Seismic Behaviors of Steel Bar Reinforced Joints of Concrete Filled Steel Tubular Laminated Columns

Abstract

This paper presents the numerical studies on seismic behaviors of steel bar reinforced joints of Concrete Filled Steel Tubular Laminated Columns (CFSTLC). First, the material constitutive relations and modeling details are introduced. Then, the failure mode, bearing capacity and energy dissipation of CFSTLC joints under cyclic loading are studied, in which the effects of concrete grade, steel grade and reinforcement arrangement are discussed. Finally, the restoring force model is proposed to describe the seismic behaviors of bar reinforced joints. Results show that the bar reinforced joints perform good seismic performance. There are three main failure modes, including flexural failure of beam, shear failure of column and mixed failure. Increasing concrete grade and reinforcement ratio of column can increase the ultimate bearing capacity and energy dissipation capacity. Using bundled longitudinal reinforcement bars in beams can slightly reduce the ultimate bearing capacity, but can improve the energy dissipation capacity of specimens with flexural failure modes. Increasing the reinforcement ratio and steel grade can decrease the degradation rate of structural stiffness. The tri-linear restoring force model can make a good prediction of hysteretic behaviors of CFSTLC joints.