Influence of Ultra-high Piers on Mechanical Response of Three-pylon Cable-stayed Bridge in Mountain Area

Abstract:

The multi-pylon cable-stayed bridge is a feasible scheme for spanning wide rivers and valleys. However, the ultra-high piers of multi-pylon cable-stayed bridges in mountainous areas can decrease the overall stiffness of the bridge structure, which makes its mechanical response different from those of ordinary multi-pylon cable-stayed bridges. To study the influence of ultra-high piers on the mechanical behaviour of three-pylon cable-stayed bridge in deep and wide valleys, a typical three-pylon cable-stayed bridge under construction is taken as an example. The index and calculation method for mechanical response are firstly established. Then, the effects of the pier height, pier height difference and stiffness of girder and pylon on the displacement at the top of the pylon, bending moment at the bottom of the pier and deflection at the mid-span are analyzed. The results show that: when the pier height increases, the additional bending moment at the bottom of the pier caused by the traffic lane load and the temperature decreases while longitudinal displacement at the top of the pylon and deflection at the mid-span of the girder increase; the difference of the pier height has a great influence on the internal force of the pier and the lower pier will bear more bending moment; the structural displacement can be better controlled by increasing the stiffness of the pylon.