Determination of the seismic vulnerability of infilled RC buildings according to the Quadrants assessment method

Abstract

The earthquake vulnerability of the buildings has become more important after significant structural damages due to seismic events. The Quadrants assessment method is one of the effective procedures for the determination of the earthquake performance of the buildings. In this study, the impact of the infill walls on the structural vulnerability of reinforced concrete (RC) buildings was investigated using this method. Five different building models are designed such as bare RC frame, RC frame with strut infill as per field test (open ground story), RC frame with strut infill as per ASCE-41-06 (open ground story), full RC frame with strut infill as per field test (fully infilled), and full RC frame with strut infill as per ASCE-41-06 (fully infilled). All structural analyses were performed using an adaptive pushover analysis in the SeismoStruct software. The infills in the studied RC buildings were modeled as an equivalent strut as per field test or ASCE-41-06 code. The influence of different building models on the performance point, overstrength factor, response reduction factor, and ductility reduction factor was evaluated. The performance point is calculated as per the ASCE-41-06 code which is based on the “displacement coefficient method” and the application of the performance point is used to decide on the intervention/retrofit of RC structures through the “Quadrants assessment method”. In this study, the results depict that the strut width of the infill as per ASCE-41-06 is underestimated as compared to field test. Thus, the impact of the strut width is quantified on the seismic design parameters. It is concluded that there is a need for intervention/retrofit of the bare frame and open ground story RC infilled frame based on the “Quadrants assessment method” due to the absence of infills and the calculated values of the response reduction factor (R) obtained for the infilled RC building models are higher than the bare frame structure due to presence of infills.