From the Architect....
A unique barrel shell is the hangar for the Ideal Cement Company, Fig. 5.6. At that time they produced a lightweight aggregate and wished to demonstrate the possibilities for construction of shells. We used a structure, square in plan, with abutments at two corners with a rear wall supporting the shell on two of the sides, and an arch, broken at the middle, to carry the structure above the doors. Also there was a stiffening rib from abutment to abutment. The front arch was not continuous, and created a tensile force on the shell which was carried by prestressing cables across the top. The structure acts essentially as a short barrel shell, and is in compression, the only difference is that there is no beam element at the base. We considered using a hyperbolic paraboloid, but rejected it because of the difficulty of forming, and inability of the structure to take the tensile forces caused by the broken arch.
The hangar fitted the airplane like a glove, and was a handsome structure when the hangar doors were open, but was rather box-like when they were closed. - Milo Ketchum
The Fairchild F-27 owned by the Ideal Cement Company and housed in Hangar 61 - circa 1960 at SFO