Studies On New Cable Supported Bridges Structure System

In the process of build in the city, cable supported bridges has encountered many difficult issues, such as cable-stayed bridge tower is too high, suspension bridge need to build expensive anchorage and so on. Therefore, the bridge structure system and the construction techniques urgent need innovative. In this paper, self-anchored cable-stayed suspension combined bridge, a new structural system, is put forward, it will solve the above problems.From the design, construction, static analysis and dynamic analysis, the self-anchored cable-stayed suspension combined bridge has been study in this paper. The conclusion is the new structure is feasibility and rationality, the advantage of it is more apparent than other similar bridges such as self-anchored suspension bridge.In this paper, the special construction methods for self-anchored cable-stayed suspension combined bridge are put forward, they are greatly reducing the cost of temporary facilities. The road anchorage, temporary cable and other innovative construction techniques can solve the difficult problems in the construction, but also open up the idea of construction of similar bridges.Through theoretical analysis, the suitable calculation for the self-anchored cable-stayed suspension combined bridge is founded. In the preliminary analysis, every span can use the traditional theory make a separate analysis and finally adjust the entire structure. In the accurate structural analysis, it can be calculated using the finite element method. After analysis, profit from the restraint of the slings and the cable, the main cable, hanger and the stiffening girder of the self-anchored cable-stayed suspension combined bridge form a self-balancing system, the overall instability does not occur. Therefore the design can not view the stiffening girder as a simple stiffening bending structure, that will increase the cross section and result in material waste. In this paper, the design model of the self-anchored cable-stayed suspension combined bridge is discussed from the general to the details, and then a finite element model is established in the ANSYS. Because the gravity of main cable is very smaller than the gravity of main beam, the cable shape is very close to parabolic. Besides, the finite element models of a Cable-stayed bridge and a self-anchored suspension bridge are established in the paper.Through the static analysis, the self-anchored cable-stayed suspension combined bridge is good in performance. To the present model in this paper, the limit span of main span is to 768.2m,the ultimate bearing capacity of the model is up to 10.6 times than the live load.In the modal analysis, the first vibration mode of the three models are all vertical floating, the reason is they are all adopt a float system, the main beam is not limit in vertical. The frequency of the vibration mode of the three models is directly affected by the system stiffness, the main beam material and other factors. Because the frequency of the torsion is high, the wind stability is good.After the earthquake time history analysis and the response spectrum analysis, the Seismic performance of self-anchored cable-stayed suspension combined bridge is good, the system deformation and internal forces of each component are in the permit range. Except the displacement and the moment of tower have a great difference for the seismic spectrum of the two method are different, the internal forces and deformation of other components are more uniform, and then the two methods are verified with each other.