The project: The Armature Works development in Washington, DC’s NoMa/Union Market area comprises three towers—two residential buildings and a hotel—rising from a five-story podium on a former industrial site. Alongside The Morrow Hotel with 200 rooms and the Le Clou restaurant, the 12-story Rigby (172 units) and Market House (468 units) residential buildings provide luxury amenities including a pool, fitness center, rooftop bar, and outdoor terrace, for residents. The podium connects the three towers and includes a second-story central courtyard; three-story, below-grade parking structure; and 60,000 square feet of two-story retail.

The goal: Convert a former industrial site into an urban center including residential, hospitality, retail, and parking.

Design approach: IMEG structural engineers were proactive and closely collaborated with all project team members to ensure project challenges were solved quickly and without impact to the construction schedule while also staying true to the architect’s design and aesthetic.

Challenge: The project site’s location and adjacency to the NoMa/Gallaudet Amtrak train station posed unique challenges to mitigate vibrations from the trains and avoid interfering with the existing foundations for the catenary structures overhead. Solution: Permanent basement retaining walls using lateral stress from the Amtrak abutment were designed to provide a robust foundation system. The basement walls were designed to span vertically in most instances, but where vertical spans were excessive due to large shaft openings, horizontal beam members were added to cut down the span.

Challenge: Prep the site for future integration with the nearby New York Avenue Red Line metro station. Solution: Structural engineers designed a pedestrian portal beneath the Market House building and a retaining wall with a knockout panel to facilitate the construction of a future tunnel, minimizing the need for extensive redesigns whenever metro integration begins.

Challenge: Innovative design for the open pedestrian portal space in the Market House residential building that provides structural support and contributes to the aesthetic of the building. Solution: Long spans were achieved using 74-foot transfer girders at the fourth floor, supported mid-span by steel V-columns, which are supported on 9-foot-diameter caissons. Concrete tie-beams spanned between the steel V-columns, running perpendicular to the transfer girders, and were designed to distribute the axial forces at the top of the steel V-columns. These tie-beams were also designed with beam penetrations allowing the conduit and plumbing to pass through the soffit of the pedestrian portal and connect the north and south portions of the Market House residential building with plumbing and electricity.

Challenge: Accommodate a variety of special project features. Solutions: Structural design solutions included:

  • Intricate steel design elements for a distinctive water feature
  • NanaWalls opening The Morrow Hotel rooftop bar indoor space to the outdoors
  • Telescoping partitions for the conference room
  • Concealed rebar to support two monumental stairs, a concrete stair in the hotel and a steel stair in the Market House residential building, so that the stairs appear as if unsupported
  • Podium courtyard design to support landscaping, pergolas, varying slab depths to accommodate different soil depths and finishes, and sidewalk sculptures

Challenge: Optimize the project design to enhance the building aesthetics while also reducing overall embodied carbon. Solution: Engineers pulled columns inward from the exterior edge, resulting in thinner slabs, and utilized shear stud reinforcing in place of concrete drop panels. All three buildings are LEED Gold certified and include green roofs and solar panel systems. The project also recycled materials from the original Armature Works industrial site and construction waste.

The outcome: IMEG’s collaborative approach ensured the timely resolution of challenges and adherence to the developer and architect’s vision for the conversion of an underutilized industrial site into a mixed-use and transit-oriented community.