For the vulnerability study, firstly, preliminary assessment has been done using FEMA-310 guidelines showing that there are several non-compliance (NC) elements, which reveals the presence of structural deficiency. After that, detailed vulnerability assessment as per FEMA-310 has conducted. For detail assessment, static and dynamic analysis was done. Static analysis was performed based on the Bangladesh National Building Code-1993 (BNBC-1993) and BNBC-2006 guidelines. In addition, for dynamic analysis, 36 ground motions have been used for structural response evaluation. The result of static analysis reveals that the existing hospital building is safe for designed ground motion suggested in BNBC-1993. However, AB is not safe according to BNBC-2006. The results of dynamic analysis (linear time history and response spectrum) provide enough evidence that the existing hospital building is safe up to ground motions having PGA 0.1825 g beyond this PGA value the AB is vulnerable. For this reason, BI devices have been used as a proposed retrofitting strategy and structural performance of retrofitted AB has been investigated. The results report that the proposed retrofitting method is effective in decreasing the seismic effect on the hospital building and keeping it safe for design earthquake of PGA 0.28 g suggested in BNBC-2006.