Analysis Of Static And Dynamic Features Of Three-tower Suspension Bridge Structural System

As the transportation of China develop in these years, an umber of long-span bridges are built to meet the demands of traffic layout. Because of their long span ability and light and beautiful structure, suspension bridges are more competitive bridge type of long-span bridge. And with the development of bridge construction technique, the span of birdge become more longer. To across the wider water area or fit the special topographical environment condition, a new system of suspension birdge with multi-tower and multi-span was proposed, and the three-tower suspension bridge program was especially recommended by the bridge engineers. The three-tower suspension bridge is a new structure type, its static and dynamic behaviour and different structural systems selection with different lengthways and vertical restraints need to be analyzed and studied deeply.Firstly, the thesis birefly introduced the current development of suspension bridges and multi-tower suspension bridges and there mechanics performance. Then describes the geometric nonlinear effects and treatment of suspension bridge and systematically expounded the basic theory of static and dynamic analysis of suspension bridge structure: linear-elastic theory, geometric non-linear deflection theory, geometric theory of nonlinear discrete-boom and the geometric nonlinear finite element theory.In this thesis, a spatial finite element model of a three-tower suspension bridge which is named M was established by large-scale professional finite element software MIDAS/Civil 2006, and its initial equilibrium state and static structure analysis was carried out.Different structural systems with different lengthways and vertical restraints of three-tower suspension bridge have a greater influence for the stresses and deformation of bridges. In this paper, different spatial finite element model of different lengthways and vertical restraints was established by MIDAS/Civil 2006 software, and the static and dynamic behaviour of different model were analyzed and compared. Some suggestions on the three-tower suspension bridge system was given, and can be used as references for future similar design: (1) Setting lengthways restraints at the middle tower is better, setting central buckle between the main cable and the stiffening beam need to be carefully designed, setting lengthways restraints at all the three towers is unnecessary. (2) It is suitable that continuous stiffening beam is fixed with the middle tower if the stiffening beam can meet the stress requirements. (3) When the stiffening beam design is limited, the vertical constraints at the middle tower is unnecessary.