Study On Seismic Performance And Design Method For Segmental Concrete-Filled Steel Tubular Piers

In recent years,segment assembly technology for bridges is developing very well.For specified environment and design conditions,this technology could reduce the time of construction,and accelerate the progress of the project,significantly.At the same time,the project quality is guaranteed.In this paper,the seismic performance of segmental concrete-filled steel tubular pier and the displacement-based seismic design of the piers are studied.(1)The simulation model of segmental concrete-filled steel tubular pier is established.Considering dry joints and the self-centering characteristics of posttensioned pre-stressed tendon,the proposed model is validated by comparison with a quasi-static test of a segmental concrete-filled steel tubular bridge pier.(2)Using monotonic pushover analysis and cyclic quasi-static analysis,the parameters,such as concrete strength,pre-stressing force,steel ratio of a section,slenderness ratio and axial compression ratio,were analyzed.Analysis of the seismic behavior of concrete-filled steel tubular piers taking into account the effects of different parameters and interaction effects among parameters were carried out.A guidance for design and performance optimization design of this kind of pier was provided.(3)According to the displacement-based seismic design,two algorithms based on displacement for the concrete-filled steel tubular pier are proposed.For the first algorithm,the calculation of the target displacement of pier used the deformation of the joint zone and the rotation of the two plastic hinge zones in the pier.The seismic capacity requirement of the pier is obtained according to the seismic displacement demand,and the ratio of reinforcement and the ratio of pre-stressed tendon of the section can be obtained.The second algorithm follows the seismic design code and design requirements,and takes a certain displacement drift angle as the target displacement.Then section design and the reinforcement ratio can be calculated.(4)Artificial synthesis ground motions of specified site conditions were chosen as the excitation for the nonlinear time-history analysis.The rare intensity seismic responses of the piers using the proposed two algorithm and the seismic design code were compared.It is verified that the reliability and accuracy of the proposed method is good.