The purline is often designed as a simple beam, and only it′s strength needs to be calculated, if the roof panel can prevent it′s lateral buckling and torsion.
檩条一般采用简支梁,假定屋面板能阻止其侧向失稳和扭转,则只计算其强度。
2
A new and simple proving method on the famous theorem of total torsion, "the total torsion of closed spherical curve is zero", and two generalized theorems for the. theorem are presented in the paper.