Wall Repair with FRP
Glass and carbon FRP offer ideal repair and strengthening solutions for a variety of wall types, including concrete, brick, Unreinforced Masonry (URM), and Parapet Walls. FRP systems can be used for shear and flexural strengthening of walls, seismic and blast protection, repair of damage, replacing deteriorated steel, waterproofing, etc. Another common application of FRP is to strengthen the areas around openings in walls that may have to be created for doors and windows.
Thin sheets of FRP with a thickness of approximately 0.05 inch (1.3 mm) can be applied similar to wallpaper to strengthen the wall. These materials cure within a day and reach a tensile strength three times that of steel. QuakeWrap engineers will determine the number and orientation of fibers in each layer of the FRP fabric and will provide sealed engineering drawings for such repairs.
Strengthening of Shear Walls
The strength of concrete shear walls can also be significantly enhanced by carbon or glass FRP fabrics. Conventional repairs require doweling new reinforcing bars and adding shotcrete to the wall. This adds significant weight to the structure, is time-consuming to implement and reduces the usable floor area of the floor. In the McKinley Tower shown here and the video below, these options were considered and later abandoned.
When the stresses on the wall are relatively low, glass FRP fabrics offer an economical solution. In areas with higher stresses, carbon fabrics could be advantageous for seismic upgrade of shear walls.
The boundary elements around the windows can also be strengthened with FRP fabric and through bolts as shown here.
Attention must be paid to load transfer mechanisms between the walls and the floor to ensure a continuous load path throughout the building.
All these repairs are very thin, keeping the wall thickness virtually unchanged. If desired the strengthened wall can be painted, stuccoed or covered with other architectural finishes.
Features & Benefits:
- Increases shear and flexural strength of walls
- Increases wall thickness by less than ¼ inch (5mm)
- Adds very little weight to the wall
- Strengthens entire wall by treating only a fraction of the surface area
- Serves as a waterproofing system
Projects
- All Hallows Academy, FRP Retrofit of Masonry Wall in School Building, San Diego, CA
- Courtaulds Aerospace, Repair of Tiltup Concrete Wall Panels with Glass FRP, Glendale, CA
- Fox Historic Theater, FRP Retrofit of Historic Building, Tucson, AZ
- Historic Building-Ebensburg, Historic Masonry Building Strengthened With Glass And Carbon FRP, Ebensburg, PA
- Veteran Affairs Medical Center, FRP Retrofit of Masonry Wall in Health Care Facility, Tucson, AZ
- Anchorage International Airport, Seismic Strengthening Columns with Carbon FRP, Anchorage, AK
- McKinley Tower, FRP Retrofit of Shear Walls in High Rise Building, Anchorage, AK
- Mitsubishi Warehouse, Repair of Earthquake Damaged Tiltup Walls with Glass FRP, Compton, CA
- University of Arizona Mirror Lab Thimble, Repair of UA Mirror Lab Thimble with Glass FRP, Tucson, AZ
- United Airlines Maintenance Facilities, Strengthening Unreinforced Concrete Block Walls with GFRP, Oakland, CA
Sample Publications & Case Studies
- Fiber Reinforced Polymers, Seismic Retrofit of the McKinley Tower By Mo Ehsani, Structure Magazine, July 2007, 1-3
- Behavior of Retrofitted URM Walls under Simulated Earthquake Loading, Ehsani, M.R., Saadatmanesh, H., and Velázquez-Dimas, J.I. ASCE Journal of Composites for Construction, 3(3) 134-142., 1999
- Modeling the Out-of-Plane Bending Behavior of Retrofitted URM Walls, J. I. Velázquez Dimas, M. R. Ehsani, J. H. Castorena González, and A. Reyes Salazar 087
- Out-of-Plane Behavior of Brick Masonry Walls Strengthened with Fiber Composites, Velázquez-Dimas, J.I., Ehsani, M.R., and Saadatmanesh, H ACI Structural Journal, 97(3), 377-387, 2000