Research On The Nonlinear Property Of The Semi-Rigid End-Plate Connection At Elevated Temperature

End plate connection of steel structure about gabled frame are semirigid. There is non-linearity relationship between loading and deformation of the connection under both room temperature and high temperature, which has great influence on performance of steel structure. So it is very important to study the behavior and optimizing design method of semi-rigid connection of steel structure in fire at present.In the paper, finite element soft ANSYS is applied to analyze the non-linearity of the joints and the single span semi-rigid end-plate connection gabled frame, then the analytic results are compared. The following contents are studied in the paper.Firstly, Material properties of the different country and the organization at elevated temperature are introduced, the semi-rigid end-plate joints of the analytic model in fire are set up by ANSYS software, The moment-rotation-temperature relationship and critical temperature are obtained, Then which compare with the result of the formula in literature 27, they have a good correlation. Meanwhile, it find out that material properties at elevated temperature in EC3 is the most reasonable on the caculation of ANSYS model. Secondly, according to the loading ratio and the thickness of end-plate, the diameters of high strength bolts, the thickness of stiffeners, friction factor, the place of end-plate, the slope of the beam. The twenty four models are set up, the critical temperature of the end-plate connection and the moment-rotation-temperature curves of the connection are obtained about gabled frame by ANSYS software, deformation and Mises stress contours are obtained in joints' destroy too. Then the influences of seven parameters on the behavior of connection in fire are debated, Draw the following conclusions.The slope of the beam, the loading ratio and the place of end-plate have large effect on the manchanical behaviors of the elevated temperature about the end-plate joint of the gabled frame; If the weakest component of the joint is the end-plate and the blots,the thickness of end- plate and the diameters of high strength bolts have a certain degree effect on the joint.In order to avoid any component buckling and breaking in advance, then lead to the joint's breakage, the sizes of the joint's component must match each other, especially we pay attention to matching the end-plate's thickness, the inner flang's thickness of the column,the diameters of high strength bolts.Thirdly, the simple model is builded by ANSYS software to analyze the mechanical behaviors of integral structure about single span gabled frame, then the calculation's results by ANSYS software are analyzed. Draw the following conclusions: the connected rigidity decreases with temperature elevating,when the connected rigidity cann't restrain the beam and the column, the joint destroys suddenly;when the connection is rigid, the beam-beam's joint and the beam-column's joint is destroyed at the same time; when the connection is semi-rigid, the semi-rigid can improve the machanical property,so the beam-beam's joint is destroyed firstly, but the buckling strength of the steel decrease very fast at elevated temperature, the improvement of the connected machanical property can't increase the critical temperature about single-span gabled frame.According to the conclusions of this paper, which provide references and advices about the engineer design. At the same time, it puts forward the deficiency and limitation in the paper, and pointing out the main direction of research in the future.