Research On The Performance And Application Of SMA Cable Support Based On Viscoelastic Dampin

As a new and effective structural damping device,self-resetting energy dissipation components have the advantages of good energy dissipation performance and superior selfresetting ability.In this thesis,a theoretical analysis,experimental study,and numerical simulation were combined to systematically investigate a composite self-resetting brace based on viscoelastic damping and shape memory alloy cables(SMA+VE)from the perspectives of material,component,and structure.The main research work is as follows:(1)At the material level,cyclic loading tests were conducted on the two main materials of the brace,SMA cables and viscoelastic dampers,to study their cyclic stability.The results show that the strain amplitude used in the training process has a greater effect on the mechanical properties of the trained SMA cables,and training has a smaller impact on the cyclic stability of SMA cables in the hardening stage with large strain amplitudes.Applying pre-strain can reduce the hysteresis characteristics of trained SMA cables.The mechanical performance test of VE shows that it has a deformation capacity of 500% strain amplitude,an equivalent viscous damping ratio of 30%,and low frequency dependency.In addition,the mechanical properties of VE become more stable after undergoing different strain amplitude processes,and the effect of different preloading cycles on VE is small.(2)At the component level,five SMA+VE brace specimens were designed and fabricated,and their mechanical performance was studied through experimental tests.The tests show that the working mechanism of the brace is clear,with SMA cables providing selfresetting ability and VE providing energy dissipation ability,and it has good recoverability,low frequency dependency,and strong robustness.The mechanical properties of the brace become more stable after training.With an increase in cyclic loading cycles,the maximum force of the brace remains relatively stable,but the hysteresis energy dissipation decreases.Reducing the number of SMA cables will lower the bearing capacity of the brace,but it still has a strong self-resetting ability.A small pre-tension will lower the initial stiffness of the brace,and an appropriate increase in pre-tension can reduce the residual deformation of the brace.(3)At the structural level,dynamic time-history analyses were conducted on an eightstory steel frame structure with SMA+VE,SMA,and VE braces to study their seismic performance.First,the mechanical models of SMA,VE,and SMA+VE were established based on Open Sees.Then,dynamic time-history analyses were performed on the models of the steel frame structure with only SMA,only VE,and SMA+VE braces.The results show that in terms of inter-story drift ratio(IDR)and story absolute acceleration(AA),the SMA+VE brace is between the SMA and VE braces,and the composite self-resetting brace has certain damping and self-resetting properties.In terms of residual inter-story drift ratio(RIDR),it is much smaller than the VE brace,indicating good self-resetting performance.A statistical analysis of44 time-history analyses shows that due to the synergistic effect of VE damping and SMA selfresetting ability,the SMA+VE brace has a smaller response dispersion than the other two braces.