Collapse full scale test on a steel greenhouse tunnel structure

A full scale test was carried out on an arch greenhouse. loaded with a combination of vertical and horizontal forces. The increasing of the loads allowed the analysis of the different states of the structure before the collapse: elastic, elasto-plastic, plastic. Strain gages applied on the structure and a data logger system were used to measure the stress condition in different structural sections. The results of the tests were compared with calculations carried out by a finite element model (FEM) adopting first order elastic analysis and second order one, introducing the effect of the displacements of the structure in the equilibrium equations. The comparison allowed to understand the structural behaviour and the changing of the constraints with the increasing of loads, and the differences between the theoretical model usually adopted in calculation and a real structure. After the definition of the structural model the results highlighted differences of about the 14% between the calculated and measured stresses relating to horizontal and vertical forces. Moreover, the second order analysis, for several load conditions, was less adherent to the reality than the linear elastic one, showing that not always the complexity of calculation is linked to the reliability of results.