Articles
STANDARD FOR FILM-COVERED GREENHOUSES
At the same time there is an increase in damage (mostly winddamage) with this type of plastic greenhouses.
The Dutch Standard for greenhouses NEN 3859 [1] has been developed mostly for glass-covered greenhouses.
Therefore there is a need to develop a special Standard for film-covered greenhouses.
One reason for this is the fact that specific structures and details for synthetic film-houses occur such as curved tubes and clamping connections, which are not common in glass-covered greenhouses.
Also the wind and snow loads are different for the tunnel-type of greenhouses compared with greenhouses with saddle-roofs.
The Code of Practice NPR 3860 [2] gave already the first rules according to windloads on tunnels.
The drafting of the Standard aims at reducing the occurrence of damage to greenhouses caused by wind, snow or other loads.
Therefore the special Standard gives calculation-rules, among other things for wind- and snowload and describes the requirements for the structure-profiles, the connections, the foundation, the stability-bracings and the fastening of the plastic films.
The IMAG, Wageningen has made a first draft of this specific Standard.
The results of the calculations of the structure of a number of tunnels, according to the proposed Standard will also be presented in this paper as an example.