Study of the development of plastic hinges in composite steel-concrete structural members sbjected to shear and/or bending

Abstract

The accuracy of concentrated plasticity models applied in dissipative zones of composite steel-concrete beams in case of joints from Moment Resisting Frames (MRF), and in case of links from Eccentric Braced Frames (EBF) is still a matter of discussions. To simplify the problem, a quite current practice, is to not install connectors in the expected plastic zones, and to consider having symmetric moment or shearing plastic hinges, which occurs in the steel beam or link only. However, since the reinforcing bars still remain active, even if the connectors have been suppressed , and also due to some friction contact between concrete slab and beam or link flange the assumption of the “nominal ”symmetric” plastic hinge could be false. Intensive experimental research on composite beam-to-column MR joints and portal EBFs, accompanied by advanced numerical simulations were carried out in the CEMSIG Research Centre (http://cemsig.ct.upt.ro) of PU Timisoara in order to check the validity of this assumption. Reference single steel specimens and then composite ones, with and without headed connectors, have been tested under monotonic and cyclic loading. Based on test results and accompanied by numerical simulation, potential multi-linear models for time-history analyses are suggested and discussed. The thesis summarizes the experimental and numerical investigation and presents the main conclusions of the research.