Vulnerability of reinforced concrete frames in low seismic region, when designed according to BS 8110

The overstrength and ductility due to redistribution of internal forces are being investigated for three bay multi-storey reinforced concrete plane fr ames, using non-linear push-over analysis. These frames are designed to res ist gravity loads, wind loads and a notional horizontal load in accordance with the British code BS 8110, which does not have any special provision fo r seismic loads. The results show that the overstrength factors for the thr ee-, six- and ten-storey frames are respectively, 7.5, 5.6 and 2.2 times th e design lateral loads, whereas, the ductility factors for the three frames are similar, and slightly greater than 2. These values yield a response mo dification factor of 18.0, 12.2 and 4.7 for the three-, six- and ten-storey frames, respectively. The effect of infill walls on the response modificat ion factor is also being investigated, and a suitable response modification factor for assessing the vulnerability of reinforced concrete frames of ab out 10 storeys high is recommended. Copyright (C) 1999 John Wiley & Sons, L td.