Lateral-Torsional Buckling of I-Beams: Experimental Investigation

Lateral-torsional buckling behavior of simply supported universal I-beam is investigated by laboratory testing. Three point bending test was performed for three different types of cross sections with three different beam lengths for each. Load versus lateral displacement of compression flange at the mid-span was obtained for all the tested beams. Hence, three different values for experimental buckling moment capacities (i.e. buckling resistance moments) for each beam were determined by considering the required safety levels in elastic, elastic-plastic and ultimate state of the load-displacement behavior. Experimental capacities are compared with theoretical capacities which are calculated based on theoretical methods used in Eurocode 3. Experimental moment capacities were further utilized to determine experimental elastic critical moments, and corresponding coefficient which depends on the loading and end restraint conditions of the beams. The comparison shows good agreement between the buckling moment capacities. The considered three stages of experimental buckling moment capacities have a good agreement with three analytical methods given in Eurocode 3. Average value of elastic critical moment coefficient deviates 4.7% from the recommended theoretical values.