Seismic Performance Of Precast Piers Connected With Both Grouted Splice Sleeve And Grouted Central Tenon

As a part of Accelerated Bridge Construction(ABC)techniques,the use of precast bridge column has the potential to improve bridge construction in terms of rapidity,quality and environmental impact.The structural behaviour distinction between the precast and cast-in-place piers becomes the main concern in seismic regions.Grouted splice sleeve(GS)is one of typical connectors in precast concrete piers,which offers reliable one-to-one connection of ED bars between precast segments.However,such connection details will render the precast piers experiencing much less shear force and displacement ductility compared with corresponding cast-in-place(CIP)piers,verified by many hysteretic loading tests.In order to improve the seismic performance of precast piers,a new type of intersegment connection with both grouted splice sleeve and grouted central tenon(GS-GT)was proposed.Specimen tests,numerical computation and theoretical analysis were conducted to evaluate this GS-GT connection for accelerated bridge construction.Specific contents are as followed:(1)Summarizing the existing connection types for precast concrete columns.Discussing previous experimental studies and computational studies of precast piers connected with grouted splice sleeve(GS).The construction method and design concept of GS-GT connector was introduced.(2)A quasi-static cyclic test was conducted with three kinds of pier specimens,including a conventional cast-in-place(CIP)benchmark pier,a precast pier with GS,and a precast pier with GS-GT connections.Their damage modes were observed during the cyclic loading tests,and some seismic indices were identified and contrastively analysed.(3)Numerical models were established to simulate hysteretic behavior of GS and GS-GT connector based on OpenSees.The characteristic of metallic sleeve,grouted tenon,unbonded region of ED bars and bond-slip effect are taken into consideration for simulation model.Simulation results were validated by experiment results.(4)A plastic rotation model at the segment interface regions was developed based on the characteristic of GS and GS-GT connector,while moment-curvature relationship was calculated.Furthermore,a simplified analytical method for pushover analysis was proposed for both single-column pier and two-column pier.This method take into account relocation of plastic hinge and redistribution of internal force.The theoretical force-displacement results are verified by experiments.(5)Performance levels were established quantitatively based on test results,and the target displacement of precast piers were evaluated through capacity spectrum method.The performance-based design approaches for the precast concrete piers were developed.The feasibility of the proposd method is validated through an example on the seismic design with pushover analysis.