Aerodynamic Force Characteristics and Equivalent Wind Loads of Cantilevered Gallery Bridges

Cantilevered gallery bridges feature non-uniform cross-sectional geometry along the span and pronounced bluff-body characteristics, yet their wind load characteristics remain insufficiently studied. Moreover, existing wind load calculation methods, which were primarily developed for conventional bridges or building structures, are of unclear applicability to this structural type. Taking a cantilevered gallery bridge as a case study, the static aerodynamic force coefficients and equivalent wind loads are systematically investigated through 2D and 3D CFD simulations and wind tunnel tests, and an equivalent wind load calculation method that explicitly accounts for the structural frequency-response characteristics is proposed. The results indicate that the commonly used CFD methods yield significantly distorted predictions of the static aerodynamic force coefficients for such non-uniform cross-sections. The sheltering and flow interference effects of the mountain significantly influence the variation patterns of the static aerodynamic force coefficients with wind direction. Both turbulence intensity and integral scale have greater amplifying effects on the vertical and torsional responses than on the lateral response, with turbulence intensity exerting a more pronounced influence. In terms of equivalent wind loads, the results obtained from the bridge design code are overly conservative, while those derived from the building design code by analogy with towering structures agree well with the test measurements. However, when the structure is treated as a high-rise building, the computed equivalent wind loads are substantially underestimated, indicating that the classification of such gallery bridges in building codes significantly affects the estimation of equivalent wind loads. The proposed equivalent wind load calculation method, based on the structural frequency-response characteristics, is theoretically independent of structural type classification and offers improved generalizability. It achieves high accuracy under the selected typical conditions, providing a feasible analytical tool for the equivalent wind load assessment of cantilevered gallery bridges.