Research On The Method For Nonlinear Analysis Of R.C. Structure With Specially Shaped Columns

The reinforced concrete structure system with specially shaped columns, which possesses excellent feature of architectural function, has a broad space of application in residential structure. However, there is no mature tool and method for its nonlinear analysis at present. After thoroughly theoretical study of structure system with specially shaped columns, this paper investigates finite element method of nonlinear seismic response analysis of R.C. structure with specially shaped columns. The main work has been listed as follows:(1) According to mechanical and deformation properties of R.C. structure with specially shaped columns, the spatial multi-spring element model is established for the spatial nonlinear analysis of specially shaped columns. Taking the T-shaped column as an example, a new section displacement function is established under the hypothesis of plane cross section. Utilizing stiffness-varied link element model of three fragments and the virtual work principle, the stiffness matrix of the multi-spring element model is derived.(2) By modifying the spatial multi-spring element used to simulate specially shaped columns, a stiffness-varied spatial beam element model of three fragments with rigid region model is built. By adding a shear spring which can well accord with the shear wall mechanics behavior, the nonlinear analytical model of the spatial Multi-spring link wall element is built, of which the stiffness matrixes is also derived.(3) Applying the free style language of MATLAB, a orientation grid-coordinate method is devised for the input of complex sections information. The method that grid-numeral of matrix is associated with figure-datum of section is applied in the paper, simplifies the input and leads to a new idea for programme. The program can draw nephogram for stress or strain on the home position of section, which is convenient for the analysis of calculated results. In this way, a unified member analysis module for spatial link element is established, which simplifies the design of programme for nonlinear analysis of seismic response.(4) The nonlinear behavior of specially shaped columns and shear-wall tested in the lab is studied, and the established frame model with specially shaped columns has been conducted elastic time-history analysis. In this way, the method and the program in the paper is proved rational. And further more, the paper establishes a frame shear-wall structure model with specially shaped columns and performs nonlinear time-history analysis. Through the analysis of examples, the paper investigates the advantages and disadvantages of the models, providing some research ideas for theoretical analysis of structure with specially shaped columns and visualization program of structure.