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 ) was evaluated and found to be five times lower than that recommended by the code for a seismic design demand-level.