Abstract
During the construction of high composite steel-tube reinforced concrete bridge piers, the steel circular cylinders in a group are exposed to wind for a certain period. Under wind flow, the grouped cylinders have extremely complicated aerodynamic characteristics such as switching of the flow and mutual interference of vortex generation. In order to establish a rational wind resistant design for this type of structures, the aerostatic characteristics of a group of 9 cylinders (3 × 3) were extensively studied in a series of wind tunnel experiments under uniform as well as turbulent flows. As a result of the experiment, it is found that:
(1) The drag coefficient that acts on the group is smaller than the one established according to present design standards and individual drag coefficients corresponding to each of the cylinders in the group are different.
(2) For intervals of the cylinder group varying between 1.4-2.0 times the cylinder diameter, lift characteristics experience significant changes. In particular, the lift force reverses its direction for cylinder intervals of 1.4 times the diameter and 1.8 times the diameter and above.
(3) Moment coefficients increase inversely with cylinder spacing and proportionally with turbulence intensity.
