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PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
Numerical Evaluation of Flange Thickness on the Contact Stress and Prying Action in T-Stub Steel Connections
C.A.S. Freitas, L.M. Bezerra and Y. Nagato
Department of Civil and Environmental Engineering, University of Brasília, Brazil
C.A.S. Freitas, L.M. Bezerra, Y. Nagato, "Numerical Evaluation of Flange Thickness on the Contact Stress and Prying Action in T-Stub Steel Connections", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 159, 2005. doi:10.4203/ccp.81.159
Keywords: T-stub connections, contact stresses, prying action, stresses on bolts.
This paper presents a numerical study of T-stub steel connections. Research  has shown that bolts connecting this type of connection to a support base may be under higher stresses due to a phenomenon called "prying action". This phenomenon is a result of the eccentricity between the external force and the line of resisting bolts . Depending on the flexural rigidity of the T-stub flange, additional contact forces between the T-stub flange and the support base may be developed. For very rigid flanges, no additional contact forces takes places. For flexible flanges, prying action takes places and produces additional load on the bolts. The increase of loads must be considered for a correct design of the bolts of the T-Stub connection .
Prying action effect on the bolts has been studied before but the location of the prying action forces has always been simplified. Analytical models for the design of T-stub connection, proposed by Douty and McGuire , Struik and deBack , and Nair , consider the prying action forces concentrated at a line at the edge of the T-stub flanges. Leon  shows qualitatively the distribution of the prying action forces on the contact area between the T-stub flange and the support base. A better knowledge of the contact stresses between T-stub flange and support base is helpful in understanding the appropriate location of the prying action and also the correct resistance mechanism of the T-stub connections.
This article presents a numerical investigation of the influence of the T-stub flange thickness on the prying action forces, how these forces are distributed between the T-stub flange and the support base, and the additional loading on the bolts. A 3D finite element model is used and interface elements are employed for the investigation. nonlinear finite element analyses are undertaken on connection with different flange thickness and bolt preload. Nonlinear gap elements are used as interfaces. T-stub connections with two bolts are considered with web thickness of 0.5 inch. Different T-stub flange thicknesses are employed. Discussion and conclusions on the contact areas and stresses, prying action distributions, resultant of loads on bolts, and the resistance of the T-stub connections are presented. The contact area between T-stub and support-base depends largely on the thickness of the flange. The effect of the thickness of T-stub flanges on contact areas between flanges and support base is also investigated in this paper. This paper is part of a research in progress for the numerical verification of the behaviour of T-stub steel connectors .
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