Brace Forces in Steel Box Girders with Single Diagonal Lateral Bracing Systems
Publication: Journal of Structural Engineering
Volume 132, Issue 8
Abstract
Trapezoidal steel box girders (also known as tub girders) may be at their critical stage during construction because the noncomposite steel section must support both the wet concrete and the entire construction load. A lateral bracing system is usually installed at the top flange level to form a quasi-closed box, thereby increasing the torsional stiffness during construction. Typical lateral bracing includes a single-diagonal type (SD type) and a crossed-diagonal type (XD type). The brace forces in box girders with XD type lateral bracing systems can now be estimated with good accuracy. In some horizontally curved box girders with SD-type systems, substantial axial forces, possibly up to 35% of the total force, are developed in struts due to induced torsion and distortion, which are neglected in previous studies. In this study, analytical equations were formulated to compute the brace forces developed in bracing members by taking into account bending and torsional actions of tub girders with SD-type lateral bracing systems. Brace forces in both diagonals and struts can be estimated by these new equations more accurately than with the previous procedures. Member forces due to bending and torsion computed using the new equations were compared with those evaluated by three-dimensional finite element analyses, and excellent correlation was found.
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Acknowledgments
The work presented in this paper was supported in part by the Huff Eminent Scholar fund and Alabama Department of Transportation Project No. 930-563. These financial supports are gratefully acknowledged. The opinions and conclusions expressed or implied in this paper are those of the authors. They are not necessarily those of the funding agencies.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 132 • Issue 8 • August 2006
Pages: 1212 - 1222
Copyright
© 2006 ASCE.
History
Received: Feb 24, 2004
Accepted: Oct 5, 2005
Published online: Aug 1, 2006
Published in print: Aug 2006
Notes
Note. Associate Editor: Donald W. White
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