The Construction Of Concrete Cable Bent Tower And Design & Computation Of Crossbeam Bracing Structure Of The Long-Span Bridge

In the last ten years, a great achievement has been achieved in the construction of long-span bridges in China. The concrete cable bent tower is used widely in long-span bridges. However, it's difficult to set the equipment into the site and manage the construction. The tower shafts, most of which are hollow and varying in cross section, and altitudinal construction bring trouble to the form work and the stress of strand wire. And the cracks on the crossbeams will be caused by the following - deformation of the bracing structure joints, elastic deformation,uneven settlement and temperature changes. The additional stress of the base slab and the foundation is caused by the deviation of cable bent tower construction. The wind-induced vibration of the uncompleted suspended structure will exert negative effects on the safety and the quality. The large volume of the solid tower shaft easily causes cracks. So the construction of the concrete cable bent tower becomes one of the key technologies in the construction of long-span bridges. It is necessary to study the construction technology of concrete cable bent towers.The dissertation introduces construction sequence, construction methods (supporter construction, slip-form construction, climbing formwork and turn-over formwork construction), anti-overturning measures of the tilted tower, crossbeams' construction and its bracing structure. On the base of the link ways of each member joint, the dissertation also puts forth a method to simplify the crossbeam bracing structure into spatial truss,spatial stiff frame and spatial combined structure. It presents the computation models of different construction conditions, based on construction sequence and technologies.Generally speaking, with the property of easily achieving automatic computation, the displacement method is applied more widely. The dissertation discusses some theories of computation including the unit stiff matrix of the spatial member in the local coordinates,the coordinate transformation, the integration of the integer stiff matrix,the equivalent joint load,the introduction of the boundary condition,the computation of the unit internal force and support reaction,the stableness of the spatial stiff frame. The dissertation also discusses the methods of dealing with several unusual problems such as combined structure, temperature stress,elastic bearing. Finally, based on the structure of the south cable bent tower and the construction technology of the JiangYin Bridge, the computation of the bridge's crossbeam bracing structure is carried out and an analysis of the computation's results is also made.