Finite element analysis to predict the cyclic hysteretic behavior and failure of end-plate connections

In this paper, the development of a computer program to analyze the moment-rotation behavior of end-plate connections subjected to seismic loading is presented. A three-dimensional finite element procedure has been developed for the analysis. Only half of a symmetric section, including both the tension and compression portions of the connection have been modeled. Idealized bilinear stress-strain curves have been considered for the end-plate (A36) and bolt (A325) materials. The inelastic behavior of the materials has been modeled using incremental plasticity theory described by the von Mises yield criterion and Mroz's kinematic hardening model. The computer program developed has the capability of applying pretention loads to bolts in the connection model. It can also evaluate the boundary conditions at the back of the end-plate to account for the end-plate separation and computes the relative end-plate rotation. The program also identifies fractured elements and redistributes the strain energy from these fractured elements to the unfractured continuum before the external load is incremented. Failure of the connection is identified in the program when unstable crack growth occurs or when the connection experiences a loss in moment capacity. The results predicted by the automated analysis procedure were verified by comparison with experimental results obtained for three connection geometries in which only the end-plate thickness was varied. Based on the comparison of analytical and experimental results it was concluded that the finite element computer program gave sufficiently accurate results.