Study on R - μ - T models in predicting the displacement demand of a hybrid structure

Abstract

The relationship of the strength reduction factor R, the displacement ductility μ, and the structural period T is of significance in predicting the structural demand by the method of inelastic response spectrum analysis (RSA). So far eight R - μ - T models have been proposed by researchers worldwide; however, no comparisons among them have been performed for the improvement of future models. This paper compared eight R - μ - T models from three aspects: parameters to build the models, model results under constant ductility, and response predictions for a high-rise hybrid structure with reinforced concrete core walls at the center and steel frame at the periphery. From these comparisons, it is concluded that the difference between the displacements obtained by the inelastic RSA of eight models and the elasto-plastic time history analysis is within 30%. Thus, inelastic RSA can work as an effective method in predicting the displacement demand of structures. The influence of the hysteretic model on the R - μ - T relationship is not obvious, but the site characteristics do have an effect on the results of various R - μ - T models with a maximum difference of 25%. Because no unanimous agreement has been reached regarding the effect of the damping, further research on the damping of the single-degree-of-freedom system to build the model is needed.