Experimental Study On Aerodynamic Characteristics Of Special-shaped Landscape Bridge

The design of landscape bridge built to facilitate tourists always pursues novel structure and unique shape,so more and more special-shaped landscape bridges appear.Due to the diversity of cross-section and spatial arrangement of bridge components,flow around the special-shaped landscape bridges will show a very complex three-dimensional effect,which is bad for the wind-resistance design of the bridge.It is of great value to accurately understand the aerodynamic characteristics of the special-shaped landscape bridge for its wind-resistance design.Taking a special-shaped landscape bridge in China as the engineering background,the aerodynamic characteristics of the bridge are tested and studied by rigid model pressure measurement test of overall bridge.The main work and conclusions are as follows:(1)The rigid model of the overall bridge was designed and made strictly according to the aerodynamic shape of the original landscape bridge.The aerodynamic force coefficients of a curved variable cross-section girder with awning and an inclined variable cross-section bridge tower with a sightseeing platform were tested.The results show that the aerodynamic coefficients of the girder and the awning reach the maximum near the direction of the orthogonal wind,and the maximum drag,lift,and torque coefficients of the girder are around 1.0,0.3,and 0.12,respectively.The maximum lift and torque coefficients of the awning are around 0.7and 0.5,respectively.The aerodynamic forces subjected to girder and awning are in the same direction at most incidence angles.Aerodynamic interference of the girder and the sightseeing platform will reduce the local aerodynamic coefficient of the pylon.The aerodynamic force coefficients of the sightseeing platform along the bridge and across the bridge reach the maximum near α=180°(opposite inclined direction of the pylon flow)and α=110°,respectively,and values are all about 0.9.(2)The aerodynamic force coefficients and Strouhal number of the pylon at different inclined angles are tested,and the effect of the inclined angle on the aerodynamic characteristics of the pylon is studied.The results indicate that under the influence of the tilt of the pylon,the drag coefficient near α=0°(inclined direction of the pylon flow)and the lift and torque coefficients near α=30° decrease gradually with an increasing height of the pylon.The drag coefficient near α=180°(opposite inclined direction of the pylon flow)and the lift and torque coefficients near α=140°increase gradually with an increasing height of the pylon.The distinction of aerodynamic force coefficients at different heights of the pylon becomes weaker with the decrease of inclined angle.The Strouhal numbers of the pylon are around 0.11 near α=0°and 0.15 near α=120°(the flow direction is perpendicular to the waist of the isosceles trapezoid section).The increase of inclined angle makes the vortex shedding of the bridge tower gradually become inconspicuous.