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Mathematical Problems in Engineering
Volume 2014, Article ID 635617, 10 pages
http://dx.doi.org/10.1155/2014/635617
Research Article

Distortional Buckling Analysis of Steel-Concrete Composite Girders in Negative Moment Area

1School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China
2School of Civil Engineering, Central South University, Changsha 410075, China
3School of Civil Engineering, University of Birmingham, Birmingham B15 2TT, UK

Received 4 July 2014; Revised 9 October 2014; Accepted 9 October 2014; Published 10 November 2014

Academic Editor: Ting-Hua Yi

Copyright © 2014 Zhou Wangbao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Distortional buckling is one of the most important buckling modes of the steel-concrete composite girder under negative moment. In this study, the equivalent lateral and torsional restraints of the bottom flange of a steel-concrete composite girder under negative moments due to variable axial forces are thoroughly investigated. The results show that there is a coupling effect between the applied forces and the lateral and torsional restraint of the bottom flange. Based on the calculation formula of lateral and torsional restraints, the critical buckling stress of I-steel-concrete composite girders and steel-concrete composite box girders under variable axial force is obtained. The critical bending moment of the steel-concrete composite girders can be further calculated. Compared to the traditional calculation methods of elastic foundation beam, the paper introduces an improved method, which considers coupling effect of the external loads and the foundation spring constraints of the bottom flange. Fifteen examples of the steel-concrete composite girders in different conditions are calculated. The calculation results show a good match between the hand calculation and the ANSYS finite element method, which validated that the analytic calculation method proposed in this paper is practical.