Post Local Buckling Behavior and Ultimate Capacity of H–section Beam
Abstract This paper presents a study on the ultimate capacity (maximum strength and plastic deformation capacity) of a thin–walled H–section beam. An experimental study is adopted by subjecting beams under cyclic loading to a large range of deformations with large depth–thickness ratios, which are over or close to the limit value of the current standards. The objectives of the present paper are to reveal the post local buckling behavior and to propose a handy method to evaluate the ultimate capacity. Instead of the commonly used parameter of width and depth–thickness ratio, the normalized thickness ratio WF developed in this study based on the author's previous studies can be regarded as the major parameter to evaluate the ultimate capacity. The relationship between WF and ultimate capacity is examined. The improved criteria for assessing the maximum strength and plastic deformation capacity of an H–section beam is proposed using normalized thickness ratio WF and is shown to be in good agreement with the experiment results.
Experiment Study of Elasto-plastic Interactive Buckling of H-section Steel Beam-columns
Six welded H-section steel specimens subjected to the axial compressive load, the in-plane shear force and the resulting bending moment around the cross-section major axis are tested monotonically to investigate the elasto-plastic interactive buckling performances of beam-columns. The specimens are designed to fail due to local interactive buckling which is monitored by strain gauges and displacement meters. Strain curves and displacement curves varying with the shear force are illustrated, based on which the local interactive buckling is identified and the ultimate moment capacity of the specimen is extracted. The tests reveal that the local buckling of the web and flange in the compression zone occurs simultaneously resulting in the decrease of the ultimate moment capacity of the specimen. The normalized moment versus rotation curves are illustrated and compared in pairs to investigate the effects of the axial compression ratio, the flange width-thickness ratio and the web height-thickness ratio on the normalized ultimate moment capacity, which is defined as the ratio of the ultimate moment over the plastic moment. It is observed that the normalized ultimate moment capacity decreases remarkably as the axial compression ratio or the flange width-thickness ratio increases, but varies little as the web height-thickness ratio increases.
Experimental Study of Thin-Walled Steel Box Columns
An experimental investigation of the ultimate load behavior of thin‐walled box columns is reported. Small‐scale steel box column models are subjected to concentric or eccentric compressive loading and the failure brought about by local, overall, or interaction buckling. The effects of plate width‐thickness ratio and column slenderness on the ultimate load‐carrying capacity of box columns are shown to be significant. The test results were found to agree reasonably well with the theoretical predictions.