Indices for assessing seismic vulnerability of buildings based on linear and non-linear static analyses

The present paper proposes indices for assessing seismic vulnerability of multi-storeyed reinforced concrete buildings with moment resisting frames based on the equivalent static analysis and push-over analysis. Based on the push-over analysis, indices for the lateral load resistance of a building, drift of a building, overall performance of the beams and columns (referred to as members), performance of the columns in individual storeys are proposed. Based on the equivalent static analysis, an index for the storey drifts, an overall index for the demand-to-capacity ratios of the members and an index for the demand-to-capacity ratios of the columns in individual storeys are proposed. The purpose of the indices is to have quantitative and objective measures of the observations from the analyses, which otherwise remain subjective. The indices can be used to compare alternative retrofit schemes. A case study is reported to demonstrate the applicability of each index. From the results it can be concluded that the indices indeed reflect the deficiencies as per the respective analysis. From a push-over analysis, an index can detect a soft storey mechanism and other indices can check the lateral load resistance and drift of the building based on the required performance level. If a pushover analysis cannot be performed, indices based on the equivalent static analysis can detect the high demand in the columns of an open ground storey, and check the storey drifts.