Aerodynamic characteristics of a train on a long-span bridge with steel truss section under crosswinds

Abstract

An experimental-numerical methodology was performed to investigate the aerodynamic characteristics of train vehicles on a truss bridge under crosswinds and the flow field around. Taking a long-span cable-stayed bridge with three main trusses as the engineering background, a wind tunnel test was carried out on a 1:80 scale model under different deck cross-section shapes, vehicle positions, and wind-attack angles. A three-dimensional CFD model was further established to explore the distribution of the flow speed inside the complex truss structure. The results show that when the train moves from the box deck to the truss deck, both the mean and RMS values of the pressure coefficients on the vehicle surface are greatly reduced. The maximum surface pressure coefficient occur when the vehicle is located at the track just behind the middle truss plane. The flow field inside the three-main-truss structure is notably uneven. The average equivalent wind speed is much lower than the oncoming crosswind speed. However, the maximum crosswind reduction coefficient reaches 0.92 occurring near the triangle center of the leeward truss panel. In addition, higher winds occur at 0.25 times the truss height above each track, which is consistent with the height of the center of the vehicle body.