Modelling and response of composite steel-concrete members under cyclic loading

This paper deals with the modelling and assessment of the inelastic cyclic behaviour of composite members consisting of steel beams and reinforced concrete slabs, designed to European standards. The work involves the development of detailed continuum models that can simulate the asymmetric behaviour and cyclic degradation characteristics of composite members. The generated model is first validated against available experimental results then used to investigate the influence of important parameters affecting the moment-rotation relationships at the dissipative composite beam ends under cyclic loading. Based on the results, nonlinear relationships for modelling the response of composite members are proposed. It is shown that the degradation modelling parameters are most influenced by the cross-section slenderness of the structural steel and the depth of the composite beam. Together with significant asymmetry in cyclic behaviour, around 20% higher cyclic degradation is observed in composite members compared to their bare steel counterparts. In addition to providing information required for the seismic design and assessment, the proposed expressions are utilised for the calibration of lumped plasticity models with cyclic degradation suitable for computationally efficient frame-level analysis. © 2023 The Authors. Published by Ernst & Sohn GmbH.