Failure mechanisms and reinforcement of pipe-framed solar greenhouses under snow loads

Pipe-framed solar greenhouses are susceptible to structural failure under extreme snow loads due to their inherent structural asymmetry. This study investigated the failure mechanisms of a 10 m-span pipe-framed greenhouse and proposed three reinforcement methods (reinforced by one brace, lattice column, and temporary column) to enhance snow resistance. A novel concept of reinforcement efficiency was proposed to optimize retrofitting decisions. Finite element (FE) analysis reveals that structural failure originates from full-section yielding of the north column caused by excessive bending moments. Among reinforcement methods, installing a temporary column 4.5 m from the south roof end (near mid-span) achieves the highest reinforcement efficiency (365.3% and 437.1% under uniform and non-uniform snow loads, respectively), followed by replacing single-tube columns with lattice columns (59.9% and 63.1% under uniform and non-uniform snow loads, respectively). Bracing between the south roof and column enhances stability, whereas bracing connecting the south and north roofs accelerates failure and should be avoided. It is recommended to set up one temporary column only under extreme snow loads. The north column of pipe-framed solar greenhouses should be designed as a lattice column. Additionally, flat elliptical hollow sections exhibit superior flexural rigidity compared to rectangular or hat-shaped sections under equivalent steel consumption. This study can provide references for the snow resistance design of other similar pipe-framed greenhouses.