Numerical Study On Structure Type And Seismic Performance Of Assembling Pre-stressed Bridge Piers

The construction technology of cast-in-place reinforced concrete bridge piers is mostly adopted in the lower structure of bridges in China.The construction method is complicated and the quality of construction can not be guarantee,and surroundings are greatly affected during the process.In order to meet the requirements of building industrialization and environmental protection construction,prefebricated prestressed pier has become a development trend of bridge architecture.The prefebricated prestressed pier is fectory-prefebricated and field installed,which shortens the construction period of the entire project and has little interference to circumjacent traffic.As the main loading component of the bridge,the pier is prone to be damaged under earthquake actions.The uncertainty of prestressed bridge pier's seismic performance limits its popularization and application in seismic areas.Therefore,it is necessary to conduct a comprehensive and systematic study on structural form and seismic behavior of prefebricated prestressed pier.This study take different structural forms as our research object,and establish solid element models to analyze the seismic performance of piers with different structural forms.The main research contents and conclusions are as follows:(1)Summarize characteristics of damping and energy dissipation of different types of prefabricated bridge pier,also analysis moment-curvature and checking shear strength of pier joint's weak position(2)Give a reasonable modeling method for seismic analysis of pier which is to use ABAQUS solid elements.Firstly,established a finite element analysis model of solid elements of ordinary reinforced pier and prefebricated prestressed pier.Studied and solved the constitutive concrete reinforcement and selection of material parameters,prestressing application and contact relationship simulation,which would influence computational convergence and accuracy in the modeling.Conparing analysis results of two pier models,finite elements and the corresponding experimental results,which verified accuracy of modeling method and laid a foundation for further research.(3)Establishe three solid element models,the piers were calculated and analyzed thier bearing capacity and energy dissipation behavior under low cycling loading.Meanwhile study the influence laws of five parameters on seismic behavior.The results showed that prestressed tendons with bonded prestressed piers would have local yiekding and not suitable for using in earthquake areas.Unbonded prestressed piers're-centering capacity is able to be strong,but its bearing capacity and energy consunption are able to be low.Unbonded prestressed piers with built in energy-dissipating bar has advantages such as strong energy consumption,small residual displacement and better seismic performance.(4)Select different types of seismic waves(near faults with pulse waves,near faults with no pulse wave and far-field wave),designs two situations as multiple earthquakes and rare earthquake considered the design of 8 degree earthquake intensity category regions,calculate the model of unbonded pre-stressed pier with built-in energy dissipating steel bars under seismic actions,pier top response and local stress at pier bottom of unbonded prestressed pier model and ordinary reinforced concrete pier modeL The results showed that the pulsed ground motion of near fault would lead to the deformation of the above three fabricated bridge piers.Under rare earthquake in 8 degree zone,even the top displaceeent of the unbonded prestressed piers with energy-consuming steel bars could not be effectively limited.(5)For the purpose of controlling post-seismic residual displacement of prefabricated prestressed piers,this paper studies the unbonded prestressed piers with external angle steel connections.Calculate contributions of angle connections to initial stiffeess of pier and bearing capacity,as well as seismic behavior of pier which under low cyclic loading and pulse-type ground motions.The results showed this structure form is able to have strong self-centering capacity and better seismic behavior.Simultaneously gave a simplified modeling and analysis method that replaced single steel-bolted connection with ideal rigid joint of angle steeL this method is able to have simpler modelling,higher calculation accuracy and better anastomosis with actual modeL The results of this paper provided important reference to practical project application of unbonded prestressing pier with external angle steel connection.