Hysteretic Performance Analysis Of The Pre-Pressed Spring Self-Centering Cable Brace(PS-SCCB)

In recent years,with the continuous improvement of the seismic resistant technology globally,the number of building collapses and casualties caused by earthquakes has dropped significantly,which indicates that modern seismic design methods have basically achieved the goal of collapse prevention.However,the traditional seismic-resisting structural systems mostly adopt the ductile structure,which tends to produce large residual deformation after the earthquake,not only leading to the interruption of the building function,but also bringing great difficulties to the post-earthquake repair,causing high economic cost and time cost.For this reason,researchers at home and abroad have proposed some structures and components with self-centering property successively in recent years.By using various self-centering mechanisms,they can help the structure recover its initial design function without repair or with a little repair after the earthquake.The self-centering brace system is one of them.In this thesis,a novel Pre-Pressed Spring Self-Centering Cable Brace(PS-SCCB)system has been proposed.It consists of a self-centering system adopting pre-pressed disc springs,an energy dissipation system using friction mechanism,and a cable,which is light weight and high strength,can reduce the seismic response of the structure.The hysteretic performance of the PS-SCCB has been studied by theoretical analysis,experimental study and finite element simulation.The main issues are as follows:(1)The configuration of the PS-SCCB was illustrated in detail,the mechanics was explained,and the load-deformation formula was deduced.The relationship between the activation load and lateral deformation of the structure was established.The calculation method of energy dissipation and equivalent viscous damping ratio was presented,and the influence of key parameters on the mechanical behavior of PS-SCCB was discussed.(2)Cyclic loading tests were carried out on the three sub-systems of the PS-SCCB,including the cable,the self-centering system,and the energy dissipation system.The results showed that the high-strength steel strands had the characteristics of high bearing capacity and strong elastic deformation capacity,and they remained elastic all the time during the loading;the self-centering system based on the disc springs kept elastic under the test without residual deformation or stiffness loss,and had stable working performance;the friction system had almost no friction loss after repeated loading and had good durability.There was a linear relationship between bolt torque and friction force.(3)Cyclic loading teste were carried out on the PS-SCCB specimen.The results show that PS-SCCB can achieve complete self-centering when the prepressure of the springs is not less than the friction force.Otherwise,the PS-SCCB cannot achieve self-centering.After repeated loading,the bolts of PS-SCCB become loose,which is not desirable for energy dissipation.The energy dissipation capacity of PS-SCCB can be quickly recovered by tightening the bolts once again.When the spring force is close to the elastic limit,the PS-SCCB will have the stiffness enhancement phenomenon,but slight stiffness enhancement will not affect the self-centering performance of the PS-SCCB.(4)The finite element model of the PS-SCCB was established,and its correctness was verified by the comparison between the simulation results and the theoretical analysis.The effects of different friction forces and the pre-pressure combination of the disc springs on the hysteretic performance of the PS-SCCB were studied.