The Construction Control Simulation Calculation Of Higher-Lower Tower Cable-Stayed Bridge

Double X-arch bridge, is one of the new arch bridge types.This type of bridge is of novelty style with complex constitution and distinct spatial mechanics effect, and the research outcome about the double X-arch bridge has only a few in our country and overseas. Therefore, conducting the analyses of double X-arch bridges' mechanical properties takes on its important theoretical senses and practical values.In this dissertation, the main bridge of Zhanhe bridge over Chengdong River in Pingdingshan City, a double X-arch bridge is discretized by the FEM according to its structural characteristics with the spatial beam element simulating the longitudinal tied beams,end floor beams, middle floor beams, axch ribs and the like, and with the plate element simulating the bridge deck, and with the truss element simulating the suspenders to erect the bridge's spatial mechanical computational finite element model. Suspenders' initial force is calculated by influence matrix method and optimized, which make the computed results of suspenders' responsive internal force, main structures' internal force and deformation consistent with the data of design; Finite element software ANSYS special for bridges' structure analyses was applied for analyses of this double X-arch bridge's mechanical properties of the static state, dynamic characteristics and stability on the initial equilibrium configuration, and the design of this double X-arch bridge was checked up in its completed stage. Moreover, the influences that the damage of the suspenders has brought on to this type of bridge's mechanical properties of the static state, dynamic characteristics and stability are discussed. Summarizing above work, this dissertation arrived at some conclusions as follows:(1) The internal forces of arch ribs and longitudinal tied beams are in symmetry of the span centre. The axial forces and shearing forces and moments of longitudinal tied beams have sudden changes in the position of suspenders; the shearing forces of arch ribs also have sudden changes in the position of suspenders, but the moments &axial forces of arch ribs have no conspicuous changes. For the constrained action of end floor beams, the moment diagrams of longitudinal tied beams resemble like that of continuous beams with the full cross-section compressing except the under brim of span center cross-section with a little tension stress, whose stress still meet the require of A-type prestressed units. The internal forces of arch ribs give priority to compression force by contrast with shearing forces&moments within plane. Arch ribs of the bridge also bear great out-plane moments, which indicate double X-arch bridge has obvious spatial effect in mechanical properties.(2) Internal forces of suspenders are in symmetry of the span centre and tension values of the suspenders are also relatively even. The safety factors of suspenders under eachconsidered load case in static state, with safety factor3.38 of inside suspenders and with minimum safety factor3.09 of outboard suspenders, which meet the requires in bridge design codes of large than 2.5 and have a comfortable margin.(3) The vertical displacement plays a dominant role in the integral deformation of this bridge and greater transverse displacement happens in the vault of arch ribs. In each considered load case in static state, the maximal vertical displacement of tied beams is -0.0283m, the maximal vertical and transverse displacement of arch ribs is -0.0337m and0.1m. The deformation of each members of this bridge in each considered load case are within the specialized range of bridge design codes, so that the deformation of each members of this bridge fulfils the deformation require of Serviceability limit-State.(4) The bridge's 1 St order stability factors under considered cases are between 7.975 and8.67, which meet the require of large than 4and indicate the bridge has highly stability,the bridge's 1 St order buckling modes are all out-plane torsional buckling modes of compositearches which indicates the arches' stiffness out of plane is relatively smaller than that in plane and controls the stability of the bridge. The bridge's vertical buckling and the deck system's transverse buckling appear in the high order buckling modes, which indicates that the bridge's vertical stiffness and the deck system's transverse stiffness are much larger than the transverse and torsional stiffness of the composite arches.