Seismic Fragility Analysis of Hollow Concrete Block Infilled Reinforced Concrete Buildings

Masonry infills are usually treated as nonstructural elements in buildings, and their interaction with the bounding frame is often ignored in analysis and design of reinforced concrete structures. The main aim of this study is to develop a seismic fragility curves showing the probability of exceeding a damage limit state for a given structure type subjected to a seismic excitation. For the purpose of this study, three distinct buildings namely, seven-story, eleven-story and sixteen-story, with typical floor plan were proposed as the case study. Each building cases are explicitly modeled as a bare frame and HCB infilled model with varying percentage of infill configurations. All building models under the case study were analyzed using Seismo-Struct software to assess seismic vulnerabilities. Non-linear dynamic time history and pushover analysis were employed to generate fragility curves. 30 generated artificial accelerograms were employed in the nonlinear dynamic time history analysis. Accordingly, for developing a fragility curve, nonlinear dynamic analyses of 30 building models for each case are conducted and the maximum roof displacement (ID) for each ground motion is recorded. Results of the study showed that bare frame has a highest probability of failure and building models with a larger percentage of infill configurations have lesser failure probability than slightly infilled building models. Basically these infills have significant contribution in arresting large lateral deflections and results in lower and most tolerable story displacements under excited earthquake motion and eventually reducing the structure’s probability of failure at life safety and collapse prevention limit states