Enhancing ductility of non-seismically designed RC wall-frame buildings

Two large-scale, two-storey, reinforced concrete shear wall-frame structures with non-seismic steel detailing and limited seismic detailing were tested under reversed cyclic loading to investigate the seismic behaviour and ductility enhancement of non-seismically designed reinforced concrete wall-frame buildings subjected to low to medium earthquakes. The inherent ductility of an ordinary reinforced concrete wall-frame was experimentally established by testing the wall-frame specimen, where the steel detailing is consistent with that typically adopted for wall-frame buildings in which the design code has not stipulated any requirement for seismic compliance in reinforcement details. An experimental investigation was then performed on the improved wall-frame specimen to investigate the enhancement of ductility capacity following modifications of the steel detailing. The modifications were simple and included the reduction of spacing of stirrups while maintaining the stirrup ratio, the provision of double-U bars at the beam–column joint, the addition of inclined bars within the beam at the support region and the arrangement of inclined distribution bars in the wall. It is concluded that ordinary reinforced concrete wall-frame buildings may not withstand low to moderate seismic events. However, the ductility of wall-frame buildings can effectively be enhanced with minor modifications in reinforcement detailing specifications, which do not result in radical changes to current design practice or in a significant increase in construction cost and difficulty.