Analytical Investigation on Ultimate Behaviors for Steel Heavy Clip-angle Connections Using FE Analysis

Abstract

This paper describes an analytical investigation on the strength, stiffness, and mechanical behavior of heavy clip-angle connections subjected to static loading. The work is based on the results of a large experimental investigation into the cyclic behavior of connection components incorporating with thick clip-angles. The results of these tests are described first, and then methodologies to generate the response of connection components, utilizing nonlinear finite element (FE) models with the advanced modeling methods such as the pretension force in the bolts and the interaction between two contact surfaces, are presented in this study. Numerical test results obtained from FE analyses are compared with experimental test results in an effort to verify that 3D FE models can simulate the overall and detailed behavior of a various type of clipangle connections accurately. These FE models provide useful instrumentation, which is difficult to obtain during an experiment, such as the distribution of the plastic strain, prying forces induced by the initial bolt pretension, and friction forces on the interface between a clip-angle and a steel beam. These valuable results can support the basic knowledge for developing strength models consistent with the AISC-LRFD component method of the clip-angle design. They are also utilized to better understand the parametric effect of connection components and achieve a comprehensive study of their behavior.KEY WORDS: finite element (FE) analysis; heavy clip-angle connection; tension bolts; bolt pretension; prying force. 883© 2010 ISIJ analyses are also investigated to evaluate currently accepted strength models for bolted connection designs. Prying ModelThe prediction of the ultimate strength for PR connections is a quite complex process because several yielding or failure modes interact with one another and are tied to uncertainties in both material properties and fabrication tolerances. Among the possible failure modes, the most studied cases are related to the bending action in the clip-angle leg associated with the bolt pretension. This prying mechanism can be followed by the ultimate failure of tension bolts (i.e. bolt fracture) or the yield failure of components (i.e. flange yielding). In this study, the prying action in the clip-angle leg will be addressed and the existing prying model used in the AISC-LRFD 21) will be estimated by comparing its strength predictions with FE analysis results that were calibrated to the experimental test results of steel clip-angle components. This prying model was based upon one of the most widely used models developed by Kulak et al. 22)As shown in Fig. 1(a), prying action refers to the additional forces due to the reactions at the tip of the uplifting angle leg (Q); these additional forces can increase the tension in the bolts (∑ B n ) and lead to premature failure. They effectively reduce the load applied to the clip-angle (P). The static equilibrium exists in this mechanism (∑B n ϭ PϩQ). In general, the prying force (Q) acting on the tip ...

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