Study Of The Hysteresis Behavior Of Seismic Damaged Chs T-joints Reinforced With CFRP

In nowadays, more and more steel-tube constructions are applied in practical engineering because of its high bearing capacity, better bending and torsion stiffness, good stability and high speed of erection. The joints of the steel tube structure play the important role of load transferring,distribution forces and maintain structural integrity, but they are also the most easily damaged in earthquakes. As redevelopmenting the damaged structure or component before the post-earthquake identification is very waste and unreasonable, choosing an appropriate method to reinforce the damaged part to restore or improve its seismic ability is more economic and feasible.Pseudo-static experiments with six T-type CHS joints were used in this paper. Six T-joints were used different reinforcement forms with Carbon Fiber Reinforced Plastics (CFRP). The experiments are conducted to examine the different seismic performance of joints with different reinforcement forms. This paper presents an experimental study on the influence of different reinforcement forms with CFRP on the seismic performance of damaged joints.Six specimens were divided into two groups according to the diameter ratio of branch and chord (?). Three of them with the ? of 0.59, the other three of 0.41. In order to simulate different levels of seismic damage, three specimens of each group were applyed displacement loading of 1.32?s?1.03?s and 0.95?s respectively. ?s equals to 3% of the chord diameter as a reference of damage evaluation. The specimens with deformation of 1.32?s were reinforced with 3 layers of CFRP, the innermost fiber adhesive along the axis of the chord, the angle between the intermediate fiber and the axis of the chord is 45°, and the the angle between outermost fiber and the axis is 135°. The specimens with deformation of 1.03As were reinforced with 2 layers of CFRP,the intimal fiber adhesive along the axial of the chord and the outer adhesive along the radial. The specimens with deformation of 0.95As were also reinforced with 2 layers of CFRP, the angle between the inter fiber and the axis of the chord is 45°, and the the angle between the outer fiber and the axis is 135°. All specimens were applyed low cyclic and repeated static loading after reinforced. Analysis the hysteresis curves, skeleton curves, ductility coefficient, energy dissipation and rigidity of all specimens combine with their deformation and failure characteristics in the experiment. The result shows that, the joint reinforced with 3 layers of CFRP have the best bearing capacity, deformability, stiffness and other anti-seismic properties when ? equal to 0.59. The joint reinforced with 2 layers of CFRP which intimal fiber adhesive along the axial and the outer adhesive along the radial has the best hystersis behavior when ? equals to 0.41. So increase the layers of CFRP could improve the seismic performance when ? is bigger, and if ? is smaller, the seismic performance will improved significantly by changing the direction of the fiber, the effect of increasing the layers of CFRP is not obvious.