Self-centering Seismic Performance Of Thin-walled Hollow Pier With Shape Memory Alloy

Nowadays,the economic development of the society is faster and faster,the number of bridges is more and more,and the earthquake disasters occur frequently,which causes the collapse of the bridge structure,resulting in serious damage to the main load-bearing members and excessive residual deformation and other consequences.The importance of the bridge is self-evident,in today’s environment,people’s demand for the bridge is not only limited to the initial traffic,the safety and seismic requirements of the bridge should also be improved.The structural requirements of " No damage occurs in small earthquakes,can be repaired in medium earthquakes,and does not fall in large earthquakes" are not enough to meet the needs of today’s society,so it is necessary to supplement and improve the more effective structural seismic design code.As a central hub to secure links between the quake zone and the outside world,the safety of the bridge structure under the earthquake and the good performance after the earthquake are of great significance to the social economy,but compared with the superstructure and the foundation cap,the seismic performance and design of the pier system are very important,so it is urgent to improve the seismic performance of the seismic pier system.The research method of this paper is based on the theory of performance and energy dissipation,and the numerical simulation of self restoring piers with SMA is carried out by using the finite element software ABAQUS.By changing the relative parameters,such as aspect ratio,axial compression ratio,SMA spacing,SMA reinforcement ratio and longitudinal reinforcement ratio to determine the energy dissipation performance of the self-reposition pier with the optimal parameters of SMA,and verify its superiority.The main contents of this thesis are as follows:(1)This paper introduces the form of seismic damage of bridge,compares and analyzes the difference of seismic design principle of self-reset pier,assembly pier and integral cast-in-place pier,and analyses the difference of seismic performance of three kinds of piers in terms of residual displacement,overall stability,ductility,side resistance and energy dissipation.(2)In this paper,the components and related design of self restoring piers are introduced in detail,the related mechanical mechanism of self restoring piers is studied,the research and development process of SMA in self restoring piers is summarized,the mechanical performance characteristics and constitutive model of SMA are introduced,and the correctness of the simplified constitutive model is verified.(3)Based on the finite element analysis software ABAQUS,the self restoring pier model and the traditional cast-in-place pier model are established.At the same time,a new type of pier with SMA instead of prestressed reinforcement and energy dissipating reinforcement in self restoring pier is proposed for numerical analysis.The parameters of longitudinal reinforcement and stirrup of the three piers are the same.The displacement force hysteretic curve and other parameters of the three piers are compared and analyzed differences in relevant seismic performance parameters.(4)The effects of slenderness ratio and axial compression ratio on the seismic performance parameters of self restoring hollow piers with SMA,such as displacement force hysteretic curve,top lateral displacement,top lateral force,yield load,ultimate load,yield displacement,ultimate displacement,equivalent stiffness and residual displacement,are studied to determine the optimal slenderness ratio and axial compression ratio.(5)On the basis of the optimal slenderness ratio and axial compression ratio of the pier model,the influence of SMA spacing,SMA reinforcement ratio and longitudinal reinforcement ratio on the seismic performance of the pier is studied,so as to determine the optimal parameters of the self restoring pier model with SMA.