Investigation of Spatial Coherences of Aerodynamic Loads on a Streamlined Bridge Deck in an Actively-Controlled Wind Tunnel

Abstract

Two-dimensional flow fields were simulated in an actively-controlled wind tunnel by using multiple fans and active-vibration grids. On coming flow features and aerodynamic loads on a streamlined bridge deck section model were measured simultaneously. Experimental result shows that the spatial coherences of on coming flows and aerodynamic loads are both influenced by on coming flow features. Longitudinal and vertical flow features have different effects on spatial coherence of aerodynamic loads. The shape of the spatial coherence function versus frequency curve does not always satisfy an exponential law, but sometimes shows an inverse form in the low-frequency region. A new empirical model is proposed and compared with the traditional exponential one. This new model shows good performance in reflecting spatial coherences of both oncoming flows and aerodynamic forces under different flow conditions.

Explicit polynomial regression models of wind characteristics and structural effects on a long‐span bridge utilizing onsite monitoring data

“…The existing theoretical analysis method uses the principle of aerodynamics, which is based on the theory of fluid mechanics and establishes a mathematical model of wind effects on the structure. The critical problems are to determine the aerodynamic admittance functions, which are proposed to modify the buffeting force model based on the quasi‐steady assumption 13 and to determine the spatial correlation of fluctuating load 14 . However, some recognition methods of aerodynamic admittance function are challengeable to be implemented in the laboratory and the aerodynamic admittance depends heavily on the incoming flow conditions and the types of the bridge section 15,16 .…”

Effect of Accessory Attachment on Static Coefficients in a Steel Box Girder for Long - Span Suspension Bridges

“…With a small slenderness ratio, this type of bridge girder is considered streamlined and semi-aerodynamic. Different from the blunt non-aerodynamic body, whose flow separations take place at the edges and corners, the streamlined body presents uncertain separation positions because of stream velocity, turbulence intensity, girder geometry, surface roughness, and so on [8], [9]. The natural frequencies of these bridges are significantly reduced; therefore, aero-elastic instabilities, such as flutter and vortex-induced vibration, are of the most considerable concern [10], [11].…”