Phoenix— The Post-Tensioning Institute, a nonprofit organization for the advancement of post-tensioned, pre-stressed concrete design and construction, has announced the winners of its 2008 awards competition.
In the Residential Buildings category, engineering firm Cary Kopczynski & Company was selected for the Cosmopolitan in Seattle. With stunning views of Elliot Bay, the Olympic Mountains and downtown Seattle, the Cosmopolitan tower boasts a wide-open design thanks to post-tensioning. A concrete shear wall core, wrapped by a 6-foot-wide thickened drop-head slab on three sides, allows 8-inch-thick post-tensioned slabs to span almost 40 feet from the core to the building's perimeter, eliminating interior columns.
High-strength concrete eliminated the need for ductile frames while also minimizing wall size and maximizing views. Mechanical ductwork, water supply lines and most building utilities were run through the post-tensioned slabs, allowing for open ceilings in the residential units. Other project team members include M.A. Mortenson (contractor) and Central Steel (post-tensioning supplier).