Lateral-distortional buckling of continuous steel-concrete composite beam

Abstract

In hogging bending moment regions of continuous composite beams the collapse by lateral-distortional buckling (LDB) can occur. The design against LDB according to ABNT NBR 8800:2008 begins with the determination of the elastic critical moment, which depends, among other factors, of the distribution of the bending moment in the analyzed span, taken into account in the formulation through the modification parameter Cdist. To assess the analytical formulations prescribed by ABNT NBR 8800:2008, numerical FE models that simulate the LDB behavior of continuous steel-concrete composite beams were developed in this paper. The different boundary conditions presented in ABNT NBR 8800:2008 were checked using two different models: a simplified model, with a single simply supported span; and models with multiple internal supports and more than one span. It was observed that the Cdist values prescribed by ABNT NBR 8800:2008 can be unsafe, and therefore new values for Cdist are proposed in this paper.

Resistant bending moment to lateral-torsional buckling of continuous steel and concrete composite beams with transverse stiffeners

“…In 1990, Roik et al [5] proposed an equation to obtain this moment which is still adopted by the current Brazilian standard [2], as stated in the previous subsection. Some further investigation has been made to improve the equation proposed by Roik et al [5], for example, Hanswille [9], Amaral et al [10], Dias et al [11] and Oliveira [12].…”