Investigations on the seismic behaviour of concrete-filled thin-walled elliptical steel tubular column: Testing and novel FE modelling

Abstract

This paper designs and tests a total of eight concrete-filled thin-walled elliptical steel tubular (CFEST) columns imposed with lateral cyclic load and axial force to acknowledge their seismic behaviour. The crucial seismic performance analyses on the failure modes, the seismic strength, the ductility index, the energy dissipation, the strength degeneration, and rigidity degeneration of the thin-walled CFEST columns are successively performed. Then a novel numerical analytical approach based on OpenSees software is developed initially by using a code programming process for the elliptical cross section. Particularly, the featured seismic properties of the CFEST column on the strength, rigidity and energy dissipation with respect to those of circular and square CFST columns are revealed. Development rules of CFEST columns’ seismic behaviour under the influence of various material and geometric parameters are investigated as well. Finally, calculation formulae for assessing the initial rigidity, peak force, peak displacement and descending rigidity of the CFEST column subjected to cyclic load are proposed. The findings indicate that the thin-walled CFEST column offers good seismic performance. Unlike the circular and square CFST columns, the outward local buckling failure of the steel tube is usually developed from the small to the large curvature regions. Under the same sectional area and steel ratio, the seismic resistance, initial rigidity, and energy dissipation of the CFEST column loaded along the major axis are much higher than those of the circular and square CFST columns, which should be fully used in engineering practice.