Inelastic performance of steel/concrete composite members

This thesis deals with the behaviour of Partially Encased Composite (PEC) and Concrete Filled Tubes (CFT) subject to cyclic loading by means of experimental and numerical investigations. It addresses a number of design and assessment issues regarding the ductility capacity and ultimate response of PEC and CFT beam-column elements. Experimental results from ten tests including seven cyclic tests on PEC members and three cyclic tests on CFT members are presented. The set-up, instrumentation and member configuration are described followed by a full description of the experimental results. The composite members were subjected to cyclic gradually increasing lateral displacements along with varying levels of axial load simulating various gravity effects. Particular attention was given to the ultimate failure mode. To this end, in order to enhance their ductility, six of the seven PEC specimens were provided with special transverse links with the purpose of delaying the onset of local buckling. The effects of these improved details are discussed with regards to their influence on ductility as well as other structural response parameters. Numerical Finite Element models developed to simulate the response of the specimens are proposed and validated against the experimental results. This allowed for a more detailed assessment of local buckling effects in composite members. Furthermore, the FE models were used to conduct parametric studies on key design aspects related to the stiffness, capacity and ductility of composite members. Based on the experimental results and numerical studies, the implications of the finding of this work on design consideration for PEC members and CFT members are discussed