Theory Research On Seismic Performance Of Unbonded Prestressing Precast Segmental Pier

The structural components, mechanical properties, analytical methods and thedesign method based on the material strain of Segmentally Assembled Self CenteringPier (SA-SCP) is studied. By combining theoretical analysis and numericalsimulation, the flexural capacity, shear capacity, hysteretic performance and designmehtods of the proposed SA-SCP are investigated. The main work and results of theresearch are as follows.(1) The excellent performances of the segmentally Assembled Pier are exploredby reviewing part of the existing experimental results, theories and FEM simulations.By reviewing the literature, the relative experiments, analytical model and numericalsimulations for SA-SCP are compared.(2) The SA-SCP is decomposed into5fundamental components including loadbearing components, self centering components, joint component, energy dissipatingcomponents and shear key. The structural function and mechanical properties of eachcomponent are discussed and the flexural capacity and shear capacity are analyzed.(3) A two parametered exponential (TPE) confined concrete constitutive relationwith controllable softening features is proposed. Considering the material andgeometry nonlinearity, the TPE confined concrete constitutive relation is utilized tosimulate6groups of circular concrete filled steel tubes and6groups of retangularconcrete filled steel tubes based on Abaqus. The numerical simulation results matchthe experimental results and the reliabilty of the constitutive model is validated.(4) Based on OpenSEES, the SA-SCP-Fiber finite element model is constructedby taking concrete filled steel tube SA-SCP as example. The results of SA-SCP-Fibermodel, such as hyperestic performance etc., are compared with the experiments. Athorough parametric study on the influence on SA-SCP seismic performance withrespect to segmental slenderness ratio, initial prestress, cross section area ofprestressed reinforced bars, ratio of radius to thickness and axial compression ratio isconducted.(5) A simplified analytical model of SA-SCP is proposed based on plastic hingetheory. Based on the hypothesis of SA-SCP plastic region, a simplified bilinearequivalent model of SA-SCP is establised according to the capacity equavalence principle. By assuming the relation between material strain and pier top displacement,a performance based design method for concrete filled steel tube SA-SCP is proposedintuitively.This research was supported by the Tsinghua University, independent researchfunded project (20101081766) funded, hereby expressed gratitude.