Three-dimensional finite elements of steel bolted connections

The three-dimensional (3D) elasto-plastic finite element method is used to study the structural behavior of the butt-type steel bolted joint. The numerical results are compared with AISC specification data. The similarity was found to be satisfactory despite the complication of stress and strain fields during the loading stages. When the steel reaches the nonlinear behavior, the bolt nominal forces obtained from the finite element analyses are almost linearly proportional to the bolt number arranged in the connection. Moreover, the bolt failure is marginally dependent on the plate thickness that dominates the magnitude of the bending effect. For the cracked plate in a bolted-joint structure, the relationship between KI and the applied load is near linear, in which the nonlinear part is only about one tenth of the total relationship. This means that the linear elastic fracture mechanics can still be applied to the bolted joint problem for the major part of the loading, even through this problem reveals highly nonlinear structural behavior.