Fiber-reinforced polymer (FRP) composites have been used more often over the past decade than before in new construction as well as in repair of deteriorated bridges. Many of these bridges are on low-volume roads, where they receive very little attention. It is imperative that new bridge construction or repair be long lasting, nearly maintenance free, and as economical as possible. Relative to those factors, FRP composite bridges have been found to be structurally adequate and feasible because of their reduced maintenance cost and limited environmental impact (i.e., no harmful chemicals leaching into the atmosphere with longer service life). In West Virginia, 23 FRP composite bridges have been constructed, among which 18 are built on low-volume roads that have an average daily traffic (ADT) of less than 1,000, including 7 with ADT less than 400. General FRP composite bridge geometry and preliminary field responses are presented as are some of the preliminary construction specifications and cost data of FRP composite bridges built on low-volume roads in West Virginia
The measurement of applied stress on bridges can provide valuable information on the condition of the structure. The conventional technique for measuring applied stress is with a strain gage. However, strain gages can be time consuming to install because first the surface must usually be prepared. On a bridge, paint removal will most likely be necessary as part of this surface preparation. When dealing with lead-based paints, which are considered hazardous waste, many time consuming removal procedures are required. Because of these factors, a device that measures applied stress without requiring paint removal could be useful. While a "clamp-on" strain gage can also be used to measure applied stress without requiring paint removal, this type of strain gage can not be used on some bridge details, such as webs of 1-beams and tops of box girders. An ultrasonic technique using non-contact electromagnetic transducers provides a possible method for applied stress measurement which is not limited by the same factors as those with conventional strain gages. The transducers operate through nonconductive and conductive (lead-based) paint and work on rusted, pitted surfaces. Our previous research developed a technique for measuring applied stresses on bridges with EMATs and included many laboratory tests. This paper describes field applications of the technique on actual bridge structures, as well as additional system testing and instrument calibration in the laboratory.
Fiber-reinforced polymer (FRP) composite materials have shown great potential as alternative bridge construction materials to conventional materials such as steel and concrete. This is especially valid in the field of repair and rehabilitation of existing bridges as well as in new bridge construction. The acceptance of composites in the highway bridge industry is mainly due to their superior properties such as high strength, durability, corrosion resistance, and fatigue resistance. Moreover, FRPs are well suited for mass production of structural shapes because of their high strength-to-weight ratios, which has resulted in the rapid installation of FRP modular decks on highway bridges. Details related to the construction of FRP modular decks as replacements on existing highway bridge superstructures are provided. In addition, details on shipping, handling, erection, assembly, deck-to-deck connections, deck-to-stringer connections, joints, and wearing surfaces are discussed.
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