Numerical estimation of pressure coefficients over single and multispan duo pitched roof greenhouses
2012
Kateris, D.L. | Kotsopoulos, T.A. | Fragos, V.P. | Nikita-Martozopoulou, Ch
The greenhouses have usually metal frame covered by glass or plastics and therefore are light structures, which make them sensitive to dynamic loads such as the wind load. The air flow over a greenhouse is a complex phenomenon. The pressure coefficients are used to calculate the wind load on the building’s roof. Although, the eurocode for wind actions EN 13031-1:2001 gives values for external pressure coefficients on the greenhouses, many manufacturers complain for these values because they lead to heavy structures of greenhouses with high construction costs. The proper design of the greenhouses would have to ensure not only the functionality and the static safety of the structure but also to keep the construction cost at low level. In the light of the above and taking into consideration that the adjustment of national regulations to eurocode is expected to be completed in 2011, the present work is focused on the calculation of the pressure coefficients on single and multispan duo pitched roof greenhouses. The study of an incompressible two-dimensional, steady, viscous air flow takes place in a hypothetical wind tunnel with the Navier–Stokes and continuity equations. The equations have been solved numerically, using the Galerkin Finite Element Method. The Reynolds numbers are varied from 0.02 to 2000 for all the structures. The numerical results of pressure coefficients are compared and discussed with data of eurocode’s for wind actions. The pressure coefficients given by the eurocode in the leeward side of the roof are close to the results derived from this numerical estimation, in most cases. However, in the windward side, the results indicated that a further segmentation of the pressure coefficients would be better.
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