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.
<p>Technological developments and innovative design techniques allow designers to create buildings and structures as true art expressions. Then structural engineers often have to afford and tackle problems, which are not covered by the codes; nevertheless, a satisfactory level of safety must be ensured, so that ad-hoc analysis and models have to be used.<p> In the paper, a wind tunnel test campaign about the new Congress Center in the EUR district at Rome is presented. The building, designed by Italian architect Massimiliano Fuksas, looks like a translucent container (about 70 meters by 170 meters in plan and 40 metres in height), with steel bearing structure and glass facades.<p> In particular, the longitudinal fronts are double-skin facades: only the outer skin has permanent openings, while the interior one can be completely closed. Inside this shell, a “cloud” of 3500 m², made out of a steel structure and Teflon cover, will contain a concert hall (auditorium) with 1800 seats.<p> Wind tunnel tests have allowed to optimize the design of both window glasses and structures supporting them, with a significant cost sparing effect. A particular attention has been paid in the analysis of the internal pressure in different configurations; as a matter of fact, the external facades present many openings (doors and windows) which can let alternatively consider the building as permeable or impermeable to the wind. The investigations have also permitted to establish the presence of internal flows involving the structure supporting the Teflon covering of the cloud.</p>
<p>In order to optimize the structural design of buildings it is often convenient to recur to wind tunnel tests on scaled models, including loads and pressure measurements. While performing pressure measurements models have to be equipped with a limited number of sensors; one of the problems to be faced during the setting-up of the tests is to determine the optimal number and placement of the pressure taps.</p><p>It is proposed a method that uses statistical techniques able to reconstruct the pressure time histories in real scale, in the zones between the investigated positions. Finally the optimal number and position of the measuring points is analyzed by means of a technique based on neural networks.</p>
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