Spanwise layout optimization of segmented bridge wind fairings: Experimental validation using aeroelastic strip models

Long-span bridges with Π-shaped girders are highly susceptible to vortex-induced vibration (VIV). Conventional full-span aerodynamic countermeasures are often material-intensive, inefficient, and costly. This paper proposes a spanwise layout optimization method for identifying optimal segmented wind-fairing installation zones and the minimum required installation length. A modal energy control ratio is defined, and a zero-total-damping criterion is adopted to determine the critical condition for VIV suppression. Wind tunnel tests on a 1:70-scale aeroelastic strip model were conducted to validate the proposed spanwise method for segmented fairings. The first four vertical bending modes and their corresponding VIV responses were measured experimentally. The results show good agreement between the measured and theoretical layout lengths. Local segmented fairings effectively suppress VIV, achieving the same suppression performance as full-span layouts while reducing material consumption up to 77.5%. This study provides an economical and efficient aerodynamic control alternative for long-span Π-shaped girder bridges.