Study On Mechanical Problems Of RC Non-planar Beam-Wall Joint

This dissertation is a part of the research project named "Analytical Models on the Out-of-plane Seismic Response of a Reinforced Concrete Wall-beam Joint" which is supported by the National Natural Science Foundation of China. The mechanical problems and equivalent analytical models of the reinforced concrete non-planar beam-wall joint were studied in this dissertation based on theoretical method.Frame-shear wall structures and frame-core wall structures are widely used in tall building structures. In such structures, there are many joints which are formed by a frame-beam connected to shear-wall in its out-of-plane direction. Compared with the coplanar beam-wall joint, the non-planar joints suffer heavily from complicated stress condition. Unfortunately, the design method and research references for the joints are lacking both in China and abroad. For most designers, the joint is idealized as a hinge joint based on the assumption that the flexural stiffness and bearing capacity in out-of-plane direction of the shear-wall are neglected. But in practical engineering cases, it is very difficult to construct a real hinge between a concrete shear wall and a beam. On the other hand, this design method will not only underestimate the stiffness of the whole structure but also result in numerous wall cracks exhibiting in the field around the joint. Such problems have aroused the attention of many researchers and engineers, and some of them have studied the problems from different aspects.The primary work of this dissertation is concentrated on the mechanical problems and equivalent analytical models of the non-planar beam-wall joint based on theory of elasticity. The main contents are listed as follows:(1) Based on elastic thin plate theory, the non-planar bending problems of the shear-wall subjected to non-planar bending moment at the joint are studied. The analytical solutions of the rotational stiffness of the joint, strain energy and internal forces (bending moment and shear force) of the wall are obtained.(2) Parametric studies for the above solutions are carried out. The primary parameters and the impacting characteristic are obtained.(3) The distribution of the strain energy and internal force of the wall subjected to non-planar bending moment is studied in detail.(4) 'Equivalent frame model' is introduced to simplify the analysis of non-planar beam-wall joint. The determination of the equivalent width of the equivalent column is obtained based on stiffness equivalence or energy equivalence. Parametric analysis and regression analysis are used to obtain simplified formulae for equivalent width.(5) The stiffening effect of the joint and different boundary conditions of the wall are studied based on finite element method (FEM). And some important conclusions are obtained.(6) Conclusions from different researchers were compared. The relations and short comings of the existing results are also pointed out.