Comparative analysis of bridge cables with concave fillets

In this paper the aerodynamic performance of two new cable surfaces with concave fillets are examined and compared to cables with traditional helically filleted, plain and pattern indented surfaces. To this end, an extensive wind-tunnel campaign was undertaken to measure the aerodynamic static force coefficients up to the super-critical Reynolds number range and rain-rivulet suppression ability. Flow visualizations tests were performed to better understand the structure and development of the wake. Both innovations outperform traditional surfaces in terms of rain-rivulet suppression thanks to the ability of the concave shaped fillet to act as a ramp for the incoming rain-rivulet. Furthermore both innovations are able to suppress vortex shedding at low Reynolds numbers, in contrast to the other cable surfaces tested. Moreover the innovation with the staggered surface shows an early reduction of the drag force while maintaining a zero lift up to the super-critical range.