Efficacy of Code Provisions for Seismic Design of Asymmetric RC Building

The earthquake resistant design code in India, IS: 1893, has been revised in 2002 to include provisions for torsional irregularity in asymmetric buildings. In line with other international code, IS 1893: 2002 requires estimating the design eccentricity from static and accidental eccentricity. The present study attempts to evaluate the effectiveness of the design code requirements for designing torsionally irregular asymmetric buildings. Two similar asymmetric buildings designed considering and ignoring code requirement has been considered for this study. Nonlinear static and dynamic analyses are performed on these buildings to realize the difference in their behaviour and it is found that the plan asymmetry in the building makes it non-ductile even after design with code provisions. Code criterion for plan asymmetry tends to improve the strength of members but this study indicates that changing the stiffness distribution to reduce eccentricity may lead to a preferred mode of failure.