1. 广西大学工程防灾与结构安全教育部重点实验室,广西,南宁 530004;2. University of Western Ontario, London, Ontario, Canada N6A 5B9
Influences of Bidirectional Seismic Excitations and P-61508; Effect on Ductility Demand
YU Bo 1 HONG HanPing 2 YANG LuFeng 1
1. Key Laboratory of Engineering Disaster Prevention and Structural Safety, China Ministry of Education,Guangxi University, Nanning, Guangxi, China, 5300042. Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario, Canada, N6A 5B9
Abstract:A new biaxial Bouc-Wen model for seismic dynamic analysis of inelastic two-degree-of-freedom (2DOF) system under bidirectional horizontal excitations was developed by adopting the normalized displacement as governing parameter and taking the P-61508;61472;effect, strength deterioration, stiffness degradation and strain hardening into account. In this model, the circular yield surface is used to describe coupling effect between orthogonal normalized restoring forces. The influences of bidirectional excitations and P-61508;61472;effect on statistical characteristics of seismic ductility demand of inelastic 2DOF system were quantitatively investigated using 69 earthquake records. Analysis results show that bidirectional excitations and P-61508;61472;effect can significantly affect seismic ductility demand of inelastic 2DOF system depending on structural parameters. The seismic ductility demand of systems with short period can be described as either the Lognormal or the Frechet distribution variable, while the Frechet distribution is preferred for systems with long period. The seismic ductility demand of inelastic 2DOF system under bidirectional excitations can be approximated by the square root of sum of square (SRSS) of seismic ductility demands of single-degree-of-freedom (SDOF) system under unidirectional excitation.