RESEARCH ON THE DOUBLE NONLINEAR ANALYSIS MODEL OF COMPOSITE COMPONENTS

Composite components are widely applied in super high-rise buildings. The double nonlinear behavior of composite components was analyzed by adopting three-dimensional beam element. To match the actual situation and simplify the calculation procedure, elastic tangent stiffness matrix was set up using finite element method according to the principle of minimum potential energy, in which the geometric nonlinearity is also considered; then the element section stiffness matrix was divided into elastic stiffness matrix and plastic stiffness matrix by separating section generalized strain. Subsequently, by assuming the generalized strain increment, the element plastic stiffness matrix was obtained using the fiber model method. Finally, the elastic stiffness matrix, which considers geometric nonlinearity, was combined with the plastic stiffness matrix to obtain the global stiffness matrix. The nonlinear analysis was carried out, showing that the proposed method is reasonably accurate and can be applied to nonlinear analysis of reinforced concrete members.