Performance based seismic design of reinforced concrete symmetrical building

Abstract

One of the major developments in seismic design over the past decade has increased because of the continuing desire to limit excessive damage and maintain function of the structure after a moderate earthquake. Therefore, performance based seismic design and analysis is gaining popularity. The objective of performance-based analysis is to produce structures with predictable seismicperformance. The prediction of ductility, capacity and demand is very important to understand the seismic performance and inelastic responses of a building subjected to earthquake ground motions.The nonlinear static analysis of a G+15 reinforced concrete building is carried out in SAP2000 software. The building is subjected to six different earthquake ground motions. Two models are considered for analysis as frame with infill walls and frame without infill walls effect. Infill walls are provided throughout the building frame except the ground storey to study the open ground storey effect. The comparison is done with respect to parameters as maximum base shear, drift ratios and top storey displacement for three different performance levelsas immediate occupancy (IO), life safety (LS) and collapse prevention (CP).Analysis shows that due to open ground storey damage is localized to members in the ground storey alone, which is not captured by the bare frame analysis. Ductility requirement for frames without infill walls ishigher than for frames with infill walls. The ductility requirement increases as we move towards lower performanceobjective (i.e. from IO to CP). Inelastic displacementdemand ratio (IDDR) value for frame with infill is lower as compared to frame without infill walls. IDDR value increases from lower performance level to higher performance level. (i.e. from IO to CP). For frame without infill effect, the base shear is lower as compared with frame with infill walls and the displacement of storey is much higher for frame without infill walls as compared to frame with infill walls. The infill walls effect shows major change in the performance of building and the needs to be considered in the analysis. Performance based design technique helps to determine how the building will perform under seismic effects; well in advance. Accordingly, one can undertake suitable measures to achieve the same.