Abstract:
Past earthquakes including the Bhuj (2001) in which many concrete structures have been severely damaged or collapsed, have indicated the need for evaluating the seismic adequacy of existing buildings. In particular, the seismic rehabilitation of older concrete structures in high seismicity areas is a matter of growing concern, since structures vulnerable to damage must be identified and an acceptable level of safety must be determined. The major part of the seismic threat to human life and property comes from old buildings. Concrete buildings constructed in the past without a proper seismic design poses a serious public safety problem. In a densely populated country like India, it can cause a magnified effect on the earthquake hazard, it is really of prime importance to strengthen the seismically vulnerable structures.
In this study, an existing building which is primarily a moment resisting frame of seven storeys, has been analysed for gravity and seismic loading, and is retrofitted for seismic demand. The capacity of the existing and retrofitted building has been evaluated and compared through non-linear static analysis of the building. The local retrofitting techniques FRP jacketing has been used to strengthen the existing building and improving the overall performance behavior of the building. The enhancement in the existing member capacities has been evaluated through their strength and ductility parameters, i.e., through axial load-moment-interaction diagrams, moment-curvature diagrams and moment-rotation diagrams. The global performance of the structure has been evaluated through nonlinear static analysis of the existing and retrofitted building. The study shows that, the member ductility and strength parameters can be greatly enhanced from FRP wrapping, but their effect in the global performance of the structure is less effective; particularly in terms of enhancing the base shear carrying capacity
