Abstract
Tubular flange composite beams are increasingly applied in modern bridge structures. In order to investigate the overall stability behavior of doubly symmetric tubular flange composite beams with lateral bracing under concentrated load, the analysis of elastic lateral-torsional buckling is conducted by the energy variation method. The analytical solution of critical moment of doubly symmetric tubular flange composite beams with lateral bracing is obtained. Meanwhile, the simplified calculation formula of critical moment is fitted by 1stOpt software based on 26,000 groups of data, and the accuracy is verified by the finite element method. It is found that, the critical moment rises obviously with increasing lateral bracing stiffness, and adding lateral bracing to doubly symmetric tubular flange composite beams is beneficial to improve the overall stability in engineering practice. Finally, the influence of several parameters including concrete strength, span, steel ratio of flange and height-thickness ratio of web are studied. The results show that the concrete strength and the web height-thickness ratio have a weak influence on critical moment of elastic lateral-torsional buckling, while the influence of span-depth ratio and flange steel ratio is very significant.
Highlights
The tubular flange composite beam is a novel composite beam in highway bridges, which replaces flat flange of traditional I-shaped steel beam with concrete-filled steel tubular flange
Yan [11] put forward a simplified formula for calculating the flexural capacity of monosymmetric tubular flange composite beams based on the mechanical properties and failure mechanism
Zhang et al [12,13,14,15] proposed the calculation formulas of elastic and plastic flexural capacity of four kinds of monosymmetric tubular flange composite beams by the experimental and theoretical studies, and the formulas for calculating the critical moment of lateral-torsional buckling were provided based on the plate-beam theory
Summary
The tubular flange composite beam is a novel composite beam in highway bridges, which replaces flat flange of traditional I-shaped steel beam with concrete-filled steel tubular flange. Taylor [18] and Tong [19] studied the stability performance of doubly symmetric I-shaped supported steel beams with lateral bracing and proposed the analytical solution of the critical moment of the elastic lateral-torsional buckling. Zhang et al [22,23] proposed the formulas for calculating the critical moment of elastic lateral-torsional buckling of two-span doubly symmetric steel beams and I-shaped cantilever steel beams with lateral bracing by energy variation method. The effect of concrete strength, span, steel ratio of flange and height-thickness ratio of web on the elastic lateral-torsional buckling critical moment of doubly symmetric tubular flange composite beams are discussed.
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