Failure conditions for stand-alone cold-frame greenhouse under snow loads

In South Korea, even snowfalls under the design snow loads are frequently known to cause significant deformations or failures of stand-alone cold-frame greenhouses. However, the possible causes of such events are not reflected in the structural design criteria currently used. To estimate the deformations related to structural failures, this study set up possible scenarios to be able to make the structural failures and examined the reasons through scaled-down experiments and nonlinear structural analyses. Hinge boundary conditions of supports and non-uniform snow loads occurred by the repetitive freeze–thaw cycles of the soils surrounding the supports without concrete foundations, and differences between internal and ambient temperatures, respectively, were considered. Two-dimensional scaled-down models of the greenhouses were constructed based on the similarity law. The experimental results were compared with those from nonlinear structural analyses of linear elastic–plastic models. For fixed boundary conditions at both ends and uniform snow loads, the relative errors of displacements between the experimentally obtained values and the results of the finite element analyses were within 6.10%. The results revealed that structural failures occurred in all cases with hinge boundary conditions for the supports at both ends for both uniform and non-uniform snow loads, but the greatest deformation behavior of the structure was observed with a hinge–hinge boundary condition and non-uniform snow loads where the horizontal displacement was similar to the vertical displacement. The temporary installations of diagonal braces in the greenhouses when heavy snowfalls are forecasted are therefore recommended to reduce the side sway.