In order to precisely investigate an interaction between column flange and top angle's vertical leg and the effects including prying action of bolts on
M - θ
characteristics of top-and seat-angle connections, nonlinear finite element (FE)analyses for top-and seat-angle connections as one of the angle type connections were performed. In those analysis, contact model with small sliding option was applied between contacting pair surfaces of all connecting elements. Bolt pretension force was introduced in the initial step of analysis. Numerical results together with those estimated by using Kishi-Chen power model were compared with the experimental ones to examine those applicabilities.Parametric study was also performed by varying connection parameters, material properties of connection assemblages,and magnitude of bolt pretension.From this study, the following results are obtained:(1)proposed numerical analysis method can be applicable to estimate elasto-plastic nonlinear behavior of angle type connections; (2)pretension force of bolts has no effect on prying action at the initial and ultimate level of loading,but gives some effects a little at the intermediate loading level; (3)a prying action can be increased with decreasing the thickness of flange angle or increasing of gage distance from the angle heel to the centerline of bolt hole; and (4)the initial connection stiffness and ultimate moment capacity of the connections can be increased due to increasing of angle thickness, beam depth and bolt diameter,and decreasing of gage distance.