Towards ductility enhancement of RC structures in regions of moderate seismicity: Hong Kong case study

The reinforcement detailing of reinforced concrete frame and wall-frame structures, in regions where the probability of a seismic event is not significant, is characterized by lack of special consideration for meeting ductile response requirements. The buildings are normally designed for the onerous combination of wind and gravity loads. In the event of an earthquake on such structures, the potential for damage and consequent loss of lives may be high. Therefore, to mitigate this potential hazard, this research examined the response of representative existing structures to low to medium seismic energy excitation (PGA = 0.15g). The seismic response behaviour factors were significantly improved through the proposed risk-level-compatible detailing techniques.; The behaviour of existing reinforced concrete frame and wall-frame buildings, primarily designed and detailed for resisting onerous combination of gravity and wind loads, was computer simulated for a condition of low to moderate seismic event. It was concluded that the ductility demand on the buildings is significant and that the seismic response behaviour modification factors available in codes were not applicable for moderate seismicity consideration. Appropriate elastic seismic response behaviour modification factors were developed and presented. The vulnerability of the buildings was established through the evaluation of the theoretical displacement and curvature ductility factors demands. Experimental investigation was then performed on third scale substitute structure specimens in order to determine the available ductility factors and the proposed ductility enhancement. The specimens were specially designed to simulate the first four storeys of a building.; For reinforced concrete rigid frame structure type, two specimens were tested. One was a control specimen; reinforced in accordance with standard non seismic procedure. It was used for the verification of the available ductility factor in a frame. The other specimen was to investigate the enhancement in ductile response behaviour following modifications in reinforcement detailing specifications.; The detailing recommendations in this study eliminate the need for seismic analysis and design in ensuring frame buildings' satisfactory seismic response performance in low to moderate seismic regions. (Abstract shortened by UMI.)...