Three-dimensional analysis on strength and deformation of concrete confined by lateral reinforcement

Abstract

The three-dimensional finite element analysis of concrete columns laterally confined by steel ties and hoops is conducted. The strength gain is numerically investigated in using the elasto-plastic and fracture model for concrete. The uniformity of the confinement stress and the damage induced are enlightened in consideration of the confinement efficiency by the discretely distributed lateral steel ties and hoops. The sectional averaged lateral stress in concrete, the minimum of which along the axis of columns governs the capacity of the entire confined columns, is found to be affected by the volumetric averaged lateral stress of concrete as well as the spacing of the tie associated with the uniformity of stress states. The authors demonstrate that the spacing of lateral ties also influences the volumetric averaged confinement of concrete, which mathematically corresponds to the axial mean value of the sectional averaged confinement stress.