Composite Repair Technology
Fiber reinforced polymer (FRP) composites are thin laminates that are externally bonded to the structural members using epoxy resin. The FRP dramatically increases the members’ load carrying capacity.
These structural strengthening systems are made of high strength fibers such as glass, Kevlar, and carbon embedded in resin. The resin protects the fibers, maintains their alignment, and distributes the loads evenly among them.
FRP’s, which have been widely used in industries such as aerospace, automotive, and sport equipment, are now becoming used extensively for the structural upgrade of steel and concrete structures. In addition to their high –strength and light weight properties, important characteristics of FRP’s for structural repair and strengthening applications are their non-corrosive properties, timeliness and ease of installation, low cost relative to demo and reconstruction. FRP materials can be adhered to beams and slabs to increase their shear and flexural capacity, and can be wrapped around columns to increase their load carrying capacity and ductility during seismic events.
FRP systems may also comprise of pre-manufactured strips and plates that are bonded to structural slabs, steel, deck, etc. using epoxy resin. Pre-cured FRP elements are more suited for flexural upgrade of columns, beams, and slabs. As with any other externally bonded system, the bond between the FRP system and the existing concrete is critical to achieve a composite behavior with the existing member. Accordingly, the most current National Association of Corrosion Engineers, and Society of Protective Coating Standards are used for proper surface preparation for ensuring a successful FRP structural upgrade.
Some advantages of FRP Composite Systems include but no limited to the following:
- High tensile strength
- Minimum disruption to operating facility
- Low weight
- High strength to weight ratio
- Excellent fatigue behavior
- Low downtime
- Low cost
- Ability to contour existing structures
- Minimum change to dimensions and weight of strengthened elements
- Engineered design
- Internal repair to below grade PCCP pipe avoiding costly excavation
- External repairs, even with active leaking can be performed on any size pipe
- Process tanks can be easily repair after suffering structural damage due to corrosion
- Seismic retrofitting of steel, concrete, and masonry structures
- Concrete columns and beams where rebar loss has eroded structural value
- Increasing load capabilities without adding substantial weight or obstruction and without welding or hot work
- Protection of structural integrity and control systems in severe blast conditions
- Blast and ballistic upgrade of structures to shield structure, strengthen existing structural elements, provide alternate load paths to prevent progressive collapse, and offer debris control.