| Prefabricated pier has the advantages of rapid construction,energy saving and environmental protection,and the prefabricated concrete-filled steel tube pier has good flexural,co MParessive and shear performance.The prefabricated concrete-filled steel tube pier combines the advantages of prefabricated pier and concrete-filled steel tube pier,which is the main direction of the future bridge construction and development.At present,the seismic safety of fabricated concrete-filled steel tube pier cannot be accurately evaluated due to the few studies on its seismic performance in high intensity area,which limits its application in high intensity area.Based on a continuous girder bridge project in Yunnan Province,the seismic performance of fabricated concrete-filled steel tube pier in high intensity area is studied by finite element software through natural vibration characteristics analysis and dynamic time-history analysis,which can provide some reference for bridge structural design in high intensity area.The main research contents and conclusions of this thesis are as follows:(1)Considering the special mechanical properties of fabricated concrete-filled steel tube structure,this thesis takes a continuous girder bridge in Yunnan as the background and proposes to replace its reinforced concrete pier with fabricated concrete-filled steel tube pier for research.The finite element software MIDAS CIVIL was used to establish the calculation models of fabricated continuous beam bridge with reinforced concrete piers and continuous beam bridge with reinforced concrete piers.Firstly,the natural vibration characteristics of continuous beam bridge with reinforced concrete piers and fabricated continuous beam bridge with concrete filled steel piers were analyzed by multiple Ritz vector method.The first six order vibration modes of the continuous girder bridge with reinforced concrete piers and the prefabricated continuous girder bridge with concrete-filled steel tubular piers are obtained.It can be seen that the natural vibration frequency of the prefabricated continuous girder bridge with concrete-filled steel tubular piers is greater than that of the continuous girder bridge with reinforced concrete piers,and the overall stiffness is greater.(2)The finite element software MIDAS CIVIL was used to analyze the dynamic time history of the continuous girder bridge with reinforced concrete piers and the prefabricated continuous girder bridge with concrete filled steel tubular piers,and the axial forces and bending moments of the two piers under different seismic waves were obtained.Furthermore,XTRACT software was used to build fiber models of reinforced concrete pier and prefabricated concrete-filled steel tube pier respectively,and the yield bending moments of the two piers under the most unfavorable conditions were obtained.By co MPaaring the bending moment under the most unfavorable condition obtained from the time-history analysis of reinforced concrete pier and fabricated concrete-filled steel tube pier with the yield bending moment obtained by XTRACT software,it can be seen that reinforced concrete pier and fabricated concrete-filled steel tube pier are in the elastic state under different seismic actions.But the seismic performance of fabricated concrete-filled steel tube pier is better than that of reinforced concrete pier in high intensity area.Considering the safety and economy of the structure,it is of great practical significance to optimize the structure and related design parameters of fabricated concrete-filled steel tube pier.(3)In order to solve the nonlinear problem,the finite element software ABAQUS is used to establish the finite element model of fabricated concrete-filled steel tube pier and carry out numerical analysis.In order to verify the reliability of the numerical simulation,the modal of the Abaqus full bridge model is verified first,and co MPaared with the Midas model of the continuous beam bridge,the results show that the dynamic characteristics of the two models are consistent,which further verifies that the Abaqus finite element model is reliable in some parameters and boundary settings.Next,the structure of fabricated concrete-filled steel tube pier is optimized by adding cap,rivet and ring plate,and then the influence of design parameters such as pier hollow ratio,diameter to thick Ness ratio,slenderness ratio and strength of concrete-filled steel tube material on seismic performance of fabricated concrete-filled steel tube pier is studied,and the safety and economy of bridge construction are integrated.The optimization suggestions on structure and related parameters of the fabricated concrete-filled steel tube pier in the design process of this bridge are put forward to provide some reference value for the design of the fabricated concrete-filled steel tube pier in the high intensity area in the future. |
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