The Tilt-Up Concrete Association (TCA)—a non-profit international organization that serves to expand and improve the use of site-cast Tilt-Up as the preferred construction method—has announced a new largest spandrel panel on the Top Ten List. The new titleholder is the 125-foot-long spandrel panel for the NSA-8 Office and Hanger in Scottsdale, Ariz.
"We’re quite excited to learn about this project," said Jim Baty, technical director of the TCA. "Not only does it evidence the ability of project teams to accomplish ever-increasing feats, it also places yet another example of a quality solution to what was thought to be a very difficult program type for Tilt-Up to achieve."
The owner selected Tilt-Up for this project to achieve an industrial-type look that features concrete, metal panels, and rivets with a modern twist. "The large spandrel panel was necessary, because the hanger door required a header over the top for the roof connection," said Steve Rafalski, project manager/estimator for Jones Concrete Construction, LLC of Phoenix. "Further, the owner wanted to keep the appearance of the concrete Tilt-Up panels consistent with the rest of the hanger. The large spandrel panel was the best way to accomplish the proper connection and provide the desired look."
Presenting several challenges, the large spandrel panel had to be engineered for top picks only because of the extensive rigging. Crews had to bring in a 70-foot major bar and then use two smaller 30-foot minor bars underneath it. On a typical panel, the 30-foot minor bar would be used as the major bar. Further, the crew faced obstacles with the crane. Located at an airport, several height restrictions of the boom of the crane were in place. Crews had maxed out the cable because of the restrictions, total length of the rigging, height that the panel had to be set at, and the height of the panel. "We had only two feet to spare before the hook and block hit the shutdown sensor at the top of the crane, which left no margin of error," said Rafalski.
The site was confined by private property, taxiways, and public streets, which required precise coordination. The building layout did not provide much usable slab space to place panels, so casting beds were used and panels were stack cast, which limited space on the site for crane. A 300-ton crawler crane was utilized, because it was able to pick up panels from just a few select places, because crews could not get next to the building on all four sides.
Comprised of 43 panels (10 of which are spandrel panels), the hanger is 11,000 square feet and the two-story office is 6,000 square feet. Still under construction, the project should be complete in April 2008. This complex project demonstrates the importance of pre-planning and pre-pour checklists.
"Pre-planning was crucial on this project to ensure that we had a usable erection sequence," said Rafalski. "Input from the Tilt-Up hardware supplier, crane operator, project general contractor, and structural engineer made for a much smoother job."
To learn more about other projects on the TCA Top Ten List visit www.tilt-up.org/topten/default.htm.