Stability Bracing Requirements for Steel Bridge Girders with Skewed Supports
Publication: Journal of Bridge Engineering
Volume 13, Issue 2
Abstract
Cross frames and diaphragms are critical elements for the stability of I-shaped steel bridge girders during construction. The AASHTO specifications are relatively vague with regards to the stability design requirements of the braces. Spacing limits that have been used in past AASHTO specifications have been removed from the Load and Resistance Factor Design Specification, which instead requires the bracing to be designed by a rational analysis. Whereas the AASHTO specification does not define what constitutes a rational analysis, stability bracing systems must possess adequate stiffness and strength. The commercially available software packages that are typically used in bridge design generally do not have the capabilities to determine the adequacy of the bracing from a stability perspective. This paper outlines the stability bracing requirements for bridges with normal and skewed supports. The effects of support skew on the stiffness and strength requirements for stability bracing are addressed. Solutions that are available for systems with normal supports were modified to account for the effects of the support skew angle. Two orientations of the intermediate bracing were considered: parallel to the skew angles and perpendicular to the longitudinal girder axis. The solutions are presented and compared with finite-element results. The design solutions have good agreement with the finite-element solutions.
Get full access to this article
View all available purchase options and get full access to this article.
References
American Association of State Highway and Transportation Officials (AASHTO). (2002). Standard specifications for highway bridges, 17th Ed., Washington, D.C.
American Association of State Highway and Transportation Officials (AASHTO). (2004). Load and resistance factor design specification (LRFD) bridge design specifications, 3rd Ed., Washington, D.C.
American Institute of Steel Construction (AISC). (2005a). Code of standard practice for steel buildings and bridges, 13th Ed., Chicago.
American Institute of Steel Construction (AISC). (2005b). Commentary on the load and resistance design specification for structural steel buildings, 13th Ed., Chicago.
American Institute of Steel Construction (AISC). (2005c). Load and resistance design specification for structural steel buildings, 13th Ed., Chicago.
ANSYS. (2000). Finite element program users manual, Version 5.7, ANSYS, Inc., Houston.
Helwig, T. A., Frank, K. H., and Yura, J. A. (1993). “Bracing forces in diaphragms and cross frames.” Structural Stability Research Council Conf., Milwaukee, Wis.
Taylor, A. C., Jr., and Ojalvo, M. (1966). “Torsional restraint of lateral buckling.” J. Struct. Div., 92(2), 115–129.
Wang, L., and Helwig, T. A. (2005). “Critical imperfections for beam bracing systems.” J. Struct. Eng., 131(6), 933–940.
Winter, G. (1958). “Lateral bracing of columns and beams.” J. Struct. Div., 84(2), 1–22.
Yura, J. A. (2001). “Fundamentals of beam bracing.” Eng. J., American Institute of Steel Construction, 1st Quarter, 11–26.
Yura, J. A., Phillips, B. A., Raju, S., and Webb, S. (1992). “Bracing of steel beams in bridges.” Rep. No. 1239-4F, Center for Transportation Research, The Univ. of Texas at Austin, Austin, Tex.
Information & Authors
Information
Published In
Copyright
© 2008 ASCE.
History
Received: Aug 9, 2006
Accepted: Jan 16, 2007
Published online: Mar 1, 2008
Published in print: Mar 2008
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.