Study On Seismic Mechanism Of Passive Energy Dissipation Structure With Shape Memory Alloy Damper

Structural vibration control is an effective way to improve structural performance against earthquake and weaken the response of structure under dynamic load. Passive control of structure vibration control are widely applied to practical engineering due to its advantages of simple structure, low cost and easy maintenance. Shape Memory alloys(SMA) are a kind of smart material that possess superelastic effect and high damping characteristics, which make them the ideal material for dampers. Experiment is carried out to investigate a self-centring SMA damper’s mechanical behaviors. The control effect of the self-centring SMA damper in reducing the structural seismic response is studied. The mainly research in this paper is as follows:(1) Experiment is carried out on a self-centring SMA damper. The self-centring SMA damper is mainly composed of pre-tensioned superelastic SMA wires and two precompressed springs, which function as energy dissipation and re-centring group, respectively. Based on the mechanical model of the self-centring SMA damper, two damper specimens are manufactured. The influences of displacement amplitude and loading frequency on the damper’s mechanical behaviors are studied. Design advice of the self-centring SMA damper is given based on the study and analysis.(2) The stress of SMA is affected by strain, temperature and martensite content in the Brinson constitutive model. And the Brinson constitutive model is adopted in the simulation process in order to get the damper’s performance curve. In passive structure, control force of the self-centring damper is driven by the displacement of the structure. Hence, using the strain of SMA to figure out the stress in the process of loading and unloading process based on the Brinson constitutive model is the first step to simulation in the Matlab environment. Solve program for the force and displacement relationship of the damper is compiled according to the mechanical model of the damper. Under the condition of a given specimen parameters, force and displacement curve is obtained by inputting the displacement excitation into the simulation program of the damper. And comparing the numerical simulation curve with experimental curve.(3) A time history analysis program for a five-story steel frame structure with the SMA damper based on Matlab software is compiled. Interlaminar shear model is adopted as the calculation model of the steel frame structure, and the mass of the floor are placed on the floor slab. Using Wilson-θ to solve the time history analysis program. The EL Centro wave, Taft(S69E) wave and an artificial seismic wave are taken as the earthquake excitation.The controlled steel frame structure is analyzed to assess the control effect of the SMA damper in reducing the structural seismic response including displacement, acceleration, interstorey displacement angle and shear force.(4) Using mathematical model to simulate the damper. Using SAP2000 to analyse a three-story controlled concrete structure. The result shows that the SMA damper is effective to control the structural displacement. Comparing the results of numerical simulation based on Brinson model with mathematical model, and the causes of error are analyzed.