Rapid Seismic Assessment Method for Unreinforced Masonry Buildings in Bangladesh

Abstract

The Rapid Seismic Assessment Method (RSAM) is an inexpensive and time-efficient method for assessing the seismic vulnerability of unreinforced masonry (URM) buildings to provide timely information for decision-making on the priority of buildings that need further seismic evaluation by vulnerability scoring. The simplicity of this method and the use of visual observations make it well-suited as a first-level assessment, thus helping to determine measures that will be taken and increasing the awareness of the public to the seismic hazard effects of URM buildings. To address the need for making vulnerable structures seismically resistant in seismically prone areas, this study focuses on URM buildings. This study investigates a systematic visual assessment method as a preliminary step towards the overall seismic evaluation of URM buildings. A rapid assessment approach has been developed, specifically tailored to the construction practices and materials of the buildings. This rapid assessment technique has been designed to assist in the development of a priority list for the separate determination of URM buildings that need additional detailed seismic analysis. Through the evaluation of the seismic capacity of each load-bearing masonry wall at different levels of a building, a rapid assessment index is developed. The technique developed in this study considers some of the critical factors that affect the seismic performance of masonry buildings, such as building type, number of stories, aspect ratio, slenderness ratio of walls, opening size, irregularities, pounding effect, construction age, and the physical condition of URM structures. To make the RSAM practical and valuable, available guidelines are used, and detailed seismic analysis is performed on several URM structures for comparison of the seismic index with the analytical and finite element models. The results from the studies show that this procedure can be used as an effective and practical means for the quick assessment of many masonry buildings located in seismically active areas. RSAM can be used to prioritize URM buildings that need further detailed seismic evaluation and to optimize the use of the limited available resources. This research not only demonstrates a practical solution for the initial seismic assessment of URM buildings but also highlights the necessity of implementing measures to protect vulnerable existing URM structures. It is crucial to take appropriate actions for the safety of the public from life-threatening situations in seismically and potentially active regions.