Rotational Capacity of Aluminum Beams under Moment Gradient. I: Experiments

Abstract

An experimental program for evaluating the rotational capacity of aluminum beams subjected to a moment gradient loading is presented. The study focuses on local buckling and on the tensile failure susceptibility. Results are compared with design codes. Beams of different tempers, cross sections, and lengths were tested. Some beams were welded, whereas others were unwelded. Uniaxial tensile tests revealed a pronounced plastic anisotropy in the extruded beams. Tests from the reduced strength zone near welds indicate a local ultimate strength on the order of 67% of the parent material yield strength in alloy AA 6082-T6. Nevertheless, the local failure mode is ductile. The strain-hardening behavior of the material and compressive flange width-thickness ratio have a strong influence on both the moment capacity and the rotational capacity of aluminum beams. The magnitude of the moment gradient has a significant influence on rotational capacity, whereas the effect on the moment capacity is not very pronounced in the experiments. Welded members may suffer a tremendous loss of rotational capacity owing to premature tensile failure. Moreover, the tests provide a calibration basis for numerical modeling.