Arches

Closed Spandrel Masonry Arches Sprandrel Retaining Wall Arch

Traditional Arch Bridge Construction Spandrel Retaining Walls

Traditional Arch Bridge Construction Filled with dirt, up to road level

Traditional Arch Bridge Construction Spandrel Walls Arch Filled with dirt, up to road level

Traditional Arch Problem The funicular shape for dead load is a parabola

Traditional Arch Problem The funicular shape for dead load is a parabola When a point load is applied (say, a horse), it is no longer funicular. Bending moment is present. Masonry cannot take tension. It might collapse.

Traditional Arch Solution Use A LOT OF DIRT

Traditional Arch Solution Use A LOT OF DIRT Huge dead loads pre-compress the masonry so much that the tension from the bending action of a Horse Load will never overcome the compression

Traditional Arch Solution Use A LOT OF DIRT Huge dead loads pre-compress the masonry so much that the tension from the bending action of a Horse Load will never overcome the compression Irony: more dead load strengthens a traditional masonry arch.

Puzzle This arch is indeterminate, yet you can solve it. Why?

Puzzle This arch is indeterminate, yet you can solve it. Why? It is funicular. M=0, everywhere. So…

You can place pins wherever you want them, to facilitate analysis. Puzzle This arch is indeterminate, yet you can solve it. Why? It is funicular. M=0, everywhere. So… You can place pins wherever you want them, to facilitate analysis.

You can place pins wherever you want them, to facilitate analysis. Puzzle This arch is indeterminate, yet you can solve it. Why? It is funicular. M=0, everywhere. So… You can place pins wherever you want them, to facilitate analysis.