Lateral Buckling Analysis of the Steel-Concrete Composite Beams in Negative Moment Region

Abstract

Distortional buckling is one of the important buckling models of steel-concrete composite beam in negative moment region. Rotation restraining rigidity and lateral restraining rigidity which steel beam web to bottom plate of steel-concrete composite are the key factors to influence the distortional buckling behavior. A comprehensive and intensive study on rotation restraining rigidity and lateral restraining rigidity which steel beam web to bottom plate of I-shaped steel-concrete composite beam in negative moment region is conducted in this paper. Energy variation principle is adopted to deduce the analytical expressions to calculate the rotation restraining rigidity and lateral restraining rigidity. Combined with the buckling theory of axial compression thin-walled bars in elastic medium, the buckling moment is obtained. Theoretical analysis shows that the rotation restraining rigidity and lateral restraining rigidity of steel beam web appear to have a linear relationship with the external loads and could also be negative. Compared with other methods, the results calculated by the proposed expressions agree well with the numerical results by ANSYS. The proposed expressions are more concise and suitable than the existing formulas for the engineering application.

Web Rotational Stiffness of Continuous Steel-Concrete Composite Castellated Beams

“…It should be noted that these code procedures apply only to composite beams without web openings. In the literature there are several studies on lateral distortional buckling (LDB) of continuous composite beams without web openings, among them Roik et al [5], Chen [6], Dekker et al [7], Hanswille et al [8], Calenzani [9], Calenzani [10], Chen and Wang [11], Ye and Chen [12], Wang [13], Guo et al [14], Zhou et al [15], Zhou et al [16], Oliveira [17], Amaral [18] Dietrich [19], Dias [20] and Oliveira [1]. The number of researches of castellated composite beams in regions of hogging moments is still limited.…”