Damping Mechanism And Design Method Of Hyperboloid Damping Device With Negative Stiffness Of Bridge SMA

There are a large number of bridges in the high intensity earthquake area of China,and these bridges generally have seismic isolation bearings.However,under the action of earthquake,there are often falling beams and large residual deformation.In order to improve the limit ability and reduce the residual deformation,a new material shape memory alloy(SMA)was introduced into the shock absorber.However,SMA damping device will increase the internal force response of the bridge substructure.How to reduce the internal force response of the structure has become a new problem to be solved for SMA damping device.The negative stiffness system can effectively solve the above problems.Negative stiffness refers to the same direction of the restoring force and displacement.The normal stiffness of the traditional isolation device is the opposite direction of the restoring force and displacement.In order to study the damping mechanism of SMA negative stiffness hyperboloid damping device,the following research work is carried out in this paper:(1)This paper puts forward a kind of SMA negative stiffness hyperboloid damping device,and puts forward the design requirements,design points and specific design scheme of SMA negative stiffness hyperboloid damping device.According to the action mechanism,the restoring force model of SMA negative stiffness hyperboloid damping device is proposed,which provides a certain basis for the study of constitutive model of SMA negative stiffness hyperboloid damping device.(2)Based on ANSYS software,the SMA negative stiffness hyperboloid damping device is established.Through theoretical derivation and numerical simulation,the SMA constitutive model is analyzed,and the stress deformation and sliding mechanism of the negative stiffness hyperboloid damping device are analyzed.The displacement,stress and strain of the negative stiffness hyperboloid damping device are studied.In ANSYS finite element software,the SMA negative stiffness hyperboloid damping device,SMA plane damping device and SMA positive stiffness hyperboloid damping device are established respectively for comparative analysis.The analysis results show that the constitutive model of numerical simulation is consistent with the previous assumptions.Compared with the SMA positive stiffness hyperboloid damping device,the SMA negative stiffness hyperboloid damping device can effectively reduce the internal force of the structure.(3)Based on SAP2000 finite element software,a finite element model of a four span continuous bridge is established.The finite element models of bridges with different supports(SMA positive stiffness hyperboloid damping device,SMA plane damping device and SMA negative stiffness hyperboloid damping device)are used.Through the analysis and comparison of the structural responses of three kinds of damping devices,such as horizontal displacement,main beam acceleration,pier bottom bending moment and support shear force,the damping effect of SMA negative stiffness hyperboloid damping device in continuous beam bridge is verified.Furthermore,the numerical results of SMA negative stiffness hyperboloid damping device in ANSYS and SAP2000 are compared and analyzed.The influence of design parameters of SMA negative stiffness hyperboloid damping device on seismic response of bridge is studied.The results show that the moment at the bottom of the pier of the negative stiffness hyperboloid damper decreases in part of the site.Compared with the three kinds of damping devices,the negative stiffness hyperboloid damping device reduces the bridge stiffness,which can effectively reduce the main beam acceleration,pier bottom bending moment and bearing shear amplitude.The purpose of the design of SMA negative stiffness hyperboloid damping device is realized.