Pre-Bent Welded Wire Reinforcement Mats Can Save on Installed Costs
Jan. 2, 2020 - Fairfax, VA
The ability to deliver pre-bent, fabricated welded wire reinforcement (WWR) mats to a job site magnifies the potential for significant savings on the installed cost of a project’s steel reinforcement package.
Bending welded wire reinforcement literally adds a third dimension to concrete reinforcement, coinciding with the spatial requirements of reinforcement assemblies detailed on the structural engineer’s design documents. Equally important, the contractor responsible for placing the reinforcement realizes the benefit of the reduction in number of work pieces needing to be handled, positioned, and aligned prior to the concrete pour.
Achievable fabricated geometries include L-style mats, U-style mats, and Z-style mats comprised of the full spectrum of variable bend angles.
Mats can also be fabricated with common 135-degree and 180-degree hooked end terminations to suit anchorage and confinement requirements, with code-prescribed bend diameters duly satisfied by way of interchangeable bender mandrel sizes.
Recent multistory concrete frame construction projects have shown significant savings when using welded wire stirrup reinforcement in mild-reinforced and post-tensioned beams and girders. The use of the "U"-shaped stirrups eliminates several bends and allows for stirrup cages to be dropped into the form with minimal manual adjustment.
Some other examples include:
- WWR precasting of utility vaults, box culverts and other underground precast products
- WWR used in prestressed box beams,single and double-tee beams, and AASHTO girders.
- WWR shaped to the contours of 3- tiered risers for a large stadium --WWR’s rigidity assuring correct positioning in the riser forms and correct concrete cover
Manufacturers of welded wire reinforcement are not only well equipped to provide reinforcement packages that include pre-bent fabricated WWR mats, it is also standard procedure for producers to furnish the corresponding shop and placement drawings necessary to eliminate designer and contractor guesswork during the submittal review and approval stages of construction administration.
There are several overall advantages to using WWR. It reduces material requirements, is easier to inspect, and provides higher strength compared to conventional Grade 60 designs.
Welded wire reinforcement has crisscrossed the world in highways, train stations, subways and major airport runways. It was placed in such famous structures as the Anaheim Stadium, Grand Central Station, the Standard Oil Building, Golden Gate Bridge, Empire State Building, the Nabisco Bakery, the World Trade Center Towers, the Empire State Building, Sears Tower-Chicago, the Abu Dhabi Airport and the Volkswagen plant in Pennsylvania..
According to American Concrete Institute, Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318 R-19), WWR is interchangeable with rebar when used as mild reinforcement. The actual design routines and calculations are identical, with concepts including strain compatibility, tension- and compression-controlled limits, application of reduction (phi) factors, and prescriptive spacing limits related to design all remaining familiar to the design professional.
About the Wire Reinforcement Institute (WRI)
WRI is the world’s leading association of manufacturers, allied industries and professionals engaged in the production and application of structural welded wire reinforcement (WWR) and related concrete reinforcement products. The Institute advances the concrete industry by providing technical, outreach and promotional programs and materials on the applications and benefits of structural WWR. WRI works closely with design firms, universities, owners, contractors and government agencies, to ensure adherence to the most accurate, up-to-date codes, standards, specifications and regulatory requirements. For more information on WRI or WWR, visit www.wirereinforcmentinstitute.org or call 1-860-240-9545.