Comparison And Analysis Of Seismic Performance Of New Self-Centering Piers And Traditional Self-centering Piers

The primary problem of ductility design widely used in pier seismic design nowadays is the excessive residual deformation after earthquake,which makes it difficult to repair,not conducive to disaster relief work,and also causes huge economic losses.The self-centering pier sways under earthquake,consumes seismic energy by energy dissipation components,restores to its original position by self-centering components and gravity action,and doesn't produces any residual deformation under earthquake,which ensures the basic transportation capacity of the pier and is easy to repair.The traditional self-centering pier its cap joints with abutment are prone to compression failure,and the even abutting joint can't resist shear force,which can easily lead to the shear failure of prestressing steel bars.In view of these shortcomings,a new type of self-centering pier is proposed in this paper.Two kinds of pier finite element models are established by ABAQUS.Gets the quasi-static results and dynamic time-historical of the two models,and compare their seismic performance.(1)The structural composition of the traditional self-centering pier is analyzed,and the shortage of the traditional self-centering pier is pointed out.The structural composition of the new self-centering pier is proposed for these shortcomings.The energy consumption and hysteresis performance of different energy dissipated devices,are analyzed.The advantages and disadvantages of different joint forms of self-centering piers are analyzed,according to the structural characteristics of the new self-centering pier,the built-in energy-dissipating steel bar and ball-in joint are selected.(2)Based on the flexural strength,shear strength and lateral stiffness of the new selfcentering pier,a displacement-based design method of self-centering pier under the four-level seismic fortification standard is proposed.The design steps of the proposed method are demonstrated by an example analysis.It is proved theoretically that the bending bearing capacity of the new self-centering pier is higher than that of the traditional self-centering pier,and the lateral stiffness of the new self-centering pier is equivalent to that of the traditional self-centering pier.(3)The finite element model of traditional self-centering piers and new self-centering piers was established by ABAQUS software and their quasi-static analysis was carried out.According to the results of quasi-static analysis,the quasi-static analysis results show that the yield load,ultimate load and energy dissipation capacity of the new self-centering pier are higher than those of the traditional self-centering pier.(4)The paper studies the influence of the prestressed steel bar and the energy dissipation steel reinforcement ratio on the seismic performance of the new self-centering piers.Increasing the pre-tension of prestressed steel bars and increasing the reinforcement ratio of energyconsuming steel bars can improve the stiffness,yield load,ultimate load and energy dissipation capacity of the new self-centering piers,but the structural ductility will be reduced.(5)The dynamic time-historical analysis of the new self-centering pier and the traditional self-centering pier shows that the displacement of the pier top caused by the new self-centering pier under earthquake action is smaller than that of the traditional self-centering pier,moreover,the energy dissipation capacity of the new self-centering pier is better than that of the traditional self-centering pier.The lower spiral stirrup column enhances the local compressive bearing capacity of pier columns and makes the stress value in concrete smaller.