Study On Seismic Performance Of Isolated Structure With Response Amplification Shape Memory Alloy Damper

Isolation technology is the most mature and widely used technology in structural control technology.Base isolation refers to the installation of isolation devices(such as rubber bearings,friction pendulums,etc.)between the bottom of the structure and the upper part of the foundation to increase the natural vibration period of the structure and prevent the transmission of seismic energy to the structure above the isolation layer,so as to achieve the effect of vibration reduction.However,in case of extremely rare earthquake,the isolation device may produce excessive displacement,which will cause it to exceed its limit displacement and be damaged,unable to play the isolation role,and bring great security risks to the building structure.The limit device is usually set in the isolation layer to avoid this situation.However,the existing limit device has some defects,such as small deformation capacity,poor energy consumption capacity,and difficult to provide large tonnage damping force,which can not really limit the displacement of the isolation layer.In this paper,a response amplified shape memory alloy damper(CRAD-SMAD,Shape Memory Alloy Damper with Cam Response Amplification Device),which can amplify the response of displacement,velocity and force,can transform the large horizontal linear motion under the action of earthquake into the small reciprocating linear motion in the vertical direction,and the additional SMA damper has been moving within the limited range of travel,which can ensure that it will not fail in the earthquake action,and can be used as energy dissipation device and limit device in engineering.In this paper,the restoring force formula of CRAD-SMAD is derived,the experimental analysis of the device is carried out,and the simulation program is compiled to analyze the seismic performance of the structure system with CRAD-SMAD.The main research contents are as follows:1?The design of response amplification SMA damper and the derivation of its restoring force formula: through browsing a large number of domestic and foreign related literature,the research progress of SMA damper,amplification device and limit device is understood,and the existing problems are analyzed.Then a CRAD-SMAD limit device of response amplification SMA damper is developed,and the detailed introduction of the device is given According to the structure and working principle of the device,the theoretical calculation formulas of CRAD-SMAD restoring force and response magnification are derived.2?The pseudo-static test of CRAD-SMAD limiter: firstly,the mechanical properties of SMA were tested,the transformation temperature of SMA was analyzed,and the change of mechanical properties with the number of loading cycles,amplitude and speed was studied.Design and process CRAD-SMAD limit device.Based on the pseudo-static test of CRAD-SMAD,the hysteretic curves of CRAD-SMAD and SMA damper under different loading amplitude,loading frequency and loading speed are analyzed.The simulation program of CRAD-SMAD device test is compiled with MATLAB software,and compared with the test results,in order to verify the correctness of the recovery force formula of CRAD-SMAD device and reveal the change rule of mechanical properties of the device.3?Seismic response analysis of CRAD-SMAD single degree of freedom energy dissipation system: Using MATLAB software to compile time history analysis program,the seismic response of single degree of freedom energy dissipation system without control system,single degree of freedom energy dissipation system with CRAD-SMAD device and single degree of freedom structure energy dissipation system with traditional SMA damper are compared under 7 seismic waves.The damping effect of three systems under the action of frequent earthquake,rare earthquake and extremely rare earthquake is studied.Finally,the dynamic amplification coefficient of the single degree of freedom system with CRAD-SMAD is analyzed under the harmonic load,and the variation rule of the dynamic amplification coefficient with the parameters is obtained.4?Seismic response analysis of CRAD-SMAD two degree of Freedom Isolation limit system: the superstructure of the isolation structure is simplified as a single mass point,and the isolation layer forms a two degree of freedom isolation system.In this paper,CRAD-SMAD is installed in the isolation layer as the isolation layer limit device to study the limit effect of two degree of Freedom Isolation System under rare earthquake and extremely rare earthquake.5?Seismic response analysis of shear type isolation structure with CRAD-SMAD limit device installed in the isolation layer: the time history analysis program of multi degree of freedom isolation structure with CRAD-SMAD limit device installed is compiled by MATLAB software.The seismic performance of the isolation system with CRAD-SMAD limit device and the isolation system with SMA damper limit device are compared and analyzed under rare and rare earthquake.6?The energy-based design method of CRAD-SMAD isolation limit system: the design criteria and standard energy design response spectrum of the base isolation structure are introduced,the energy design equation of the base isolation structure is established,and the deformation prediction formula of the rubber bearing plus shape memory alloy damper isolation device is deduced.Based on the principle of equal energy,the method to determine the design parameters of CRAD-SMAD is given.The energy design method of this kind of structure system is studied,and the design method,steps and design examples are given.