Florida Department of Transportation Approved Applications
Overview
The deterioration of reinforcing and prestressing steel within concrete is one of the prime causes of failure of concrete structures. In addition to being exposed to weather, concrete transportation structures in Florida are also commonly located in aggressive environments such as marine locations and inland water crossings where the water is acidic. Cracks in concrete create paths for the agents of the aggressive environments to reach the reinforcing and/or prestressing steel and begin the corrosive oxidation process. An innovative approach to combat this major issue is to replace traditional steel bar and strand reinforcement with Fiber Reinforced Polymer (FRP) reinforcing bars and strands. FRP reinforcing bars and strands are made from filaments or fibers held in a polymeric resin matrix binder. FRP reinforcing can be made from various types of fibers such as glass (GFRP), basalt (BFRP) or carbon (CFRP). surface treatment is typically provided that facilitates a bond between the reinforcing and the concrete.
Beneficial characteristics of FRP reinforcing include:
• It is highly resistant to chloride ion and chemical attack• Its tensile strength is greater than that of steel, yet it weighs only one quarter as much• It is transparent to magnetic fields and radar frequencies• GFRP and BFRP have low electrical and thermal conductivity
Traditionally, composite materials like FRP have been used extensively in aerospace and consumer sporting goods applications where the material's high strength to weight ratios were first exploited. In the 1960s US Government agencies recognized the potential benefits that composites can provide to society's infrastructure and thus begin funding significant amounts of research in the field of FRPs. Since then, advances in the field of polymers, advancements in production techniques and implementation of authoritative design guidelines have resulted in a rapid increase in usage of FRP bars and strands, especially in the last 5 years. Because of these advances, the FDOT Structures Design Office has implemented its first specifications and design criteria to support the use of FRP bars and strands in major bridge components.BFRP is an emerging technology in the US, and as such still in a development phase by the Department for Specification and Standards. The use of these innovative material in certain Florida bridge components will keep Florida on the leading edge in the design of state-of-theart transportation facilities.
Usage Restrictions / Parameters
GFRP, BFRP and/or CFRP reinforcing bars may be used in the following concrete components when approved by the SSDE:
• Approach Slabs• Bridge Decks and Bridge Deck overlays• Cast-in-Place Flat Slab Superstructures• Pile Bent Caps• Pier Columns and Caps• Retaining Walls, Noise Walls, Perimeter Walls• Traffic Railings• Pedestrian/Bicycle Railings• Bulkheads and Bulkhead Copings with or without Traffic or Pedestrian/Bicycle Railings• MSE Wall Panels• MSE Wall Copings with or without Traffic or Pedestrian/Bicycle Railings• Drainage Structures
The use of GFRP, BFRP and/or CFRP reinforcing bars in other locations will be considered on a case-by-case basis.