Concrete takes flight: From for the birds

The key to the whole was the gerberette [beam]. After all, a column is a column: a hollow round pole to carry the load. And a tie is easily found; it became a solid round bar. No, the gerberette was the thing. … [W]hat shape should it take? The forces and loads in the piece - I like the word piece, it makes me feel like an artist when I use it - were the principal determinants of its shape: slender at the tension tie end where the load is applied, deep and strong over the column where the load and moment reach a maximum, and slender again at the point of pick up of the [trussed] beam. The development of form and the interactive nature of the design were complex.