Greenhouse structures SLS analysis: experimental results and normative aspects

The main parameters involved in the design of greenhouses in which the cladding system is not tolerant to frame displacements, resulting from the design actions, are displacements and deformations: the Serviceability Limit State (SLS) analysis is usually more restrictive than the Ultimate Limit State. The European steel greenhouse structural standard EN13031-1, provides a section dedicated to criteria for SLS design of this kind of structure. A full scale load test on a duo-pitched roof greenhouse structure has been performed in order to calibrate the SLS criteria of the standard. Horizontal and vertical loads were applied till the collapse of the structure. Stresses and deformations have been measured during test. Results have been compared with those of FEM linear elastic analysis performed on a model of the structure loaded with some loads of the test. The collapse occurred for instability of compressed element of the trellis girder. The results of calculated 2D displacements are higher than 3D, this difference is not very relevant for vertical loads, while applying horizontal loads 2D analysis is not representative of the real behaviour of the structure resulting more conservative than 3D. Experimentally measured displacements values were generally higher than those calculated both with 2D or 3D analysis depending on the assessment of internal connections and on the difficulty of simulating real connections with perfect one. Finally, the main limiting values of deformations and deflections of the tested structure in accordance to EN13031-1 have been calculated.