FEM ANALYSIS OF FLUSH ENDPLATE CONNECTIONS UNDER THE COMBINED EFFECT OF TENSION AND SHEAR IN FIRE

Flush endplate connections are mainly loaded by shear forces at ambient, while in fire large deformation of the beam leads to a huge catenary force within it, and connections are generally loaded to failure by combinations of tension and shear forces. A three-dimensional solid model for flush endplate connections was established by general-purpose finite element program ABAQUS. In this model, the material nonlinearity and deterioration with temperature, and large deformations were taken into consideration. The contact between the various components was explicitly modeled. The results obtained from the analysis showed a good agreement with the experimental responses. By employing the simulation model, the development of bolts section forces was obtained, and it clearly shows that the bolt shear force has negative effects on its tensile capacity. Parametric study was performed under an extensive range of load combinations of tension and shear in fire using the finite element model. The analysis results indicate that the increase of either tension or shear will reduce the failure temperature of the connection. At one specific temperature, the tensile resistance reduces linearly with the increase of shear force within the range studied. And the use of a stiff endplate can enhance both the shear and tensile resistance of a connection.