| The prefabricated structure has a series of advantages,such as good component quality,high construction efficiency,green environmental protection and less interference to the environment,so it has been widely concerned and promoted by the state and industry in recent years.Based on the engineering background of the urban rail transit bridge in high seismic intensity zone,a new structure scheme of double-column precast segmental concrete-filled steel tube pier was proposed.Its refined model was established based on ABAQUS finite element analysis software.The feasibility and rationality of the structure scheme were verified through three aspects: microscopic damage,joint opening and hysteretic curve.The influence of main factors on seismic performance of precast segmental bridge pier was revealed,and the damage mechanism of such pier was clarified.The main work of this paper is as follows:(1)Based on the quasi-static test results of a precast concrete-filled steel tube pier,a fine pier model was established on ABAQUS finite element calculation platform.By comparing the numerical simulation results with the experimental data,the reliability of the numerical method was verified,which laid an important foundation for the subsequent calculation and analysis.(2)The joint structure between segments with bolts and sliding bolt grooves was proposed based on the investigation of various connection modes of fabricated piers and the summary of the advantages and disadvantages of various shear keys.Combined with the engineering background of urban rail transit pier,a new assembly scheme of double-column precast segmental concrete-filled steel tube pier was proposed.(3)The double-column precast segmental concrete-filled steel tube pier was taken as the research object,connected by sliding bolt.In this paper,the quasi-static analysis method was used to analyze and compare the mechanical properties of the bridge pier.The influence of parameters on seismic performance of pier was discussed,including prestressed tendon ratio,thickness of connecting steel tube,length of connecting steel tube and length of sliding bolt groove.The results show that increasing the prestressed tendon ratio can significantly improve the shear capacity and energy dissipation capacity of piers,but at the same time it can increase the residual displacement of pier.When the prestressed tendon ratio is 0.581%,it can give full play to the performance of prestressed tendon and concrete-filled steel tube.Meanwhile,increasing the thickness and length of the connecting steel tube can strengthen the energy dissipation and shear resistance of the pier and reduce the residual displacement of the pier top.The length of sliding bolt groove should not be shorter than 128 mm,or it can lead to excessive residual displacement of pier top.However,when the length of sliding bolt groove is increased to 148 mm,the further increase of its length may have no effect on the seismic performance of pier.(4)In this paper,based on the parameters analysis of seismic performance,the refined models of piers with or without external connection devices were established respectively,by selecting the prestressed tendon ratio of 0.581%,the length of connecting steel tube of 500 mm,the thickness of connecting steel tube of 6 mm and the length of sliding bolt groove of 148 mm.The quasi-static analysis and dynamic time history analysis under different earthquake levels were carried out to compare the difference of seismic performance of precast segmental concrete-filled steel tube piers with or without external connection devices.The results show that the connection device can reduce the residual displacement of the pier top and improve the shear resistance of the pier.Under the level of frequent earthquake,the pier is in elastic state.Under the level of design and rare earthquake,the segmental steel tubes are partially yielding and the pier is basically in good condition.This kind of bridge pier can be well applied to the high intensity seismic zone. |
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