Effect of corner modifications on galloping-induced response and galloping force of 3:2 rectangular section

Corner modifications play a significant role in influencing the galloping instability of rectangular sections, as highlighted in prior aerodynamic studies. This research focuses on the effects of various notched and chamfered corner modifications on the galloping behavior of a rectangular section with a side ratio of 3:2, offering a novel perspective by examining these modifications from an aeroelastic force standpoint. Wind tunnel experiments were conducted to simultaneously measure the galloping forces and displacements of the section under uniform flow. The results reveal that, similar to sharp-corner rectangular sections, the onset wind velocities of modified-corner sections deviate from the quasi-steady critical wind velocities for galloping and instead align with those associated with vortex-induced resonance. Among the modifications, notched corners are shown to be more effective than chamfered corners in reducing galloping amplitudes, with smaller notches significantly diminishing amplitudes and larger notches completely suppressing galloping divergence. Using a robust mathematical model for galloping forces, the underlying mechanism of the suppression effect due to corner modifications is elucidated. The superior suppression effect of notched corners, compared to chamfered corners, is attributed to their greater influence on high-order aerodynamic damping. This study extends previous findings by emphasizing the differences between sharp-corner and corner-modified rectangular sections, providing new insights into galloping mitigation strategies.