Elastic-Plastic Analysis of Bolted Angles Usable in Steel Frame Connections

Abstract

An analytical model was proposed to predict the monotonic load-deformation behavior of bolted angles used in semirigid steel frame connections. This model was validated using the results of 30 pull tests performed on bolted angle specimens with 10 different geometrical configurations. The model employed elastic-plastic analysis to follow the behavior upon formation of up to four plastic hinges involved in the entire yielding mechanism. The presented model is capable of handling slip in the column-leg bolts, which occurs when the developed shear force exceeds the frictional resistance. It was shown that the inclusion of slip in the column leg affects the elastic-plastic response, especially for stocky angles, and should be taken into account. The method also included strain hardening and geometrical nonlinearity (truss action). The ultimate deformation of the angle at fracture was also predicted through the kinematics of the mechanism using the ultimate strain criteria. The comparison of the test and analytical results showed the proposed method provides a reasonable backbone curve for the angle behavior, which is usable to make nonlinear spring element models for semirigid connections composed of flange angles.