SEISMIC SHEAR DEMANDS OF REINFORCED CONCRETE CORE WALLS

Abstract

ASCE 7-10 allows practical engineers to use Response Spectrum Analysis (RSA) procedure to compute the design forces of the structures. However, it has been found to be inappropriate for seismic shear demands of reinforced concrete (RC) walls. This thesis aims to investigate the seismic shear demands of RC core walls from low-rise to high-rise buildings. RC split core walls in 5 buildings varying from 5 to 25 stories subjected to ground motions in Bangkok and Chiang Mai of Thailand are first designed by RSA procedure in ASCE 7-10. Then, nonlinear response history analysis (NLRHA) is conducted to compute more accurate seismic demands of the structures. The results demonstrate that shear demands of core walls from NLRHA are significantly larger than those from RSA procedure. The ratio between shear force from NLRHA and RSA procedure is defined as shear amplification. The shear amplifications of core walls in cantilever-wall direction are larger than those in coupled-wall direction. The two building locations having different spectrum shapes lead to different shear amplifications. Rejec et al. (2012)’s equation can well estimate shear forces in cantilever direction of the core walls in Bangkok. Luu et al. (2014)’s equation provides good estimation of shear forces in both directions of the core walls in Chiang Mai. Beside these two equations, the shear magnification factor equation in Eurocode 8 (2004) is appropriate to be adopted to multiply with shear forces from RSA procedure before using them as design shear forces of RC core walls in both Bangkok and Chiang Mai, with the exception that it slightly underestimates the base shear forces in cantilever direction of 20- and 25-story core walls in Bangkok.