HIGH STRENGTH CONCRETE COMPOSITE COLUMNS SUBJECTED TO AXIAL AND CYCLIC FLEXURAL LOADING

An experimental investigation is undertaken to assess the seismic performance of high strength concrete (HSC) composite columns subjected to combined axial and cyclic lateral loading conditions. Current European design rules (Eurocode 8) require a concrete strength class between C20/25 - C40/50 N/mm(2) to be specified in dissipative zones of a composite structure. The aim of the research presented in this paper is to determine the conditions for which HSC (f(ck) > 40N/mm(2)) composite columns can be used in earthquake-resistant moment-resisting frames. This experimental programme is supported by the development of a numerical model based on Mander's stress-strain model. The model incorporates the influence of varying concrete confinement, axial load and P-Delta effects to effectively determine the moment-displacement response of the composite section and the associated axial strain demands. The model is validated against the experimental data and it is shown to display good correlation with the results of the HSC experimental programme.