材料单轴滞回准则对组合构件非线性分析的影响

材料单轴滞回准则的选择是采用纤维模型进行组合构件非线性分析的关键问题之一。首先给出了混凝土、钢筋和钢材的精细滞回准则和简单滞回准则，以及精细滞回准则的程序实现流程，其中混凝土材料的精细滞回准则通过对已有模型的改进可准确考虑任意可能复杂加卸载路径下各类混凝土材料的强度退化和刚度退化特征。通过对组合梁和钢管混凝土柱的抗震性能试验进行模拟，验证了精细滞回准则的模拟精度。研究了材料单轴滞回准则对组合构件整体滞回性能模拟结果的影响。分析结果表明：钢材滞回准则是影响组合构件抗震性能模拟精度的关键因素，应考虑钢材的包辛格效应，而混凝土材料的滞回准则对非线性分析结果的影响很小，采用简单滞回准则即可取得较好的模拟精度。

Influence of material uniaxial hysteretic laws on nonlinear analysis of composite structural members

The selection of the material uniaxial hysteretic laws is one of the most critical issues for nonlinear analysis of composite structural members using fiber beam-column model. The refined and simple hysteretic laws of the concrete, steel bar and steel materials were first developed, and detailed programming procedures of these refined material hysteretic laws were also provided. The proposed refined concrete hysteretic law can accurately consider the strength and stiffness degradation effects under any possible complex unloading and reloading path for different kinds of concrete materials based on previous models. Then seismic tests of a composite beam and a concrete filled steel tube were conducted and the accuracy of the developed models was verified. The influence of different material hysteretic laws on the simulation results of global cyclic behavior of composite structural members was investigated. It is shown that the steel hysteretic law is the key factor influencing the analysis accuracy, and the Bauschinger effect of the steel material should be considered. The hysteretic law of the concrete material slightly influences the simulation results. As a result, even if the simple hysteretic law is adopted for the concrete material, sufficient good accuracy can be obtained.