Study On Seismic Performance And Design Method Of Continuous Rigid Frame Bridge With Ultra-high Piers Of Concrete-filled Steel Tubular Laminated Laced Column

Ultra-high pier continuous rigid-structure bridge with concrete-filled steel tube(CFST)laminated laced column as a rigid skeleton and reinforced concrete(RC)as a composite high pier has the advantages of good overall seismic performance,high bearing capacity and structural stiffness,high ductility,beautiful shape and material saving,It has become one of the ideal bridge types of high pier bridge across valley in seismic area.At present,the basic research on seismic performance of this kind of new type of high pier bridge structure is less,and the engineering design lacks theoretical basis.Therefore,this paper takes Labajin Bridge in Sichuan as the engineering background,analyzes the elastic-plastic seismic performance,failure mode and the seismic applicability of the main design parameters of the super-high pier continuous rigid frame bridge with super-qualified concrete filled steel tube,and establishes the structural ductility mechanism and seismic design optimization criteria.(1)A three-span model for calculating Ultra-high pier continuous rigid-structure bridge with concrete-filled steel tube(CFST)laminated laced column is established to study the dynamic characteristics and internal force distribution of structures under earthquake action.The design parameters of E1 earthquake action(stiffness ratio,axial compression ratio,high height ratio),column limb parameters(pier height,slope,concrete strength etc.),column limb connection parameters(slab thickness,concrete strength etc.)are analyzed.The results show that the stiffness ratio,axial compression ratio,pier height/aspect ratio,high and low pier height ratio and column limb inclination are the important parameters affecting the elastic seismic performance of CFST stacked qualified structural piers.According to the range of the proposed design parameters,the seismic optimization design of continuous rigid frame bridge with super-high-piers with super-qualified concrete-filled steel carried out.The optimized calculation model can effectively reduce the seismic response value and improve the internal force distribution of the structure.(2)A systematic study the elastic-plastic seismic performance,ductile energy dissipation mechanism of continuous rigid-structure bridges with super-high-laminated laced column under E2 seismic action of concrete-filled steel tubular(CFST),reveals the influence of the main design parameters on the ductility of laminated structural piers,and establishes seismic optimization design criteria.According to the results,the concrete-filled steel tube stacked qualified structure pier has good ductility and seismic dissipation performance.The curvature ductility coefficient of the control section is ??7.49,and its nonlinear deformation ability is stronger than that of the conventional reinforced concrete pier,which is similar to that of the concrete-filled steel tube lattice column pier.With the increase of stiffness ratio of beam pier,height ratio of high and low pier,slope degree of column limb,the ratio of plate thickness to outer diameter of column limb,and the decrease of axial compression ratio,the ductility performance of laminated structural pier is improved to varying degrees.The optimum design of continuous rigid-structure bridge with super-high-piers of concrete filled steel tube(CFST)is carried out according to the range of parameters proposed,which can effectively improve the ductility performance of the super-qualified piers and reduce the peak structural response under rare earthquake.(3)Based on the seismic design method of reinforced concrete bridge and reinforced concrete-filled concrete laced high pier bridge,the design method of continuous rigid frame bridge with super-high pier suitable for engineering application is put forward,and the calculation formula of displacement adjustment coefficient Cd based on structural self-vibration period is given.The experimental results show that the proposed simplified seismic analysis method is in good agreement with the fiber model method.The research results of this paper can provide scientific basis and technical guidance for the formulation of relevant norms and engineering design,which is helpful to the popularization and application of this kind of new bridge structure in China,and has good social and economic benefits and broad industrial prospects.