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The Pratt truss design remained popular as bridge designers switched from wood to iron, and from iron to steel. [20] This continued popularity of the Pratt truss is probably due to the fact that the configuration of the members means that longer diagonal members are only in tension for gravity load effects.
The Pennsylvania (Petit) truss is a variation on the Pratt truss. [26] The Pratt truss includes braced diagonal members in all panels; the Pennsylvania truss adds to this design half-length struts or ties in the top, bottom, or both parts of the panels. It is named after the Pennsylvania Railroad, which pioneered this design.
The only maintenance a Howe truss requires is adjustment of the nuts on the vertical posts to equalize strain. [1] The diagonals in a wooden Pratt truss proved difficult to keep in proper adjustment, so the Howe truss became the preferred design for a wooden bridge [1] or for a "transitional" bridge of wood with iron verticals. [2]
Only a few single-lane Pratt truss bridges remain in California today. The Hansen Bridge is closely tied to the community planning and development of Downieville in Sierra County, particularly in its role following the 1937 Downieville flood. It serves as a notable example of the truss bridge design. Its period of significance spans from 1935 ...
Pratt truss bridges in the United States (281 P) B. Baltimore truss bridges (1 C, 14 P) Pages in category "Pratt truss bridges" The following 22 pages are in this ...
They do not have any sort of pre-defined configuration in the way that a Pratt truss does. Rather, bents are simply cross-sectional templates of structural members, i.e., rafters, joists, posts, pilings, etc., that repeat on parallel planes along the length of the structure. The term bent is not restricted to any particular material.
Old Appleton Bridge is a historic Pratt Truss Iron Bridge located at Old Appleton, Cape Girardeau County and Perry County, Missouri. It was built in 1879, and consists of a wrought iron, pin-connected, Pratt through truss main span, with two pin-connected, three panel Pratt pony-truss approach spans. It rests on limestone block masonry piers ...
These bridges include a stone arch bridge constructed in 1843, a wrought iron Pratt truss bridge (1878) and a twisted wire cable suspension footbridge built in 1888. These three bridges represent the evolution of 19th-century bridge design, and together were designated a National Historic Civil Engineering Landmark by the American Society of ...