考虑混凝土结构实际滞回性能的R-μ-T规律分析

Studies onR-μ-Tlaw of reinforced concrete structures with practical hysteretic model

单自由度体系R-μ-T规律是基于性能的抗震设计理论中的基本规律之一。以往大多研究者认为滞回模型对R-μ-T规律没有影响，但这些研究中采用的滞回模型都是理想化模型，并没有考虑实际结构的滞回性能。为了弥补R-μ-T规律研究中的这个缺陷，分别采用考虑刚度退化的两折线理想模型和考虑钢筋混凝土结构实际滞回性能的三折线模型，利用非弹性时程分析手段，计算周期从0．05-10s的单自由度体系的R-μ-T联系，分析了2种不同滞回模型对R-μ-T戒律的影响。结果表明：当采用更贴近混凝土结构实际力学特征的三折线滞回模型时，在尺相同的条件下，结构的延性需求μ有偏小的趋势；当结构自振周期较长时，采用传统的“等位移原理”是偏保守的。

R-μ-T relationship of single-degree-of-freedom （SDOF） system is one of the principal laws in performance-based anti-seismic design. In most of previous studies, it was generally concluded that the hysteretic model used in analysis has no effect on the R-μ-T law. However, the hysteretic model used in these studies is idealized and does not take into account the actual hysteretic behaviors of reinforced concrete structures. To make up this deficiency in previous studies, a series of inelastic time history analyses are conducted with two different hysteretic models, i.e., the idealized degrading bilinear model and the Takeda degrading Iri-linear model. Then the R-μ-T relationships of different SDOF systems with the fundamental period from 0.05 s to 10 s are explored, and the effects of hysteretic models on the R-μ-T relationship are investigated. The results indicated that compared with the results based on idealized degrading bilinear model, the ductility demands （μ） of SDOF systems decrease to some extent when a more practical Takeda hysteretic model is adopted, and the traditional ＂equal displacement rule＂ may be conservative for the structures with a long fundamental period.