Analysis Of Seismic Resilient Deformation Performances Of SMA-concrete Structures

As one of frequent earthquake happening countries in the world,China has always paid close attention to research of the seismic performance and resilient deformation performance of common reinforced concrete(RC)structures and members.Shape memory alloy(SMA),a kind of smart material,has characteristics of shape memory effect(SME),super elasticity(SE),high corrosion resistance,high damping ratio,high electrical resistance and other characteristics that conventional materials do not have.It has a wide range of application prospects in the energy dissipation and shock absorption of structures.Open SEES(Seismic Engineering Simulation Open System)as a finite element software launched in 1999,has advantages of good architecture and openness with a wide range of use.In the dissertation,based on the outstanding hysteretic energy dissipation performance and resilient deformation of the super-elastic SMA material,a new type of SMA damper with high rigidity,good energy dissipation and good resilience is developed to improve the seismic resistance and resilient deformation capacity of RC frame structures with the new dampers,aiming at proposing an analysis method for the internal forces and deformations of the SMA-structures and members under earthquake actions.To this end,based on the Open SEES platform,a nonlinear finite element analysis for the structural members of SMA concrete shear walls,SMA frame beam-column joints and SMA diagonal bracing RC frames under earthquake actions was carried out,and the main contents include as following:(1)At the material level,the research on hysteretic properties of superelastic SMA material is carry out,focusing on the energy dissipation capacity and resilient deformation capacity of the material.The results show that when the parameters are selected reasonably,the selected Hysteretic Material model can well simulate the hysteretic performance of the superelastic SMA bars.The selfcentering model was selected as the restoring force model of SMA damper based on Open SEES,which laid the foundation for the seismic analysis of structural members.(2)At the component level,based on the Open SEES finite element analysis platform,SMA concrete beam-column joints and SMA concrete shear walls are numerically simulated under pseudo-static loadings.On the one hand,it is compared with relevant tests to verify the accuracy and effectiveness of the established model;on the other hand,the parametric analysis of the verified model is carried out to obtain its basic laws that affect the seismic performance and resilient deformation performance of structural members.The results show that the seismic performance and resilient deformation performance of shear walls changewith parameters of the edge SMA bar ratio,edge stirrup reinforcement ratio,axial compression ratio,height to width ratio and other parameters.The seismic performance and resilient deformation performance of SMA beam-column joints are closely related to the parameters of the stirrup ratio of the joint area,diameters of SMA bars,and axial compression ratio.(3)At the structural level,based on the Open SEES finite element platform,a dynamic analysis for both four-bar-link SMA damper bracing system and the three(3,6 and 9-storey)RC frame structures installed with the new bracing system under both pushover and rare earthquake loadings are performed,respectively.The results show that the new four-bar-link SMA damper bracing system has a very significant contribution to the seismic performance and resilient deformation performance of structures.The peak corresponding responses(displacement,velocity,acceleration and drift)of controlled structures are obviously reduced with the increase of story number.