New Millennium Building Systems' FreeSpan™ cellular (castellated) beams are a featured structural and design element of the new University of Wisconsin Oshkosh Foundation Alumni Welcome and Conference Center that is scheduled for completion by spring 2014. The 40,000-square-foot facility represents a trend: architecturally open, university-hotel-convention center partnerships.
The center will serve as the new front door to the university while providing a new conference and visitor's center for the campus. In addition to housing UW Oshkosh Alumni Relations, Foundation and Business Success Center offices in its location along Oshkosh's Fox River, the center will feature a ballroom with a dining capacity for 430 people, a reservable boardroom for up to 40 people and breakout workrooms. It will be paired with a hotel less than two blocks away from the university.
FreeSpan™ castellated and cellular beams are fabricated differently from conventional steel beams, so as to create wide, open spaces. A hot rolled beam is cut lengthwise using computer controlled plasma arc torches, often in a half-circle or half-hexagonal pattern. The split halves are then offset and welded back together to form a deeper beam with full circular or hexagonal-shaped web openings. The beams have a lighter top half and a heavier lower half. The beam is about 50 percent deeper and up to 40 percent stronger than the original hot rolled section and no added steel is needed.
Ideal for wide-span wide-open bay designs, FreeSpan™ beams offer multiple benefits. They have a greater strength-to-weight ratio than conventional beams and their strength can be precisely matched to loads. Greater lengths (up to 90 feet) and depths (up to 66 inches) compared with conventional beams are possible. Longer span beams install quickly and easily, largely due to their lighter weight. This lighter weight translates to reduced column and footing sizes. The web openings allow mechanical, electrical, and plumbing elements to pass through. They are easily fireproofed on the jobsite, too.
A central design feature of the new two-story center is an 80x125 banquet/meeting area inside the main entrance. This area requires clear spans, so New Millennium fabricated 80-foot FreeSpan™ cellular beams for this area. These beams serve as primary structural members, supporting secondary transverse beams. Operable partitions hang from the beams, allowing the creation of multiple flexible meeting/event spaces.
New Millennium faced a major steel sourcing challenge in supplying the FreeSpan™ cellular beams for the project. The project broke ground in December 2012 and the contract called for the beams to be delivered to the site in early April 2013. But the supplier of the wide flange steel beams, the source beams to be used by New Millennium to fabricate the FreeSpan™ beams, did not have a rolling schedule that would allow New Millennium to meet the project delivery schedule.
New Millennium determined that another steel supplier, Steel Dynamics, could provide the source beams in time for production of the FreeSpan™ beams. According to Betty M. Corkwell, P.E., design engineer–castellated beams for New Millennium, the design specifications called for 48-inch-deep beams and New Millennium made special cuts to 54-inch-deep wide flange beams from Steel Dynamics, which also had a heavier weight per foot, to maintain the 48-inch depth.
The FreeSpan™ beams were shipped according to the delivery schedule, starting the first week in April. Given the beam lengths and the wide flange beam weight per foot, the cellular beams pushed the maximum load limits of the delivery trailers and escorts were used.
We had to use stretch trailers, which means we could stretch them out to a different length depending on what was being shipped, Corkwell said.
The rear axles get more weight than the front axles, so you have to be careful to make sure you stretch the trailer to the maximum limit for something 80 feet long and weighing 256 pounds a foot to make sure the rear axles aren’t being overloaded.
The Flex-Joist™ Gravity Overload Safety System™ provides an enhanced safety provision for floors and roofs that are susceptible to static gravity overloading. The “bend before it breaks” engineering concept allows the steel joist to flex prior to collapse. As the joist steel deflects, it shares the load among adjacent joists, allowing for prolonged, critical time delay for emergency response and evacuation, if necessary.
Building owners and managers have the option of adding electronic alarm monitoring to a Flex-Joist™ installation, with monitoring options both remote and onsite. These options include the use of strain gauge monitors affixed to critical joist components to provide accurate feedback, as well as optical (laser) infrared sensors for cost-efficient deflection monitoring of open joist bays—or a combination of strain and deflection monitoring.
New Millennium can partner with experienced installers, such as Safe Roof Systems, Inc. (SRS), which can recommend the most economical monitoring system. SRS has recommended and installed joist-monitoring technology in a wide variety of buildings—wherever heavy annual rain and snowfall are common. SRS installed the monitoring system in use at the Maryland State House, as well as the overload monitoring system in use under the PV solar panels at the METLIFE stadium in Philadelphia.
Learn more about the Flex-Joist™ Gravity Overload Safety System™.
New Millennium has partnered with Building Design + Construction to bring you online educational resources that can meet your ongoing educational requirements, while showing you ways to lower the costs of structural steel building design and construction.
Courses carry AIA LU credit and merit in most states the Professional Development Hour (PDH) for continuing education.
For example, a course now on the campus is on the subject of “Progressive Steel Joist and Deck Design” and is presented by way of easy-to-learn video instruction. The course takes a building owner’s perspective on cost and performance improvements through the use of a design-analytical and collaborative approach. The course earns 1.0 AIA Learning Unit or 1 PDH credit.
Other present or planned courses on the campus include such course topics as “Castellated and Cellular Beams,” the new “Flex-Joist™ Gravity Overload Safety System™” and “BIM-Based Steel Joist Design.”
Educational courses offering AIA and PDH credit and a depth of technical information are posted at the New Millennium “Steel Joist and Metal Deck Campus” published by the online Building Design Construction University: http://www.bdcuniversity.com/new-millenium