 Interior structure of a covered bridge utilizing a plank-lattice structure | |
| Ancestor | Truss bridge |
|---|---|
| Related | None |
| Descendant | None |
| Carries | Pedestrians, livestock, vehicles |
| Span range | short to medium |
| Material | wood planks and beams or steel angles and beams, appropriate decking material |
| Movable | No |
| Design effort | medium |
| Falsework required | Sometimes |
A lattice truss bridge is a form of truss bridge that uses many small, closely spaced diagonal elements forming a lattice. The design was patented in 1820 by architect Ithiel Town.
Originally a means of erecting a substantial bridge from mere planks employing lower–skilled labor, rather than heavy timbers and more expensive carpenters and equipment, the lattice truss has also been constructed using many relatively light iron or steel members. The individual elements are more easily handled by the construction workers, but the bridge also requires substantial support during construction. A simple lattice truss will transform the applied loads into a thrust, as the bridge will tend to change length under load. This is resisted by pinning the lattice members to the top and bottom chords, which are more substantial than the lattice members, but which may also be fabricated from relatively small elements rather than large beams.