Low cycle fracture behavior of steel members with circular hollow section subjected to eccentric load

This study aims to investigate the effect of eccentric load on the seismic and fracture behavior of Q235B steel members with circular hollow section (CHS). To this end, uniaxial tension and ultra-low cycle fatigue tests on both un-notched and notched Q235B steel coupon specimens were conducted first to evaluate the material's micromechanical fracture behavior. Next, 7 full-scale Q235B CHS steel members with different global slenderness were tested under cyclic axial loads with varying eccentricities. It is observed that: (1) the increase of the eccentricity of the axial load negatively affects the seismic and fracture resistance of CHS steel members, resulting in the deterioration of the strength, stiffness, energy dissipation, and ductility; (2) Large eccentricities lead to the reduction in the fracture life of Q235B CHS steel members; and (3) High global slenderness results in the reduction in both compression bearing capacity and energy dissipation of CHS steel members. In addition to the experimental program, finite element analyses are performed to simulate the seismic and fracture behavior of CHS steel members. The results from the finite element analyses are in good agreement with those from the experiment.