Analytical study on upgrading the seismic performance of nominally ductile RC frame structures using different rehabilitation techniques
There exist many reinforced concrete (RC) buildings that are located in seismically active zones and designed according to older strength-based codes. These buildings are susceptible to abrupt non-ductile strength deterioration once their ultimate strength is reached, which reduces the energy dissip...
| Summary: | There exist many reinforced concrete (RC) buildings that are located in seismically active zones and designed according to older strength-based codes. These buildings are susceptible to abrupt non-ductile strength deterioration once their ultimate strength is reached, which reduces the energy dissipation capacity of those buildings and results in a brittle failure. Therefore, enhancing the seismic performance of such structures is essential and should not be overlooked. Recently, performance-based seismic design methodology is being adopted by several codes, in which seismic performance is described by designating the maximum allowable damage state index for an identified seismic hazard level. Overall lateral deflection, ductility demand, and inter-storey drift are the most commonly used damage state indices. The objective of this study is to analytically investigate the effectiveness of different rehabilitation patterns in upgrading the seismic performance of existing non-ductile RC frame structures. The study investigates the performance of three RC frames (with different heights) with or without masonry infill when rehabilitated and subjected to three types of ground motion records. The heights of the RC frames represent low, medium and high-rise buildings. The ground motion records represent earthquakes with low, medium and high frequency contents. Three models were considered for the RC frames; bare frame, masonry-infilled frame with soft infill, and masonry-infilled frame with stiff infill. The studied rehabilitation patterns include (1) introducing a RC shear wall, (2) using steel bracing, (3) using diagonal FRP strips (FRP bracings) in case of masonry-infilled frames, and (4) wrapping or partially wrapping the frame members (columns and beams) using FRP confinement. The seismic performance enhancement of the studied frames is evaluated in terms of the maximum applied peak ground acceleration or velocity resisted by the frames, maximum inter-storey drift ratio, maximum storey shear to weight ratio and energy dissipation capacity. |
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