Nonlinear Behavior of Reinforced Concrete Shear Walls Using Macro Model

摘要

A simple macro-model for reinforced concrete shear walls has been investigated. The proposed model consists of nonlinear spring elements representing flexural and shear behavior. The flexural behavior of the model is based on the uniaxial behavior of the vertical spring elements defined according to constitutive relations for materials and the tributary area assigned to each spring element which in turn leads to the integration of important material characteristics. The shear behavior is based on a trilinear force-displacement backbone curve assigned to each horizontal spring element. The model response has been predicted using nonlinear flexural and shear spring elements of the general purpose finite element program ABAQUS6.7. The analysis results show excellent agreement with experimental measurements of slender walls. The model turned out to be capable of simulating the nonlinear behavior of the selected test specimens at different stages of loading to a very good degree of accuracy within a few seconds of CPU time. The parametric studies conducted also show that the sensitivity of the model results to different modeling parameters is not significant.In order to evaluate the advantages and deficiencies of the investigated model in comparison with the models based on the finite element approach, the nonlinear behavior of the selected test specimens has been predicted using microscopic models. Although the microscopic model could simulate some important aspects of wall behavior such as the interaction between shear and flexural response components observed even in relatively slender RC walls, distribution of cracks and stresses and local behavior, the CPU time was considerably greater than the one needed for the analysis of the investigated macro-model, and the response of the model was relatively sensitive to mesh size.Taking the CPU time and simplicity into account, the observed agreement among three lateral load-displacement curves of experimental measurements, the macroscopic and microscopic models of test specimens indicates the efficiency of the investigated macro-model.