Research On The Nonlinear Analysis And Nonlinear Behaviors Of Shear Wall And Core Walls With Concealed Bracings

It is well known that the RC wall is a kind of horizontal load resistant systems. It is widely used in tall building for its good seismic performance. In the recent years how to improve the seismic behavior of the shear wall is a hot topic in the field of seismic design. Professor Cao Wanlin (Beijing University of Technology) proposed a kind of RC shear wall with concealed bracing. The experiment results show that the setting of concealed bracings in the shear wall is able to improve seismic behaviors of the shear wall obviously. But it also is insufficient in the theoretical research aspect of this new structure. The RC shear wall with concealed bracing is computed based on the element of concrete with dispersed reinforcement. This element is unable to reflect concealed bracing's contribution to energy dissipation of the shear wall. In this paper, theoretical analysis and design method research have been finished. In the paper, main contents and outcomes are listed as follow:Firstly, the software ANSYS is adopted to establish the elastic- plastic finite element analysis model for the RC shear wall. In this model, the element SOLID65 is used for simulating reinforced concrete, and the element PIPE20 is used for simulating concealed bracings. The discrete crack model is adopted to simulate concrete crack. The bilinear elastic-plastic model is adopted to simulate the stress-strain relationship of steel. The comparison between the calculational results and the test indicates that the ANSYS can be success to analyse RC shear wall.Secondly, using ANSYS, the nonlinear analysis of RC low-rise shear wall with concealed bracing and coupled shear wall with concealed bracing have been finished, the global stiffness and its attenuation process, bearing capacity, ductility, energy dissipation and failure feature of structures have been presented. It is shown that the crossed reinforcing bars and concealed columns improve the seismic performance of RC shear wall. The mechanisms of RC shear wall working together with concealed bracing are also presented.Thirdly, reinforced concrete core walls with concealed bracings is put forward based on the study of RC shear wall with concealed bracings. Through the comparison between the computing result of the reinforced concrete core walls and the results of the reinforced concrete core walls with concealed bracings under the horizontal loading, the effects of concealed bracings on the bearing capacity, stiffness, energy dissipation and failure phenomena of reinforced concrete core walls are discussed. The results show that concealed bracings are able to improve greatly the seismic behavior of reinforced concrete core walls.Finally, a lot of comparative analysis have been carried out. The influences of different concealed bracings form and different concealed bracings reinforcement ratio on the bearing capacity, ductility and energy dissipation of the Shear Wall and core walls are discussed. Moreover, some suggestions of design parameter selection is proposed.