A Study On The Nonlinear Characteristic Of RC Structure With Shear Effect In Fibre Model

Many researchers pay more attention to fibre model which is a refining model for simulating nonlinear response of structural members. Research findings have proved, the model can anastomose well to actual deformation of members in biggish nonlinear deformation, and this methodological precision is higher than traditional method. However, fibre model can't simulate shear effect of structural members, in despite of it can simulate bending and axial effect and it can consider well coupling action of bending and axial effect. The modelling method with shear effect in fibre model is researched at home and overseas rarely.The modelling method with shear effect in fibre model was put forward in the thesis for simulating shear deformation of structural members. Based on the modelling method with shear effect and OpenSees which was empoldered as a nonlinear analytical tool for structures overseas latterly, several aspects were researched as emphases.Firstly, the modelling method with shear effect in fibre model was carried out in OpenSees, consequently, shear effect was come true.Secondly, based on numerical statement and regression of experimental results, the shear resilience characteristic parameters of coupling beams with small aspect ratio, short columns and shear walls were checked and corrected in practical situation of China, and the formulas for confirming parameters which adapt for the situation of China were put forward. Using seismic experimental results of several piece typical shear walls as standard points, the modelling method foregoing was checked, several conclusions were drawn: the modelling method with shear effect in fibre model based on OpenSees can simulate well shear walls' practical shear resistance and maximal displacement,and can simulate well stiffness degradation, strength degradation and rheostriction, the method has definite reliability and stability. The modelling method checked would be the theoretical foundation for latter research.Thirdly, by the modelling method with shear effect checked, nonlinear deformability of shear walls were analysed in series. Influence laws of aspect ratio, axial compression ratio, wall panel reinforcement ratio, embedded column reinforcement ratio, concrete strength and cyclic loading to nonlinear performance of shear walls were studied.Fourthly, based on the foregoing modelling method with shear effect and research conclusions reached, several conclusions can be obtained by preliminary study: the maximal centroidal axial deformation can be as a sign of ductile level, which is a function of shear resistance. Coupling action of bending and axial effect and shear effect was considered approximately by importing a set of skeleton curves of shear-shearing strain which correlates the maximal centroidal axial deformation, and sectional shear hysteretic model was expatiated, and the flow scheme of the analytical program was established.Fifthly, the analysis for a representative reinforced concrete public frame-wall in 8 region which was designed according to Chinese codes in this thesis, emphasize the nonlinear response influence law of shear effect to spatial frame-wall structures under rare earthquake action, some studies were carried out and the main conclusions can be obtained as followings:â‘ The global responses of frame-wall structures with shear effect were bigger than the ones without shear effect clearly.â‘¡The model with shear effect can reflect the practical shear resistance, shear stiffness,stiffness degradation, strength degradation, rheostriction and energy consumed situation of shear walls in reason, and the model with shear effect overrates the shear resistance, shear stiffness and the capability of energy consumed by bending of shear walls, but underestimates the capability of energy consumed by shearing.â‘¢Under rare earthquake(a=0.46g) bidirectional action, the yielding mechanism, unsubstantial tache position of spatial frame-wall structures with shear effect were the same as the ones without shear effect basically, the number of yielding members of the model with shear effect was bigger than the one without shear effect. The damage extent of members was larger than the one without shear effect, and the modelling method without shear effect underestimates ductility demand of structures and members. It was indicated that the modelling method without shear effect underestimates local responses of the spatial structures, which was adverse to seismic performance evaluating of the whole spatial structures.