Seismic fragility of tall concrete wall structures in Malaysia under far-field earthquakes

Abstract

Over the years, Malaysia has encountered far-field and near-field earthquakes. Peninsular Malaysia, were affected the most by far-field earthquakes due to Sumatra fault line. On the other hand, high-rise structures are more vulnerable to far-field earthquakes compared to low-rise. Damage to the tall buildings will give a huge impact on countries financial and endangers numbers of human life. This study addresses the seismic fragility of high-rise buildings under far-field earthquake using Etabs 2017 software. The main aim of this study is to develop a seismic fragility curve of tall concrete wall structures in Malaysia. This study employs Incremental Dynamic Analysis (IDA) in order to determine the failure mechanism, inter-story drift demand, and capacity. There were two tall concrete wall structures with similar building plan and number of stories, with different number of parking level have been selected for seismic evaluation. In building 1 three stories were allocated to the parking while in building 2 it was 5 stories. The exterior and interior shear wall frame system (SWFS) at grid A and B for each building were selected. The results of the inter-story drift demand under 15 ground motions at each increment of peak ground acceleration (PGA) were used for derivation of fragility curves. Based on FEMA 356, three performance levels namely immediate occupancy (IO), life safety (LS) and collapse prevention (CP) levels were adopted. It was observed in both buildings the drift demand values increased with the increase in PGAs. The exterior SWFS have higher range of median drift demand value compared to interior SWFS. In addition, in both frame the median drift demand and PGA correlated well with each other. On the other hand, building 1 provided lower drift capacities compared to building 2. There were four fragility curves of four 2D SWFS developed from this study. Result shows that the probability of exceeding IO and CP limit state in exterior SWFS is higher than interior SWFS for both buildings. For a design PGA of 0.13g, the probability of exceeding CP limit state in building 1 was 5.6%. Although this value is considered to be small, at 0.5g the probability of significant damage rose up to 84%.