Wind forces on porous elevated panels

Agricultural nets are used in fruit and ornamentals production as covering material in various light structures such as anti-hail and/or anti-frost shields, windbreaks, and coverings of shading or anti-insect structures. There is limited information in the existing standards for the calculation of wind loads on structures with permeable cladding like nets. Moreover, there are few experimental data concerning the wind pressure distribution around air permeable structures. For this reason, the wind-pressure distributions over permeable claddings need to be systematically investigated by field experiments and numerical simulations. In the present work, special full-scale field tests were designed and carried out to measure the wind pressures on experimental scale panels covered by various types of nets and by film. The film covering was functioning as impermeable reference material, for comparative purposes. The forces were measured at a central independent segment of the panel suspended on specially designed spring units by using displacement transducers. The measurements were compared to data obtained from a similar structure covered with impermeable plastic film and against the provisions of relevant standards. The full scale measurements were also compared to computational results obtained by CFD simulations.