Structural System Research Of Multi-tower Suspension Bridge

Multi-tower suspension bridge is a brand-new structural style of bridge. Compared to the traditional double-tower suspension bridge, it has more spanning capability. Therefore, the bridge of this type is always proposed in sea-crossing engineering when the strait is wide and deep. In this way, the construction amount of piers and foundations in the deep seawater can be greatly reduced, as well as the cost of the substructure. So doing some research on this type of bridge is quite necessary and meaningful. In this paper, a 3-tower suspension bridge is used as an example, and some primary research on structural system of multi-tower suspension bridge is performed. The works of the thesis will contain the following aspects:Firstly, the developing history of the traditional double-tower suspension bridge and the birth of the multi-tower suspension bridge are reviewed. Some multi-tower suspension bridge projects of some famous straits are introduced.Secondly, the static and dynamic characteristics of multi-tower suspension bridge are studied. The differences in structural characteristics between the traditional double-tower suspension bridge and the multi-tower one are analyzed. The change of structural characteristics with altering the number of towers in multi-tower suspension bridges is also discussed.Thirdly, the arrangements of spans and cables of multi-tower suspension bridge are studied. The effects of some important parameters to the static and dynamic characteristics are analyzed, such as main span length, span ratio of side-to-main, ratio of sag to span, cable spacing at the tower top. Furthermore, the advantages and disadvantages of some unconventional arrangement of cables are also discussed.Fourthly, the relative height of the center tower to the side ones and the structural form of the center tower are studied. The effects of some parameters to the static and dynamic characteristics are analyzed, such as flexural rigidity and torsional stiffness of the center tower, the height difference between the center tower and side ones.Finally, the differences in static and dynamic characteristics due to different bearing systems of the stiffening girder are studied. The merits and faults of each bearing system are generalized.