Concrete arch bridges combine the compression capacity of concrete to arch over a river with the tension capacity of steel to tie the ends of the arch together. This photo is the Wilson River Bridge, the first concrete tied-arch bridge in America, built in 1931 on Oregon’s Pacific coast highway.

The queen-post truss, typically constructed of timber or steel, has an upper chord (red) in compression, a lower chord (brown) in tension, and two vertical queen post members (blue) in compression. Diagonal tension ties (green) across rectangular center panel resist shear load in the mid-span section caused by unsymmetrical loads.

This shows an elevation or side view of the New Orleans Arena roof structure, which is both a concrete tied arch and a queen-post truss with diagonals in the center panel. The queen-post truss shape was chosen for the New Orleans Arena to provide an attractive mansard roof line. The primary innovation was the new use of concrete for the upper chord compression members in combination with structural steel for the lower chord tension, as in a concrete tied arch bridge, to form a queen-post truss.
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