Preliminary and detailed seismic evaluation of an existing RC building in Bangladesh: a case study

As Bangladesh has experienced numerous earthquakes in previous decades, the seismic resilience of extant structures must be evaluated. In addition, the Bangladesh National Building Code (BNBC), 2020, has been updated with new seismic requirements. Consequently, it is crucial to evaluate the compatibility of the current RC buildings’ capacity with the modified seismic demand. In Bangladesh, there is no standardized method for determining the seismic vulnerability of a building. However, the Public Works Department (PWD) of Bangladesh has adopted the Japanese seismic evaluation method as the CNCRP seismic evaluation guideline for 2015. The primary objective of the study is to conduct a simplified and comprehensive evaluation of an existing RC structure in Bangladesh. The method of Hasan and Sozen (Structural Journal 94:31–39, 1997) was regarded as a simplified evaluation procedure, while the assessment technique of the Japanese seismic evaluation guideline was utilized as a comprehensive evaluation procedure. A survey of an existing RC building was conducted in order to carry out both seismic evaluations. The simplified seismic evaluation, in which column index and wall index were computed at the first story to predict the building’s vulnerability, indicated that the RC building might suffer severe earthquake damage. After this, a comprehensive seismic evaluation was conducted. According to the comprehensive evaluation method, the failure mechanism of the RC structure is assumed to be story collapse, where the columns would fail by flexure or shear contingent on the column design, and the beams are considered to be sufficiently robust. The seismic index of each floor was derived by factoring in the strength and ductility of the columns sustaining that floor in the two most important horizontal directions. BNBC (2020) computed the seismic demand index in accordance with the procedure specified in the CNCRP seismic evaluation guideline (2015). Comparing the computed seismic capacity indices and seismic demand at each story revealed that the RC building under consideration is not seismically vulnerable at any story.