Sheltering efficiency of wind barriers on bridges

Abstract

a b s t r a c tSheltering efficiency of wind barriers on viaducts was experimentally studied in a boundary layer wind tunnel. Effects of wind incidence angle on flow field characteristics in the wake of a wind barrier were reported. Mean velocity fields and vorticity fields were determined using the Particle Image Velocimetry (PIV) technique. Freestream velocities were measured using hot-wire and Pitot tube. Results indicate a possibility of wind-induced instability of high-sided vehicles at larger vertical incidence angles, especially in the traffic lane close to trailing edge of the bridge, as velocity fluctuations and mean freestream velocities approach the road surface when increasing the vertical incidence angle. Removing elements from the wind barrier causes very large local velocities immediately downstream from a barrier and strong vorticity in the entire area in the wake of a wind barrier. Variations in horizontal incidence angle do not seem to affect flow field characteristics significantly. Without a wind barrier, wind velocities on bridges reach 80% of the freestream velocity at height as low as 1 m full-scale along with very strong vorticity in the immediate vicinity of the road surface.

Transient cross-wind aerodynamic loads on a generic vehicle due to bora gusts

“…Wang et al (2007) designed a wind barrier to reduce wind velocities on the Hangzhou Bay Bridge in China. Effects of the wind barrier porosity, height and orientation on their sheltering efficiency for vehicles on bridges were reported in Procino et al (2008), Kozmar et al (2009aKozmar et al ( , 2009bKozmar et al ( , 2012.…”

“…Nevertheless, it would be advantageous to carry out tests described in this study at larger Reynolds numbers in the future. Furthermore, as wind barriers largely determine flow characteristics on bridges, a series of experiments was previously carried out both on bridges with and without barriers in order to determine flow conditions as influenced by the wind barrier height, porosity, geometry, as well as wind incidence angle and atmospheric turbulence (Kozmar et al, 2009a(Kozmar et al, , 2009b(Kozmar et al, , 2012Procino et al, 2008).…”

Effects of wind barrier on the safety of vehicles driven on bridges

“…Considering the sudden change of the aerodynamic forces on road vehicles, Charuvisit et al (2004) analyzed the aerodynamic coefficients of vehicles in the wind tunnel test under the conditions of considering or neglecting the wind barriers as vehicles approach the bridge towers. Kozmar et al (2012) paid great attention to the mean velocity field and turbulence structure behind the wind barrier on the bridge and concluded that wind barrier greatly reduced the mean velocity of the incoming wind. Further, Chu et al (2013) analyzed the influence of wind barriers on the aerodynamic coefficients of vehicles.…”

“…The wind barriers in actual bridges should be adopted according to the safety of vehicle crossing the bridge. The evaluation of the sheltering efficiency of wind barriers, depending on the aerodynamic coefficients of vehicles (Argentini et al, 2011;Charuvisit et al, 2004;Chu et al, 2013) and the flow field above bridge deck (Kozmar et al, 2012), is still far from perfect. In the present study, the aerodynamic coefficients of high-sided vehicles (commercial van and articulated lorry) are firstly obtained by a large scale section model in the wind tunnel.…”

Fluid-structure interaction in long-span bridges

“…Procino [127,128] and coworkers studied the influence of barrier porosity in the flow condition on the bridge deck, but did not study the influence on the stability. Larsen [108], in a paper studying the shape of bridge decks, concluded that Jersey type barriers, or porous barriers covered by snow can lead to the instability of an otherwise stable bridge.…”