Performance of steel moment-frame buildings designed according to the Colombian code NSR-98

A seismic performance evaluation is presented for Colombian code compliant steel moment-frame buildings of different heights (3-, 7-, and 11-stories), located in a high-risk seismic region. Seismic demand was defined by smoothed response spectra and ground motion amplitudes corresponding to various earthquake hazard levels (return periods of 75, 475 and 2475 years). Inter-story drift demands were calculated using different non-linear static methodologies and compared with results from non-linear dynamic analyses to identify the most appropriate simplified methodology for seismic performance evaluation. All drift results were analyzed with the reliability-based approach of FEMA-350 to identify the levels of confidence of the building models necessary to accomplish the damage states defined for the different hazard levels. Finally, the response modification factor (R)(R) was evaluated and found to be five times lower than that recommended by the code for a seismic design demand-level.