Influence of reduced drag load on stay cables on the construction cost of cable-stayed bridges: Two study cases

Abstract

Rain–wind–induced vibrations (RWIVs) can cause the large-amplitude vibration of flexible cables in cable-stayed bridges; such vibration is one of the engineering safety problems that must be resolved. Currently, aerodynamic measures, such as dimples and spirals, are typically used as measures for suppressing vibration in stay cables. By calculating and comparing the equivalent static wind loads (ESWLs) of six typical cable-stayed bridges, the proportion of ESWL acting on the cable to that acting on the entire bridge increases approximately linearly with the bridge span. Hydrophobic coating can effectively suppress RWIVs and evidently relieve the ESWL. Hence, compared with the commonly used aerodynamic measures with surface roughness, this coating has a considerable potential as an alternative for suppressing vibration. Based on the foregoing, the wind resistance design optimization of two actual cable-stayed bridges with main spans of 420 and 1160 m is implemented to investigate the construction costs of cable wind load reduction. After optimization, the structural responses of the main towers are reduced by 4%–12%, and the optimized tower and foundation sizes are reduced by 5%–8%. The optimization for the two bridges exceed 5% and 7%, respectively. The construction investment savings are approximately 2.3 million and 7.2 million USD, respectively. These values further improve with increasing bridge span and design wind speed.