Contact:
Terri Albert
(800) 552-4WRI [4974]
Outside US, 1-860-808-3000 x356
wirereinforcementinstitute.org

FINDLAY, OHIO, June 12, 2001 -- In the world of construction, no project can quite match the sex appeal of the building of a new sports stadium. Sure, highways are more useful and office buildings can be more architecturally intriguing, but there is something about sports stadiums that captures the imagination of the public. Maybe it's the thrill of the dreams of the games that will take place inside or the thoughts of tailgating in the parking lot. Whatever the reason, stadium construction is booming in America and this means lots of work for those involved in their construction.

Stadium design has changed a lot over the past century. One just has to compare an old style stadium, like Fenway Park in Boston, to a new stadium like Ravens Stadium in Baltimore to see. One of the biggest drawbacks with old stadium design is the need for support columns for the upper decks. This leads to obstructed views for those unfortunate enough to sit behind one of them. Just ask a poor fan at Fenway with a column blocking his or her view of 2nd base.

Early in the development of large stadiums, engineers had to devise a way to create platforms that provided enough support for spectators on the upper levels, but had enough internal support to prevent collapse (and let's not forget about the infamous 1989 earthquake in San Francisco during the World Series). That answer came in the form of prestressing strands and structural welded wire reinforcement (WWR).

"One of the big challenges with the precast/prestressed concrete elements that typically support the stadium seating, is that the slabs are very thin, which doesn't allow much clearance for embedding the reinforcing", says David Orndorff, engineering manager with the Shockey Precast Group in Winchester and Fredericksburg, Virginia. His company has been involved with a number of stadium projects over the past few years including the new The Pittsburgh Pirates' PNC Park, the Baltimore Ravens NFL Stadium, Core States Arena home of the NHL Philadelphia Flyers, MCI Arena in Washington D.C. (the NBA Wizards and NHL Capitals), Camden Yards in Baltimore and a number of university stadiums including the University of Virginia, University of Maryland and Virginia Tech.

Shockey Precast supplies structural precast members and architectural precast members as well. Additionally, the company works with architects to help design the engineering specs for projects. "As designers, manufacturers and erectors, it's usually our job to take the basic architectural and structural scheme for a stadium and engineer efficient, constructable details for the job," says Orndorff. "It's during this process that we have to figure out how to ensure the structural integrity of the elements and one of those ways is through the use of welded wire reinforcement."

While the technology celebrates its 100th anniversary this year, many engineers and architects are unaware of the advantages of welded wire reinforcement. Unlike reinforcingbars, WWR comes to the jobsite pre-welded in a sheet, which saves the traditional time of tying rebars together. Additionally, the sheets can be custom ordered so that they can be bent or designed in such a manner as to facilitate easier reinforcement of complex shapes. Precasters like Shockey are big users of WWR because it allows for quicker production of precast components.

For its stadium projects, Shockey uses WWR primarily for the precast risers (bleachers) in the stadium. These are the concrete slabs on which the seats are eventually mounted. These slabs are usually very slender and come in asymmetrical shapes and have to support their own weight as well as those of the seats and spectators.

"No question about it, these risers are the biggest application of WWR that we see in precast stadium construction," says Orndorff. "Utilized in conjunction with 270 ksi prestressing strand, WWR nearly eliminates cages of bent rebar in the slender precast members. To use rebar in place of WWR would result in difficult clearances and tolerances, while costs would become prohibitive. Additionally, the dimensional stability of a WWR cage is much better than you would get with a rebar cage. Using WWR is a no muss, no fuss proposition. We've been using it for almost 20 years and I can't imagine doing it any other way. For stadium seating construction, we use a wire cage that is made of W4 wire spaced at 4" on centers in the direction that we need the reinforcement."

In the architectural precast units, Shockey Brothers also uses WWR. These are the accents that are placed on the outside of the stadium and that enhance the look of the facade. In these pieces, WWR is a predominant reinforcer. Orndorff says from a structural standpoint, WWR and rebar offer similar reinforcement properties for this applicaiton, but WWR is less expensive and quicker to use.

"Over the past ten years, the precast industry has become more advanced," says Orndorff. "We've been able to get wire cages with more creative bends and shapes. The biggest innovation for us has not been the increase in the diameter of the wire or the variation of spacings, but in the availability of custom-bent shapes. Some of the products need some pretty elaborate bending configurations, but we typically don't care to bend them ourselves. However, the manufacturers we use are able to custom bend the products, which works out great."

Shockey also uses WWR in many of its other precast projects. The company actually derives much of its workload from a less publicized form of construction: parking garages. In those types of structures, WWR is heavily used for reinforcement in the the precast slabs used as driving and parking surfaces. Just like the bleacher setups in the stadiums, the slabs are thin but need lots of internal support. Shockey also uses WWR for large industrial wall panels in other building projects.

"It's intriguing that many architects and engineers aren't entirely familiar with welded wire reinforcement," says Orndorff. "Most are trained in terms of rebar but when we talk about using WWR in our stadium projects, we've never had difficulty convincing them of its benefits. The ACI Code and guides consider WWR equal to rebar. When you're talking in terms of large projects like stadiums, time is usually a big issue and the quicker we can fabricate and erect the precast, the more money we save the owner. The fact that WWR allows us to do things that other forms of reinforcement don't, is just icing on the cake."

For more information about welded wire reinforcement, contact the Wire Reinforcement Institute, the concrete construction industry's leading source for timely, objective and credible information on the uses and benefits of WWR. WRI works closely with government agencies, allied industries and organizations to ensure the most accurate, up-to-date codes, standards, specifications and regulatory requirements. WRI works to promote the superior performance attributes of WWR products across the full range of reinforcement applications. WRI's number is (800) 552-4WRI [4974], or visit our website at www.wirereinforcementinstitute.org.