The Effect of Variation in the Interlayer Spacing of a Double‐Layer Truss Bridge on the Bridge Deck Wind Environment

Double‐layer truss bridges are widely used in long‐span crossings due to their high load‐carrying capacity and structural efficiency. However, their complex truss configurations significantly alter the wind field around the deck, posing potential challenges to driving safety and comfort. To investigate key controllable design parameters for the deck wind environment, this study employs computational fluid dynamics (CFD) to systematically analyze the impact of varying the interlayer spacing between the upper and lower decks on the wind environment at vehicular height. By examining wind profiles and equivalent wind speeds under various combinations of interlayer spacing and wind angles of attack (AoAs), the results reveal that the wind environment on the upper deck is less affected by changes in interlayer spacing. However, its equivalent wind speed exhibits a stable negative linear correlation with spacing under negative AoAs. In contrast, the lower deck wind environment is highly sensitive to interlayer spacing variations, with its equivalent wind speed exhibiting a positive linear correlation with spacing at positive AoAs and a negative linear correlation at negative AoAs. Mechanistic analysis indicates that modifying the interlayer spacing directly influences the airflow passage between the decks and web members, thereby affecting the development space and interference level of the incoming wind and ultimately determining the wind field characteristics at driving height. This study identifies interlayer spacing as a critical design parameter for controlling the deck wind environment in double‐layer truss bridges, providing a theoretical basis and practical guidance for optimizing the wind‐resistant design and enhancing traffic safety and comfort.