Influence of Real Ground Motion Records in Performance Assessment of RC Buildings

Reinforced concrete frame buildings with Open Ground Story (OGS) are one of the most common building configurations in urban habitat. These configurations are known to be vulnerable to seismic excitations, primarily due to the sudden loss in strength in the ground story and differential stiffness distribution throughout the structure. The differential stiffness distribution is attributed primarily to the interaction of non-structural infill wall with the moment-resisting frame. Hence, the interaction of infill wall needs to be accounted in estimating the seismic vulnerability. Therefore, the present investigation is focused on understanding the impact of utilizing real ground motion records on the performance assessment of RC buildings with and without consideration of infill walls. Fragility curves were developed for low and mid-rise structural models using Capacity Spectrum Method (CSM) specified by ATC-40 and with Incremental Dynamic Analysis (IDA). CSM uses the response spectrum specified by the respective code, unlike IDA where an ensemble of spectrum compatible real ground motion accelerograms satisfying the necessary site conditions is used in assessing the performance. Further, significant variations observed in the developed fragility curves by CSM and IDA emphasizes the sensitivity of real ground motion data in performance assessment.