Aeroelastic Model Test Study on A Bridge Pylon Considering the Interference Effects of Surrounding Structures

The interference effect between buildings has been a popular issue in structural wind engineering for a long time. Most researches about this issue have been focused mainly on high-rise buildings. For long-span bridges, the interference effects between structures are rarely discussed. In this paper, an aerodynamic elastic model test of a free-standing bridge pylon located adjacent to two large-scale cooling towers is presented. Through the mode analysis, the structure mode shapes are obtained. Then by the simulation of the two cooling towers in the boundary layer during the aeroelastic model test, the vibration responses of the bridge pylon in smooth and turbulence flows are obtained respectively. The study shows that the interference effect of the two huge-volume cooling towers on the wind induced vibration responses of the bridge pylon should not be neglected. In smooth flow, due to the regular shedding vortex from the upwind cooling towers, the interference effect is evident in that strong resonant responses are induced on the lower-order modes of the downwind bridge pylon. However, in turbulence flow, this kind of interference effect is greatly reduced. Moreover, more attention should be paid to the case when the cooling towers are located at the perfectly right upwind direction of the bridge pylon. Their interference effect will certainly cause great resonant vibrations in the longitudinal direction, which cannot be ignored for granted. Furthermore, the turbulence flow at the bridge pylon considering the interference effect is measured through a 1:500 flow experiment to discover the interference effect of the cooling towers. In the end, a dynamic magnification factor is proposed to take the interference effect into consideration, with a value of 2.25 suggested for the design of pylons.