In time some places like Pennsylvania continued building truss bridges for long spans well into s, while other like Michigan started building standard plan concrete girder and beam bridges. From the first truss bridge, engineers experimented with different forms of truss bridges trying to find better shape and the one that will suit them for the particular problems.
Because of that we have today many forms of truss bridges. Truss bridge can have deck roadbed on top deck truss , in the middle through truss , or at the bottom of the truss. If the sides of the truss extend above the roadbed but are not connected, it is called a pony truss or half-through truss.
Mahan Construction. A joint venture comprised of URS and Stantec designed the superstructure, which was constructed by a joint venture of Haydon Bridge Co. Mahan Construction also worked with Haydon and Kay and Kay as a subcontractor and performed the steel erection for the truss. The project was broken into an initial substructure contract and a superstructure contract that followed later, to help spread out the cost.
While the substructures were under construction, the administration in charge at that time wanted to change the appearance of the truss, reduce the truss depth and eliminate some of the truss bracing to give a more open appearance to the bridge from what was originally proposed.
The design team faced challenges arising from the demands of a long main span on a relatively shallow truss. These challenges were compounded by rigorous seismic loading on piers designed to accommodate a different structure. The design team overcame the challenge by finding a solution that did not require retrofitting the existing foundations or piers. This continuous-truss bridge carries U. Route 27 across the Ohio River, linking Newport, Ky.
It is believed to be the longest continuous-tied arch bridge in the world. The Bethlehem Steel Co. Robers Construction Co. It was built using the balanced-cantilever construction method, with the trusses constructed outward from each pier and only a single steel bent next to the pier to provide temporary support. Because it was built during wartime, the project experienced several delays of materials and labor.
The bridge was extensively renovated in the early s, getting a new deck and a pedestrian walkway. Truss bridges have a long pedigree. The first ones were made of wood and erected in various European countries at least as early as the 16th century. Beginning in the late s, many of them were built throughout the United States. Beginning in the late s, all-metal truss bridges became widespread, particularly within the railroad industry. Trusses are assemblies of beams or other supports, typically arranged in combinations of triangles.
Truss bridges take many forms. One early truss-bridge design, the bowstring-arch truss, was patented in by Squire Whipple, a Massachusetts engineer who is considered the father of iron bridge building in the U.
Its two longest spans each measured meters. At 3, m overall, it was, at the time, the longest metallic structure in the world. Truss bridges were a popular choice of bridge designers in the U. One variety of truss bridge played an important role in World War II.
A civil engineer working in the British War Office, Donald Bailey, designed a portable, prefabricated truss bridge in If the diagonal members are made from the solid material such as metal bars , the heavy load of the bridge may cause the need for implementing reinforcements to the center area of the Pratt truss bridge, since that part of the bridge will experience the strongest force loads.
Those center areas can be reinforced with stronger materials, or be subdivided into K or Y-shaped patterns. Pratt truss bridges are statically determinate all of its support reactions and member forces can be calculated using only the equations of static equilibrium , which made them capable for use in scenarios where bridge designers needed to span great distances. Some of the most famous bridges that feature Pratt Truss design are:.
Pratt Truss Bridge Since its introduction in , this bridge design became part of hundreds of bridges created up to Second World War.
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