Experimental determination of aerodynamic admittance functions of a bridge deck considering oscillation effect

Abstract

The effective aerodynamic shape of a bridge deck during a buffeting response can be modified relative to its original section in the stationary state, and the identification method for aerodynamic admittance functions (AAFs) of a bridge deck considering the oscillation effect is established based on wind tunnel tests in conjunction with theoretical analyses. The aerodynamic forces on a bridge deck strip and surrounding fluctuating wind speeds, as well as the response of the model in a turbulent flow, are measured simultaneously on a stochastic vibrating spring-suspended sectional model (SSSM). A new method is proposed to separate the aerodynamic forces on the bridge deck strip into self-excited and buffeting force components. The AAFs with respect to longitudinal and vertical turbulence components are then identified according to the extracted buffeting forces and measured fluctuating wind speeds via a colligated least square method (CLSM). The approach is validated experimentally on a closed-box bridge deck strip using force-balance measurements, but it can be applied to bridge decks of any cross-section. The bridge deck AAF is confirmed to depend on its oscillation state, and the wind tunnel test for the identification of bridge deck AAFs was carried out in the oscillating state for high accuracy.