Global Structure Analysis And Optimal Design Of The Pier In T-type Rigid Bridge Constructed With Rotation Method

Because of their high construction efficiency and little interference to the normal traffic,T-type rigid frame bridges constructed with rotation method have been more and more widely used in the construction of the overpass bridges.The application of high strength and lightweight materials in the upper structure of T-frame bridges can greatly reduce the weight of the structure,improve the mechanical performance,and further improve the span ability.However,designers often use reinforced concrete materials in the current T-frame bridges'pier design,and seldom use other types of materials.Therefore,it has important theoretical significance and engineering value to optimize the design of piers and discuss the application of other types of materials in T-frame bridges constructed with rotation method.A 2×100m T-frame bridge in Wohushan,Taiyuan,Shanxi was taken as the engineering background.According to the design data,the finite element model was established by Midas Civil 2015 to analyze the static and dynamic responses during the construction stage and the bridge operation stage.Furthermore,the applicability of the three kinds of piers including steel pier,steel-concrete composite pier and ultra high performance concrete(UHPC)pier,was discussed in the T-frame bridges constructed with rotation method.The finite element model was used to analyze the static response of the T-frame bridge in construction stage and operation stage.The results showed that the T-frame bridge was safe and reliable,and the rigidity satisfied the design requirements.In the rotation construction stage,the stress level of the main girder was high,while the high stress region was large,while played a controlling role in the design of the section beam near the main pier.The seismic response of the T-frame bridge was analyzed in the methods of response spectrum and time-history analysis.The results showed that the structural stress was safe under the actions of the El and E2 earthquakes.The design of main pier was controlled by the seismic design,while the lateral flexural performance of the pier is more negative than longitudinal.The results of time-history analysis were generally smaller than the response spectrum analysis,which could meet the requirements of no less than 80%of the results of response spectrum analysis under the E1 earthquake.The structural eigenvalue analysis showed that the right side pier's rigidity is not enough,which was not conducive to the deformation control of the structure,so it is necessary to improve the side pier's rigidity.Combined with the model calculation and analysis,the design of main pier of the T-frame bridge was optimized.Firstly,the three types of piers including steel pier,steel-concrete combination pier,UHPC pier,were taken out.Then the results of the static and dynamic analysis of the three types of piers were compared with the original concrete pier in construction stage and operation stage,and the applicability of the optimal design scheme of the pier was also discussed.The results showed that the three types of piers can meet the requirements of structural force.Before the rotation construction stage of the T-frame bridge,the steel-concrete combination pier was constructed as a steel structure,while the concrete was poured in after rotation.So the steel-concrete combination pier not only taken the advantages of light weight of swing erection,simple connection with steel girders,but also had the characteristics of large rigidity,high flexural capacity and good seismic performance.Therefore,the steel-concrete combination pier was a more suitable pier for the construction of T-type rigid bridge constructed with rotation method.