Ultra-low frequency vibration and noise control of a highway suspension bridge based on periodic structural band gap characteristics

Long-span river-crossing bridges, while enhancing regional connectivity, generate low-frequency underwater vibrations and noise due to vehicular traffic, which negatively impacts the aquatic environment and organisms. To address this, a novel method for controlling ultra-low frequency vibration and noise of a long-span suspension bridge is proposed, based on the bandgap characteristics of periodic structures. Through theoretical analysis, parametric optimization, and numerical simulations, the optimized bandgap ranges are determined as 2.92-5.18 Hz for periodic pile rows and 2.81-6.71 Hz for the tower's phononic crystal structure, effectively covering the dominant vibration frequencies of both the bridge tower and surrounding soil. Furthermore, a vibro-acoustic coupling model is established to validate the effectiveness and feasibility of the proposed method, and the results show that this new method can achieve the maximum vibration and noise reduction of 13 dB. This research provides a new approach and theoretical framework for controlling ultra-low-frequency underwater noise and vibrations in longspan bridges, contributing to aquatic ecosystem preservation and sustainable infrastructure development.