Trust Design Bridge-Pratt

This bridge was one of the bridges that we thought as a group that can hold the much weight because of its structures. At first it was really hard to figure out on how to build it but three minds always work better then one so as we figured out the best way to built it we would test it ourselves.

The Pratt truss was first developed in 1844 under patent of Thomas and Caleb Pratt. Since the 1840s through the early twentieth century, the Pratt has diagonals in tension, verticals in compression, except for the hip verticals immediately adjacent to the inclined end posts of the bridge. Pratt trusses were initially built as a combination wood and iron truss, but were soon constructed in iron only. The Pratt type successfully survived the transition to iron constructions well as the second transition to steel usage. The Pratt truss inspired a large number of variations and modified subtypes during the nineteenth and early twentieth centuries

They are a lot of major subtypes of the Pratt design. Like the Double Intersection Pratt Trust. This subtype was patented in 1847 by Squire Whipple and modified in1863 through addition of crossed diagonals by Lehigh Valley Railroad chief Engineer John W. Murphy. Also there’s the Pratt Half-Hip subtype was developed during the latter part of the nineteenth century. This bridge is characterized by inclined end posts that do not extend the length of a full panel; this subtype became popular in the United States from the 1890s into the early twentieth century. Then there’s the Parker truss was developed by C.H.