Story

Skymark Reston Town Center, the tallest mixed-use residential tower in the Capital Region, is part of the next phase of the transit-oriented development that expands Reston Town Center in Fairfax County, Virginia. The 39-story development sits on top of a podium containing ground-floor retail, 44 loft-style residential units, and 80,000 square feet of office space across four stories. The tower offers 464 apartments ranging from studio to three-bedroom units, while a low-rise residential building features 44 artisan/maker loft-style units and townhomes with frontage along a new public park. The project also includes 12,000 square feet of active street-level retail and garage parking for 630 vehicles. A shared amenity space spans the fifth floor and features a communal kitchen and bar space for entertaining; a co-working space with conference rooms; and an outdoor pool deck and terrace. Construction of Skymark presented several unique structural and logistical challenges due to its height. Large "mega columns" at the perimeter of the floor plate and large shearwalls at the core of the floorplate had to be poured monolithically (ie. the entire floor and shearwall had to be poured in one pour each: a single pour for the floor and a single pour for the walls), which required detailed planning with the concrete supplier to ensure the local plant could meet the needs of the large pours. Due to significant wind loading on the tall structure, there were also large, custom-welded steel "link beams," constructed of 4-inch thick steel plates, that were coordinated with rebar in advance of the concrete pours and beam fabrication. These massive steel beams, which were up to 8-feet high and 13-feet long, were embedded inside the concrete shear walls. In addition, the building height and proximity to power lines precluded the ability to set precast above level 24 with a mobile crane. The team developed a solution to set precast on levels 25 to 39 by hand, using chain falls. Locations for chain fall holes were coordinated at the edge of the slab, so the precast could be lowered into place and set. The precast pieces also had to be sized appropriately so that they were not too heavy for the operation - a detail that was coordinated with the precast supplier. The high-rise construction also required detailed safety planning. Falling objects from a height of 40 floors can be catastrophic, and the wind speeds in the Reston corridor were considerable. The project team, including trade partners, developed several site-specific safety measures, including full-height safety netting around the entire perimeter of the building, cantilevered netting below an active deck being poured, and procedures to strap material/debris together and to columns in to mitigate falling object hazards.