Research On Aseismic Control Of Frame Structure With SMA Helical Spring Energy Dissipation Brace

Energy dissipation technology is one of the effective ways of structural control.It can dissipate the seismic energy of the structure in the strong earthquake by setting specific non-load-bearing energy dissipation devices in the structure,and rapidly reduce the structural earthquake response,so as to protect the main structure in the strong earthquake.Shape memory alloy(SMA)is a kind of material with shape memory function.Its unique shape memory effect and superelasticity make it well be used in energy dissipation and vibration control.The application of shape memory alloy to the damping control of engineering structures can not only make full use of the unique properties of SMA materials to expand its application in damping control,but also provide new materials for shock absorption control.So on this basis,SMA helical spring energy dissipation brace is proposed in this paper,which consists of SMA helical spring and ordinary steel wire.It is simple and easy to manufacture and install the new energy dissipation brace.It not only provides energy dissipation,but also has the ability of self recovery due to the superior properties of SMA materials.Firstly,the SMA helical spring used for energy dissipation brace is trained by hot working method.Since the mechanical properties of SMA helical spring are significantly different from those of SMA wire when it is subjected to external force,the constitutive model of SMA wire can not be simply applied.Therefore,the tensile tests of SMA helical spring are carried out for its mechanical properties.Based on the research and analysis,a model of the force-displacement relationship of SMA helical spring is established.By fitting and calculating the hysteresis curve of the test,the mathematical expressions of the model are given and compared with the force-displacement hysteresis curves obtained from the tensile tests.The results show that the proposed model of SMA helical spring can well describe the hysteretic behavior of SMA helical spring.In order to study the energy dissipation effect of SMA helical spring brace,a numerical model of the two-story frame with the new energy dissipation brace is established to simulate the response of the frame subjected to an earthquake.To verify the effectiveness of the numerical model,a corresponding experimental model is made and a series of shaking table experiments are carried out.It is found that the experimental results have very good agreement with the numerical simulation results.Compared with the uncontrolled case,the SMA helical spring energy dissipation brace proposed in this paper can dissipate the input seismic energy well under different seismic waves,and it can also simultaneously reduce the displacement and acceleration response of the structure,which shows superior vibration control effect.Compared with the steel spring brace,the SMA helical spring energy dissipation brace can exert the shock absorption function under different earthquake and provide better vibration reduction effects.Considering its capabilities of energy dissipation as well as fully re-centering,the SMA helical spring energy dissipation brace has a great potential for frame structural vibration reduction.