FHWA > Bridge > PBES > Publications > Prefabricated Bridge Elements and Systems in Japan and Europe |
Prefabricated Bridge Elements and Systems in Japan and Europe
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Partial Depth Concrete Decks Prefabricated on Steel or Concrete Beams:One system in Germany involved the casting of partial depth concrete decks on steel or concrete beams prior to erection of the beams. After the beams are erected, the edges of each deck unit abut the adjacent member and there is no need to place additional formwork for the cast-in-place concrete. This process speeds construction and reduces the potential danger of equipment falling onto the roadway below since a safe working surface is available immediately after beam erection. |
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Poutre Dalle System:Another method to eliminate formwork and provide a working surface is provided by a system known as the Poutre Dalle system. In this system, inverted T-beams are placed adjacent to each other and then made composite with cast-in-place concrete placed between the webs of the tees and over the tops of the stems to form a solid member. |
Four innovative ideas for bridge deck systems were identified and are recommended for implementation in the United States.
Full Depth Prefabricated Concrete Decks:The use of full depth prefabricated concrete decks reduces construction time by eliminating the need to erect formwork and provide cast-in-place concrete. The deck panels are connected to steel beams through the use of studs located in pockets in the concrete deck slab. The use of full depth prefabricated concrete decks provides a means to accelerate bridge construction using a factory produced product. |
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Hybrid Steel-Concrete Deck Systems:The Japanese have developed hybrid steel-concrete slab systems for bridge decks. This steel component of the system consists of transverse beams that span between the longitudinal girders and cantilever beyond the edge girders. The bottom flanges of the transverse beams support steel formwork for the bottom of the slab while the top flanges support the longitudinal deck reinforcement. When filled with cast-in-place concrete, the system acts as a composite deck system. The system allows rapid placement of a lightweight deck formwork system complete with reinforcement without the use of heavy lifting equipment. |
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Deck Joint Closure Details:Prefabricated deck systems require that longitudinal and transverse joints be provided to make the deck continuous for live load distribution. This is accomplished by using special loop bar reinforcement details in the joints. Various joint details observed during the tour should be developed for use in the United States to facilitate the use of prefabricated full depth deck systems. |
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Multiple Level Corrosion Protection Systems:In Japan, Germany, and France, concrete bridge decks are covered with a multiple level corrosion protection system to prevent the ingress of water and deicing chemicals. The systems generally involve providing adequate concrete cover to the reinforcement, a concrete sealer, waterproof membrane, and two layers of asphalt. This type of corrosion protection system may be beneficial with prefabricated systems as a means of protecting the joint regions from potential corrosion damage, thereby ensuring a longer service life. |
One substructure system is recommended for implementation in the United States.
The SPER System:The SPER system is a method of rapid construction of piers using precast concrete panels as both structural elements and formwork for cast-in-place concrete. Tall hollow piers use panels for inner and outer formwork, while shorter solid piers use panels for the outer formwork only. Testing has shown that the system provides similar seismic resistance as a conventional cast-in-place system. The system has the advantage of more rapid construction with improved constructibility and quality. |
During the tour, many different methods that can be used to remove partial or complete existing bridges and move bridge components or complete bridges into place were observed. These methods allow a new bridge to be built at one location near or adjacent to the existing structure and then moved to its final location in a short period of time. Construction can, therefore, take place in an environment where construction operations are completely separated from the traveling public. These methods reduce traffic disruption times from months to hours or days, restore the use of existing highways in significantly less time, improve work zone safety, minimize environmental impact, and improve constructibility. This concept of building bridges off line and then moving them into place needs to be developed for use in the United States. Various systems for moving bridges and their components were identified during the tour.
Self Propelled Modular Trailers:In Europe, it was observed that large bridge components or even complete bridges weighing several thousand metric tons have been built at one location and then lifted and transported to their final location using a series of vehicles known as self propelled modular trailers (SPMTs). These multi-axle computer-controlled vehicles have the capability of moving in any horizontal direction while maintaining their payload geometry undeformed or distorted, horizontally, and keeping equal axle loads. |
In addition to using conventional land and/or barge mounted cranes to erect large structures, special load frames have been developed to erect prefabricated components. One example is the modular jacking system used to erect prefabricated pylons on the Millau cable stayed bridge in France. The other methods of moving bridge components included the following:
These systems can be used to minimize the time that an existing bridge is out of service while it is replaced, many within 3 to 48 hours.
The scanning team has already scheduled 17 presentations at national technical meetings sponsored by FHWA, AASHTO, and other organizations to disseminate information from the scanning tour. In addition, the team has formed a group to prepare Scanning Technology Implementation Plans for the technologies described above. Initial drafts of these plans will be reviewed during a meeting of the team in June 2004 prior to completion of the first draft of the scanning report.
Vasant Mistry
Office of Bridge Technology
202-366-4599
E-mail Vasant