Papers by Keyword: Lateral Torsional Buckling

Abstract: Curtain wall industry is the major user of aluminium as a structural material in buildings, with two basic curtain wall systems: stick and unitised. The latter is preassembled in shops, with the main feature that frame profiles are split in two interlocking halves. Such cross sections are complex, open and prone to lateral torsional buckling. General formulas for the calculation of elastic critical moment for lateral-torsional buckling are provided in the EN 1999-1-1, with a long and complicated procedure for non-symmetrical sections which makes it pretty impractical for everyday use. The problem of such sections can also be assessed by FEM modelling, which is a time consuming and complex process. Curtain wall industry is in a need of a swift, if approximate and conservative, method for checking the risk of lateral torsional buckling of profiles with non-symmetrical cross sections. Some available analytical methods are applied on a practical example and their results compared to those obtained using FEM modelling.

Abstract: In this paper, the experimental results on the structural behaviors of the pultruded fiber reinforced plastic (PFRP) cantilevered channel beams under tip point load are presented. The dimensions of the beam specimens are 76 22 6, 102 29 6 and 152 43 10 mm. The span-to-depth ratios of the specimens are in the range of 10 to 46. A total of 36 specimens were tested to investigate the effect of unbraced length of the beam on the behavior of lateral-torsional buckling and buckling load. Then, the obtained buckling loads were compared to the critical buckling loads calculated by using the modified classical beam theory. From the tests, it was found that the beams have linear elastic responses up to 90-95% of their buckling loads. The mode of failure of the specimens is in the form of lateral-torsional buckling. The modified Timoshenko and Gere’s equation unsatisfactorily predicts the critical buckling loads of the beams. Finally, by using a curve fitting, a modification factor was proposed, and the obtained test results and those calculated by the proposed modified equation are in good agreement.

Abstract: Both total potential energy and buckling equation of two-span continuous beam with lateral elastic brace under uniform load are deduced, based on energy variation method and the principle of minimum potential energy. Buckling of H-beams is simulated by ANSYS software, then compared to theoretical value, validated its rationality. High precision buckling moment formula is regressed using 1stOpt which is a famous mathematical optimization analysis software in China. The relationship between lateral brace stiffness and buckling moment is obtained. Results: with lateral brace stiffness increases, critical bending moment of beam increases within up-limit, e.g. when lateral brace stiffness increases to certain extent, buckling moment no longer increases.