Internal Force Analysis On The Main Girder Of MaYang Low Tower Cable-Stayed Bridge

Extradossed Bridge has great superiorities in the program selection for bridges which has the span from100m to300m, this is mainly due to its innovative design and reasonable structure by force. In recent years, this type of bridge has been widely promoted in China. This paper has been written in the engineering background of Ma Yang curve-outward extradossed cable-stayed solution, the internal force of Ma Yang Bridge has been analysed through the establishment of the finite element model and solid truss models.Introducing the bridge-type programs, bridge layout and program ideas of Ma Yang Bridge, proposing the establishment of bridge-type optimization model which based on two-stage fuzzy principle counter preferred schemes for bridge-type which includes qualitative indicators. The establishing process of he preferred model has been introduced in details. Then applying this model to the optimal method of Ma Yang Bridge-type program. The result shows that low tower cable-stayed bridge is the preferred program.Briefly introducing the simulation of the main structure of the bridge model, the finite element model of Ma Yang Bridge has been established based on the finite element theory. Using the unknown load factors function which based on the influence matrix to solve the rough cable force of the bridge, then applying the tune cable features to do further optimization of the cable tension, so geetting a more reasonable group of making bridge cable force. Using different lengths of no cable zones and the hight of tower to establish the finite element model, then studying the changes of internal forces in Ma Yang Bridge. The lengths of no cable zones of tower root and side support have different affect on the internal forces of the main girder. Tower height can be adjusted to improve the force of main beam and reduce deflection of the main beam.Analysing the internal force characteristics of the main beam when the Ma Yang Bridge is in states of largest cantilever and making bridge. Obtaining the internal forces variation of main beam is similar in the two states. Girder internal force peaks are always located at girder unit around the main tower. Using shear lag to describe the shear lag effect of the main beam, studying the shear lag effect of the main beam when the Ma Yang Bridge is under constant loads and considering the nonlinearity of materials. After considering material nonlinearity of shear lag effect is more uniform than that under the elastic state.Analysing the local stress of anchorage zones in Ma Yang Bridge. There is complex stress concentration at anchorage zones, raising some suggestions to improve concentration of stress.