Experimental behaviour and strength of concrete-encased composite beam-columns with T-shaped steel section under cyclic loading

Experimental research was conducted to investigate the structural behaviour of concrete-encased composite beam-columns with T-shaped steel section. Specimens were tested under lateral cyclic loading and axial compression. The test parameters included the distribution of longitudinal reinforcement, the spacing of transverse reinforcement, the presence of cross ties, and the axial compressive load level. The test results indicate that the cyclic behaviour and failure modes of the beam-columns are greatly affected by the direction of the bending moment owing to the unsymmetrical cross section. The concrete-encased composite beam-columns can develop stable hysteretic response and large energy absorption capacity by providing cross ties and decreased spacing of transverse ties. The current ACI and AISC-LRFD design provisions were also evaluated by comparing predicted strengths with the test results.