Abstract
Abstract In this paper, a numerical analysis using the finite element method, employing the commercial code Ansys, is performed to evaluate the influence of transverse stiffeners welded to the web of the steel profile on the lateral stiffness and resistant bending moment of continuous steel and concrete composite beams subjected to lateral-torsional buckling (LTB). The developed numerical model was validated by comparison with the results of tests performed by another researcher. Subsequently, a parametric analysis was carried out for beams with two and three spans, varying the spacing between the stiffeners. Finally, based on the analysis performed, it was concluded that the transverse stiffeners can significantly increase the lateral stiffness and the resistant moment of continuous composite beams. A calculation procedure to obtain this moment is proposed, having as reference the prescriptions of the Brazilian standard ABNT NBR 8800:2008.
Highlights
1.1 Lateral-torsional buckling of continuous steel and concrete composite beams The most used continuous steel and concrete composite beams are those in which the steel profile, almost always with I section, keeps its continuity on the internal supports, normally consisting of columns of the building’s structure
The Brazilian standard [2] takes as parameter twice the height of the compressed part of the web divided by its thickness for profile classification, with the upper limit for the section to be compact equal to 97. It appears that the use of Brazilian standard [2] calculation procedure to obtain the lateral-torsional buckling (LTB) resistant moment of continuous steel and concrete composite beams with transverse stiffeners, determining the rotational stiffness of the web of the steel profiles through the equation proposed by Chen and Wang [15], Equation 8 presented in this paper, leads to good results
It was observed that the placement of transverse stiffeners regularly spaced in the hogging moment region of continuous composite beams increases the resistant moment, which was already expected
Summary
1.1 Lateral-torsional buckling of continuous steel and concrete composite beams The most used continuous steel and concrete composite beams are those in which the steel profile, almost always with I section, keeps its continuity on the internal supports, normally consisting of columns of the building’s structure In these beams, the bottom flange is subjected to compression in the hogging moment region (near the internal supports) and, may suffer lateral instability, moving in the direction of the minor axis inertia of the steel profile. The bottom flange is subjected to compression in the hogging moment region (near the internal supports) and, may suffer lateral instability, moving in the direction of the minor axis inertia of the steel profile This flange is subjected to a lateral translation, δ , which is necessarily accompanied by a rotation, θ , since the web needs to bend laterally (distort) for the displacement to occur, according to Figure 1a, resulting in an ultimate limit state known as lateral-torsional buckling (LTB). It is important to emphasize that at the internal supports, the bottom flange of steel profile must be laterally constrained
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