Nonlinear finite element analysis on the steel frame with semi-rigid connections

In practice most connections of steel frames actually show semi-rigid deformation behavior that can contribute substantially to overall displacements of the structure and to the distribution of member forces. So it is very necessary that studying the behavior of these steel frames with semi-rigid connections. Considering connective, geometrical, and material nonlinear, the stiffness-matrixes equations were proposed and analysis program of steel fram considering semi-rigid conncetion, geometrical nonlinearity and material nonlinearity has been compiled in Fortran in this paper. Use this program a two-dimensional nonlinear finite element program for steel frame with semi-rigid connection was complied successfully. After the internal force and the horizontal displacement of semi-rigid connection steel frame were calculated, its bearing capacity was discussed and the analysis results were compared with the steel structure design code ones, it was used as the collapse characteristic after structural ultimate strength had lost and the appearing orders of plastic hinges and it was reasonably suggested for the design of semi-rigid connection steel frame. At last, some conclusions about effect of joint stiffness on the side sways of the vertices and on the internal force of the vertices in steel frame were obtained in this paper.