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The Pratt truss form, invented in 1844 by Thomas and Caleb Pratt, is the most common truss form in California and the United States. This form first appeared as a "combination truss" built in wood and iron with wooden vertical members, chords, and endposts, and iron tension diagonals. The basic form changed to all-metal construction by the 1880s.
Plank framed truss was the name for roof trusses made with planks rather than timber roof trusses. In the 20th century, it was typical for carpenters to make their own trusses by nailing planks together with wood plates at the joints. Today similar trusses are manufactured to engineering standards and use truss connector plates.
A Howe truss is a truss bridge consisting of chords, verticals, and diagonals whose vertical members are in tension and whose diagonal members are in compression. The Howe truss was invented by William Howe in 1840, and was widely used as a bridge in the mid to late 1800s.
For the longer spans, it is uncertain if the Greeks or Romans invented the truss but the Romans certainly used timber roof trusses. Before 650 BC the now famous ancient Greek temples were built of wood, but after this date began to be built of stone. [ 22 ]
The sheaves at the top of each tower were lifted in place during high tides in order to reach the necessary height. [2] The 1960 superstructure replacing the 1919 bascule bridge includes the four truss spans west of the main lift span and one truss span east of the main lift.
The earliest wooden truss connections consisted of mortise-and-tenon joints and were most likely crafted at the construction site with the posts. Since most early trusses were made from unseasoned posts, the subsequent shrinkage would create cracking at the mortise-and-tenon joints. Additionally, the mortise-and-tenon joints in older trusses ...
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One of the most popular designs was the Burr Truss, patented in 1817, which used an arch to bear the load, while the trusses kept the bridge rigid. Other designs included the King, Queen, Lattice, and Howe trusses. Early trusses were designed with only a rough understanding of the engineering dynamics at work. [9]