Research Of Shape Memory Alloy-suspension Pendulum Damping System In Applying To Protect Pagoda

The pagoda is a shinning pearl in the ancient architectural history of China,it is not only a beautiful architectural form,and has an historical and cultural value.But natural disasters and man-made damage are more serious because these ancient pagoda was built long time,so they are very need to be protected.At present,Chinese pagoda research work mainly focused on salvage recovery,and for research on how to reduce the earthquake response of the tower structure is comparatively rare.Therefore,we study a suited to reduce the earthquake response of the tower structure of Shape Memory Alloy-Suspension Pendulum Damping System(abbreviated SMA-SPDS)according to the seismic protection principle and the basic requirements of the tower structure in this paper,and do the finite element analysis after the integration,the main work is as follows:(1)Mechanical properties tests were carried out SMA of 1.2mm silk material or 0.5mm,and 0.8mm with 1.0mm respectively.We studied that the diameter of the wire and the loading cycles exerts effect on material stress-strain curve and the main mechanical properties,and established the piecewise linear constitutive model.Results shows that wire cumulative residual strain increases slightly with the increase of cycling times and stress-strain curve of each feature point stress value tends to be stable with the increase of cycling times,but residual deformation a single cycle was reduced.Material stress-strain curve feature point stress value is slightly lower and its value about 5%,or little change of energy dissipation capacity when the wire diameter increase from 0.5 mm to 1.2 mm.This illustrates that material mechanics performance is stable and can be used for SMA-SPDS research.(2)We developed a SMA-SPDS witch basic does not affect the original ancient pagoda and historical information,facilitate integration and suitable to reduce the earthquake response of the tower structure used with special mechanical properties of the SMA materials,in the light of the existing masonry pagodas structure,especially the main characteristic of the small wild goose pagoda structure.The dynamic performance of the SMA-SPDS under 12 kinds of working conditions were measured by changing of the three kinds of physical and mechanical parameters in SMA–SPDS,and it was concluded that the corresponding natural frequency and damping ratio.Results show that the SMA-SPDS damping ratio whose adjustable range is larger or adjustable and controllable frequency range was between 0.0045 and 0.1529 that can meet the needs of the shock absorption tower structure.(3)The shaking table test of SMA-SPDS was carried out under a variety of working conditions and SMA-SPDS damping performance was studied through the input sine wave and the actual recording seismic waves.Based on the analysis of the test results,output of SMA-SPDS in sine wave excitation and under the action of seismic wave is larger,as well stable and reliable working performance.The equivalent damping force of SMA-SPDS increases with increasing of the peak of shock wave under 12 kinds of working conditions and growth is accelerated.This shows the earthquake excitation is more intense and SMA-SPDS damping effect more obvious.Phase difference of relative displacement of quality mesa of SMA-SPDS and velocity of phase are close to 180 °.This suggests the direction of SMA-SPDS output and structure seismic action is opposite.Which can reduce the earthquake effect of the structure.(4)The study of SMA-SPDS parameters optimization was carried out by the theoretical analysis and numerical simulation.Results show,shock absorption effect of SMA-SPDS also will increase with the increase of ratio of quality of SMA-SPDS mass and quality controlled structure.However,they are gradually stabilized.There exist the optimal frequency ratio and damping ratio,which can be optimized selection in application at the same time.In addition,damping scheme design was made under the single mode control and the multi-modes control according to the actual situation of the small wild goose pagoda structure.The SMA-SPDS design parameters is given under all kinds of shock absorption solution.And integrate the optimization of the SMASPDS to the small wild goose pagoda.The finite element analysis was carried out on the various vibration damping schemes by using the software(Abaqus)of the finite element analysis.Calculation results show that the proposed various damping scheme on earthquake response of the small wild goose pagoda has reduced,multimodal control can effectively improve the stability of the SMA-SPDS,and can improve the damping effect of the small wild goose pagoda.