CANOPIES
A folded plate structure for a small canopy at the entrance of a building is shown. This folded plate has four segments. A two segment structure is not desirable because it has very little torsional resistance. This instability can be demonstrated by a paper model having the ends of the model glued to vertical pieces of cardboard, acting as stiffening members. If it is absolutely necessary to have a two element system, a torsion member can be placed in the valley which will carry the unbalanced loads.
Stiffeners can often be hidden on the top surface so they are not in evidence and the shell will appear to spring from the vertical column. At the wall of the building there should also be a stiffener hidden in the wall construction. Provision should be made for drainage of the center valley.