Horizontal wind loads for stability design of large duo-pitch multi-span greenhouses

Wind loads are responsible for a large amount of damage to greenhouses, and are therefore an important factor in the structural design of greenhouses. Previous wind load studies on greenhouses [1-8], have only investigated wind loads on the first 9 roof spans. However, most greenhouses are much larger than 10 roof spans. For these larger structures, the contribution of the roof to the overall wind force is more significant. For a safe and economic design, a detailed assessment of the wind loads on the roof beyond 9 spans is needed. An atmospheric boundary layer wind tunnel study was performed to determine the overall horizontal wind load on multi-span duo-pitch greenhouses. Static force measurements were made on 9 models with multi-span duo-pitch roofs varying between 10 and 90 roof spans. Additionally, surface pressure measurements were performed on a 30-span model. Experiments were done with two different roughness types on the turntable. One set of static force measurements was performed with a smooth turntable, illustrated in Figure 1(a). In the second set of static force measurements and pressure measurements, the rough carpet was extended onto the turntable, illustrated in Figure 1(b). More details of the experiment setup are given in [9]