Northwest Construction - (Page 2) Best of 2007 Washington Sheraton Hotel Addition Best Major Project (Tie) Project Overview The new $100 million downtown Seattle Sheraton Hotel expansion and renovation encompassed two phases: construction of an expanded ballroom and construction of a new, 25-story hotel tower. The ballroom phase included a complete demolition and rebuild of the Sheraton’s existing first-, second- and third-floor podium levels. The new tower, which is connected to the existing 34-story tower at the podium level, includes 430 new guestrooms. The project’s aggressive schedule could only be accommodated with an unconventional approach to the structural work that tied the new tower to the expanded ballroom. Certain vertical elements of the concrete tower had to be built out of sequence in order to be ready to receive the steel structure of the ballroom. Typical tower construction involves building walls, pouring an elevated deck and then continuing to incrementally build floors and walls until the structure tops out. In this case, crews had to run the new tower’s braced walls 30 to 40 ft tall to temporarily eliminate floors and other wall elements, in order to create a connection spot for the steel ballroom structure. This was the only way a tie-in between the two phases could be accomplished because the crews were allowed only a six-month window between major conventions to complete the expanded ballroom phase. Crews gained additional time elsewhere in the schedule using a unique column-hung forming system on the tower. With this system, the forms used to pour floor slabs are hung from the top of the structure’s columns instead of relying on support from the floor below. Because form supports are bolted to existing columns, the floor below does not carry the floor being poured. This eliminates the need for shoring and reshoring columns down through the building and opens up the space early for mechanical, framing and other trades. Project Team Owner Seattle Union Street Associates Architect Callison. Seattle Construction Manager CM&D, Seattle General Contractor Skanska USA Building Inc.Seattle Structural Engineer MKA, Seattle Electrical and Mechanical Glumac, Portland Landscape Consultant The Berger Partnership, Seattle The use of column-hung forming systems is relatively new to Washington. Skanska’s first use of this time-saving system was on the construction of the recently completed Lincoln Square mixed-use development in Bellevue, Wash. Innovation The Sheraton Hotel remained open and fully operational during the entire 22-month project. To achieve full functionality of the registration area, kitchen, guestrooms and other areas, crews broke the work into multiple small phases. 2 Northwest Construction 12/ 2007
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