Reinforcement for Pipe-Framed Greenhouse under Snow Load and Design Optimization Considering Steel Mass

To investigate the low-cost reasonable design of a pipe-framed greenhouse (pipe house) under snow load, seven numerical finite element models of simple pipe houses were analyzed by stress analysis and buckling analysis. These determined the optimum position of bracing for pipe houses. The influence of the width and ridge height of the structure and the section modulus of the arch pipes on the upper limit of the allowable snow load was also obtained. Moreover, the relationship between a reasonable pipe house design and the arch pipe used for the structure was investigated. For the structures modified by the addition of two tension braces at points between 63% to 70% of the ridge height, the allowable snow load was significantly increased. The influence of addition of braces was remarkable for wider spans. There was little influence from the difference of the ridge height of the pipe house on the maximum allowable snow load for the heights considered using stress analysis. However, the maximum allowable snow load obtained by the buckling analysis decreased 54% as the ridge height increased so a buckling analysis is important. Considering the change of the support condition due to softening of the ground, increasing the size of the pipe section increases the allowable pipe spacing and reduces the total steel mass and shading of the structure. For a typical size pipe house, by replacing arch pipes of 19.1 mm diameter with 1.1 mm thickness by pipes of 42.7 mm diameter with 2.0 mm thickness, steel mass and shading rate decreased by 58% and 77% respectively.