Estimation of the seismic energy demands of two-way asymmetric-plan building systems

Abstract

This paper proposes a method for the estimation of the seismic energy demands of two-way asymmetric-plan buildings under bi-directional ground excitations. The modal absorbed energies of asymmetric-plan buildings are estimated by using the three-degree-offreedom (3DOF) modal systems. The 3DOF modal system represents the two roof translations versus the two base shears and the roof rotation versus the base torque relationships of each vibration mode of two-way asymmetric-plan buildings. Not only the total absorbed energy but also the portions of the total absorbed energy contributed from translational and rotational deformations can be respectively estimated. This study verifies the relationship between the signs of modal eccentricities and the trend of uneven distribution of modal absorbed energy on floor-plan edges of asymmetric-plan buildings. The accuracy of the proposed method was verified by analyzing one 3-storey and one 20-storey two-way asymmetric-plan buildings subjected to bi-directional ground motions. The computational efficiency of the proposed method is confirmed by comparing the computation time with that required by using the nonlinear response history analysis.Keywords Asymmetric-plan buildings · Modal response history analysis · Modal system · Absorbed energy · Torsion · Eccentricity · Seismic behavior

Understanding the trends in torsional effects in asymmetric-plan buildings

“…When the modal translations and the modal rotation are non-proportional, α xn , α zn and α θ n would not be equal. Furthermore, from previous studies (Lin and Tsai 2008, 2011, it has been found from the typical building structures that the smallest value among α xn , α zn and α θ n was usually either α xn or α zn ; and that α θ n may be in the middle or be the largest. Thus, for the purposes of discussion in this study, α xn is assumed to be the smallest among this set (Fig.…”