Seismic fragility of low ductile partially infilled reinforced concrete frame in Malaysia

Abstract

The purpose of this study is to develop analytical fragility curves for low ductile partially infilled reinforced concrete (RC) frames building under seismic ground motions. Three RC frames with their ground story open and masonry walls infilled in all of the upper stories (pilotis) comprise of three-, six- and nine-stories were selected, modelled, and analysed representing common building type in Malaysia. These frames were designed in accordance with BS 8110-1997 code specification. 45 seismic ground motions were used and subdivided into three groups namely low (L), medium (M) and high (H) records based on peak ground acceleration (PGA) over peak ground velocity (PGV) ratio. ETABS 2015 was used to perform Incremental Dynamic Collapse Analysis (IDA) with increment every 0.1g until 0.5g. The PGA was compared to the maximum inter-story drift demand obtained from nonlinear time history analysis and also to the three levels of performance-based seismic designs, namely, immediate occupancy (IO), life safety (LS), and collapse prevention (CP) to assess structural performance. The results show that as the height of structure increases, the intensity of damage decreases. Therefore, 3 story is the most damaging structure followed by 6-story and 9-story. For all types of structure assessed, the most devastating type of earthquake records is M. For 3 and 9 story, there are no difference observed between IO and LS. This shows that the preserved strength was very small where IO suddenly jumps straight to CP with increasing intensity. As for 6 story there is a clear distance between IO, LS and CP and this shows that the structure is not very fragile.