Design And Analysis Of Cable-Stayed Bridges With Unusual Shaped Single Pylon

As the symbol of cable-stayed bridges, the structure of pylons are various。 and unusual shaped pylons are used more widely, especially in city. But the internal forces of unusual shaped pylons are more complicated than usual pylons, which leads to the difficulty of calculation and analysis. The analysis was based on the preliminary design of cable-stayed bridge in 2nd Daxing Bridge in Ya’an. The spans of such bridge is divided into 50m+188m+122m+48m. A spindle shaped pylon with many crossbeams was designed. The finite element model involving beam elements of the entire bridge was established to analyze the static forces, stability, and earthquake-resistant performance and to optimize the design. To calculate and analyze the lateral internal forces of main girder, a solid model of the girder segment was established.Firstly, the application background, design theory and foreground of single pylon cable-stayed bridge were introduced. Then matters related to modeling of unusual shaped cable-stayed bridge were summarized. With the finite element model, stresses, deformation and stability of structure in construction and operation stages were calculated and analyzed, which came to the conclusion that the structures were safe and reliable. And the stability in construction stage decreased gradually. The effects of shrinkage and creep was also studied. A conclusion was drawn that the influences of time-varying effects of concrete in the studied case could not be ignored.Earthquake-resistant performance of the structures was analyzed with methods of response spectrum and time-history analysis. And capacity deficiency of the pylon was found in the action of earthquake. In order to solve this problem, dampers were set between the main girder and the piers. There was a decrease of about 20% in internal forces at the bottom of pylon and the displacement at the top of pylon. The effects of the earthquake action on pylon was reduced by the dampers.The solid model of the girder segment was established with the fern software ANSYS. The principal tensile stress was calculated and analyzed separately under the condition of different anchor position of prestressed tendons in the diaphragm. The effects of the diaphragm thickness was also studied. It showed that the changing of anchor position made a significant impact on the principal tensile stress. The principal tensile stress could be reduced by the way of adjusting anchor location as low as possible in the diaphragm.