Constant-Ductility Yield Point Spectra

The theory of the performance-based seismic design (PBSD) represents the development tendency of the future earthquake-resistant design. The PBSD method is much more comprehensive, flexible and rational than the traditional method. Not only can the theory guarantee the security of human lives, but also enable a specific design according to the function of the structure as well as the realization of the user's special requirements. Displacement-based seismic design is one of the most important ways of the implemetation of the performance-based seismic design. In recently years, great attention has been paid to such method since the performance levels are more clear and the procedure is more simple. The yield point spectra (YPS), with yield displacement as its dependent variable, have been an easy and effective seismic design method which is displacement-based. A systematic study has been implemented for the yield point spectra, and the main contents are as the follows:(1)The concept of the constant-ductility YPS is introduced. Based on lots of ground motion records of four soil site conditions, the properties of the constant-ductility YPS properties have been investigated and four simplified models are given.(2)The effects of the near-fault pulse-like properties, ground motion parameters and the dynamic characteristics of the structures on the constant-ductility YPS are studied, and the qualitative analytical results are given.(3)An RC frame structure is introduced as an example to show how the YPS works in the seismic design. Besides, as a further test of the YPS method, the roof displacement and the maximum interstroy drift of the RC frame are estimated by the YPS. The feasibility and accuracy of the YPS method are displayed by comparing with the results obtained from time-history analyses.