08-10-2014, 04:40 PM
Many existing flat slab buildings may not have been designed for seismic forces. It is important to study their response under seismic conditions and to evaluate seismic retrofit schemes. Two-dimensional nonlinear push-over analysis is carried out on a typical flat slab building. The building considered is designed only for gravity loads and wind loads. Comparison with similar conventional beam-column frames shows that the flat slab buildings have low lateral stiffness, low drift capacity and have hardly an ductility, while the overstrength is of similar order. The yielding of slab in sagging is significant in flat slab buildings because of insufficient bottom reinforcement. By making the column strip bottom reinforcement continuous, the yielding in sagging can be reduced considerably, but no improvement in drift capacity is obtained. Considering all these factors it is concluded that many existing buildings in high seismic lesions may need retrofitting. The performance due to retrofitting by a) column jacketing, b) addition of beams at floor, and c) column jacketing an