Aerodynamic behaviour of an inclined circular cylinder

A unified approach to aerodynamic damping and drag/lift instabilities, and its application to dry inclined cable galloping

“…The theoretical aerodynamic damping for these values was À0.44%. However, the actual structural damping of the dynamic model, for low amplitude vibrations, was only approximately 0.03% (Cheng et al, 2003a). According to Fig.…”

“…Darker shading indicates lower (or more negative) values. To relate the values of the nondimensional parameters to a typical bridge cable in air, the values for the dynamic cable tests (Cheng et al, 2003a) are used as an example. For the cable diameter of 160 mm, Re ¼ 3 Â 10 5 corresponds to a wind speed of 28 m/s, and for the cable mass per unit length of 60.8 kg/m and natural frequency 1.4 Hz, Z a ¼ 1.0 Â 10 4 corresponds to an aerodynamic damping ratio of 0.22%.…”

“…A particular case of interest is a ¼ 54:71, which corresponds to the test of the dynamic cable model that exhibited divergent amplitude vibrations [set-up 2C, Cheng et al (2003a)]. The calculated values of the aerodynamic damping parameter, based on the static model test data, are shown in Fig.…”

“…The dynamic cable tests (Cheng et al, 2003a) were only performed at the specific cable-wind angles f ¼ 351, 451 and 601, whereas the static cylinder pressure measurement tests (Larose et al, 2003) covered cable-wind angles fX54:71. Hence direct comparisons could only be made for f ¼ 601.…”

“…More extensive wind tunnel tests have only recently been conducted on inclined circular cylinders at the National Research Council Canada (NRC), in collaboration with RWDI Inc. and the University of Ottawa. Firstly, a series of tests were conducted on a full-scale cable section elastically supported to simulate the dynamics of an inclined cable (Cheng et al, 2003a). One particular configuration, designated set-up 2C, exhibited divergent amplitude vibrations at a wind speed of 32 m/s.…”