Intended to make a statement to their worldwide customers, the One Haworth Center renovation and addition was originally designed with a 54-foot tall cast-in-place concrete wall along one side of the portion of the building termed “the bookend.” This unusual part of the building resembles a bookend because of its sloped and planted green roof, and tapered shape in plan. Up to 8 feet of this concrete wall is located below grade, supported on a cast-in-place retaining wall that forms one edge of an HVAC tunnel below the slab-on-grade.
The design and construction team brought in an engineer with a specialty in Tilt-Up to facilitate the conversion of the cast-in-place wall to Tilt-Up; a value engineering conversion that ultimately saved the owner more than $200,000 and more than one month in the construction schedule. The original architecture incorporated reveals and form tie “cones” into the exposed finish for the cast-in-place walls; these elements were also cast into the Tilt-Up panels during construction.
Other unique architectural features include full-height diagonal windows and a sloped top on the panels. While the window layout provides much architectural interest, it made the conversion to Tilt-Up somewhat difficult. The window layout dictated that some panels would be less than 3 feet wide at their base and more than 16 feet wide at the top, a panel geometry that would be unstable for erection purposes. For this reason, in several instances, multiple panels were temporarily tied together across the windows to create panels that could be erected safely.
To accomplish this, temporary recessed horizontal concrete beams were added across the openings. These tie beams also acted to transfer the lifting forces from one side of the diagonal opening to the other, thus minimizing the differential deflections between the two sides of the panel during erection. Overcoming the effects of a full-height vertical depression in some of the panels, which reduced the structural thickness down to 5.5 inches, was the final challenge.
This LEED registered building is classified as NC Gold by the U.S. Green Building Council.
Holland, MI 49423
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