New Opportunities For a Time-Tested Material

The continuing evolution of steel construction means that engineers, architects and contractors have more choices than ever. There’s a steel style for every challenge, whether it’s commercial or residential, superstructure or infrastructure.

Sustainability

Steel construction is sustainable construction. A typical steel structural beam today contains 95% recycled material, and is the most recycled material by weight in the world. What’s more, steel members often can be taken from old structures and reused on new projects. “The recyclability of steel products is a key component in the concept of sustainable construction,” says Del Boring, vice president of construction for the American Iron and Steel Institute (AISI).

AISI and other industry organizations are working with the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) program to ensure that architects get the best information on steel’s sustainable benefits. The Cool Metal Roofing Coalition (www.coolmetalroofing.org) and the Steel Recycling Institute (www.recycle-steel.org) also offer resources online for those interested in building green with steel.

Non-traditional applications
Steel is gaining ground in some non-traditional markets. Newer systems that provide extended rust protection—and designs that take advantage of thinner and fewer columns—make steel more attractive for parking structures. Development of steel systems that can match the floor-to-floor heights traditionally offered by concrete means more choices for multi-story residential buildings.

Once used mainly for one- and two-story structures, light-gauge steel is seeing increased use in load-bearing elements for structures as tall as seven and eight stories, according to Larry Williams, president of the Steel Framing Alliance. With a 38% market share and a ready workforce in place, steel framing for commercial construction is poised for continued growth, adds Williams.

Value of certification
“As international building codes become more complex, those of us involved in the engineering, design and manufacture of building products are challenged to maintain a high degree of engineering knowledge,” says Charles Praeger, executive manager of the Metal Building Manufacturers Association (MBMA). The association recently joined forces with AISC to develop a certification program to help manufacturers stay on the cutting edge, an effort recently recognized by the American Institute of Architects in that organization’s master specification.

High-performance outcomes
During the last decade, steel’s strength has increased by about 30% in typical applications, and high-performance steel is used more than ever. While higher-strength steel enjoys limited use in larger buildings and some seismic applications, HPS 70W and HPS 100W are creating signature bridges that are lighter, stronger and more cost-efficient. Developments in corrosion resistance and toughness mean HPS bridges will last longer than ever before.

“It’s an exciting time to be in this industry,” says Williams. “The sky’s the limit.”

When the Missouri Dept. of Transportation embarked on a plan to rehabilitate approximately 6.5 miles of Route 350 in Kansas City, the team chose rolled steel beams from Nucor-Yamato Steel Co. for replacement of twin bridges over 63rd Street.

“We chose steel beams because we could use smaller girders,” says Dan M. Smith, P.E., structural projects manager for MoDOT. Achieving maximum vertical clearance for the lowest cost was a priority for the design team. “If we had used concrete girders, we would have had to raise the grade on Route 350, and that would raise the overall cost of the project,” says Smith.

Carrying an average of 17,500 vehicles per day, the section of Route 350 addressed in the project is a vital transportation link within the Kansas City area. APAC-Kansas Inc. was awarded a subcontract by the Superior-Bowen Asphalt Co. for the demolition and replacement of the two bridges.

The replacement structures consist of twin 264-ft 4-span rolled beam bridges. The project used a total of 469,920 lb of structural steel.

High traffic levels and the route’s importance to the area forced a tight schedule of four months from demolition to completion, according to Scott Gammon, P.E., area manager of structures for APAC-Kansas. At any given time, his firm has multiple rolled-beam bridges under construction and the crews are accustomed to working fast. Even so, the four-month turnaround was a challenge.

“Rolled-beams have a shorter procurement time, so the fact that it was a rolled-beam structure assisted us in meeting the tight schedule.” For more information, visit www.nucoryamato.com.

Rock Springs Baptist Church in Easley, SC, serves as a place of worship for a congregation of thousands. The centerpiece of the facility is a fan-shaped sanctuary that seats 3,200, offering clear views of the pulpit from any seat. A steel joist roof system from Nucor Vulcraft Group—and some conscientious teamwork—made it possible.

Colin Bailey, P.E., president of Bailey and Son Engineering (the engineer of record on the project), says the biggest challenge was designing a structure that provided clear spans. “We had to arrange the structure so that when the pastor enters the baptistry to baptize someone, he doesn’t have to avoid a column,” jokes Bailey. “That would be very inconvenient.”

The final design consisted of open-web steel bar joists supported at the roof peak by a shop-fabricated structural steel truss. Thirty-seven joists span from the perimeter walls around the sanctuary toward the center of the roof above the pulpit. As the joists approach the hub of the half circle and the space between the adjacent joists gets close enough, every other joist is replaced by a Vulcraft-designed header, reducing the overall span and eliminating bolted field splices. The end result provides the necessary support while working with the constraints of the fan-shaped sanctuary.

“To accomplish the clear span distances and support the suspended catwalk system, there was virtually no more appropriate component than the steel bar joist,” says Bailey.

“Coming up with solutions for client challenges is a big role for our company,” says Brad Stone, design engineer with the South Carolina Vulcraft plant. Stone worked with Bailey early on to streamline the design, including an elaborate system of catwalks for lighting and sound system equipment suspended from the joists. Bailey says cooperation improved the outcome: “We were able to value-engineer the roof system by being able to work with Vulcraft directly.” For more information, visit www.vulcraft.com.

Work is scheduled for completion in January 2005 on Tampa Bay Water’s Regional Reservoir, an off-stream, 15-billion-gallon facility being built on a 1,100-acre site. The enormous reservoir will store excess surface water taken from the Tampa Bypass Canal and the Alafia and Hillsborough rivers when flows are high. The $92-million reservoir is the latest in a series of environment-sensitive water conservation measures begun by Tampa Bay Water, Florida’s largest water wholesaler.

More than 15 miles of American spiral-welded steel pipe—more than half of it in 84-in. diameter—has been installed for the reservoir’s main feed line, the transmission main running from the reservoir and an important connection within Tampa Bay Water’s system—the South-Central Hillsborough Intertie2. A section under the reservoir’s levee required a specially designed 84-in. pipe due to 80 to 100 ft of cover. Requirements included 1-in. wall thickness, installation on cradles and encapsulation in concrete. For more information, visit www.acipco.com.