LAUSR

One kind of the irregularities in structures, with considerable effect on seismic performance, is setback in elevation that causes large damage especially in the vicinity of the irregularity. The main objective of this research is to propose and develop drift-based index to estimate damage to reinforced concrete moment resisting frames with setback. For this purpose, first, inelastic dynamic time-history analysis is performed on several frames with different types of setbacks subjected to various earthquake records and damage to them is computed by the Park–Ang damage index. Then, the two relations between the damage and drift are derived by applying irregularity indices to account for setback effects. It is shown that the proposed damage indices are capable to estimate the damage index of setback frames.