Waterfront

Situated along Washington DC’s Southwest Waterfront, the Wharf Parcels 6&7 also known as 670 Maine and 680 Maine, consist of two 11-story, Class “A” office buildings (480,000 sf), which are part of the phase two development at the Wharf DC.  The office buildings consist of concrete framing with a post-tensioned concrete slab over a two-level underground garage extending under multiple towers.  

The hybrid foundation system is comprised of multiple foundation solutions, spanning over the Washington Metropolitan Area Transit Authority’s (WMATA) green line metro tunnel.  The transfer mat over the tunnel with rigid anchor and drilled displacement piles create an innovative solution to control the settlement.  Also, vibration isolation was included to eliminate any vibration and noise for the tenants. 

To create a maximum unobstructed interior space within the buildings, columns were spaced up to 42 feet and 15 feet cantilevered slabs all around the perimeter of floor plates guaranteed open and continuous views through the sophisticated curtainwall and glazing system.  An innovative shallow 81 feet concrete post-tensioned bridge connecting the two buildings with an oculus in the middle created a dramatic view while the interior open space with the bridge was used as the continuation of the office space.  

Located in the Capitol Riverfront’s Ballpark District, 1000 South Capitol Street is a 13-story, 350,000 square foot U-shaped residential building with 244 apartments, 14,000 sf of retail space, and a 225 space below-grade garage.  The rooftop features a resort-style deck with an infinity-edge pool, cabanas, and lush landscaping.  Additional amenities include a fitness studio, wine bar, courtyard gardens, podcast studio, screening room, billiards room, and pet spa.

A structure of architectural beauty and engineering excellence, the building features dramatically angled floor-to-ceiling windows, a landscaped terrace over the rear portico, and numerous cantilevered balconies.  The building design utilized an undrained (bathtub) basement, supported by auger cast pile foundations, and hydrostatic slabs with integral pile caps.

Situated on the waterfront, this five-story office building provides breathtaking views of the Potomac River.  Cantilevering out over 35 feet, Parcel 10 also known as the DCX Office Building, has been compared to a floating jewel box extending to the Potomac River.  Even more striking, the structural profile at the ends of the cantilevered floors is only eight inches thick.

The challenge to the team was simple: create a light, floating five-story office building with 35-foot cantilevers.  SK&A worked closely with the architect early on for studies that would be acceptable to the architectural program.  While numerous concepts with steel and concrete were done, at the end it was determined that a two-way post-tensioned high strength concrete (7,000 psi) slab with drop panels provided both the thin structural profile and long cantilevers, which the architect envisioned.  To achieve a thin profile at the ends of the perimeter, the drop panels were tapered in thickness.  A 5’-0” perimeter of a “no drop panel zone” was created to allow the thin profile at the exterior of the building, while also allowing the glass façade to extend up from floor to floor without the use of spandrel glass.  

Situated on the edge of the Potomac River, the Wharf Parcel 8 also known as the Tides Apartments and Pendry Hotel, pushed the boundary of sloped buildings.  With 13 stories of hotel on the west side and 13 stories of residential units on the east side, the U-shaped building creates unobstructed views of the Potomac River for both functions.  This was imperative to the architectural design of the building. 

Located directly over the underground METRO green line tunnels, the new foundations needed to adhere to the strict requirements of the Washington Metropolitan Area Transit Authority for building overtop of an existing operational tunnel.  A hybrid system of a mat foundation and spread footings were used to help reduce the surcharge on the tunnel below as well as create an economically efficient design for the foundations.  Noise and vibration from the tunnel below were also a concern.  An isolation pad under the mat foundation, spread footings, and columns were used to mitigate any noise and vibration from the tunnel below that would propagate through the first several floors of the building. 

Situated directly across from the new Washington Nationals Stadium, West Half Street is a 13-story residential building featuring a modern, high-end, canti-levered design with gradually alternating and descending outdoor terraces.  The building includes 465 apartments in studio, one- and two-bedroom layouts, 61,000 sf of retail on two floors, and multiple amenities such as a rooftop pool, penthouse lounge areas/clubrooms, and a central courtyard.  The aboveground structure sits atop a three-story underground garage with 329 parking spaces.  

The building was designed to be the crown jewel of the surrounding development area providing residents with unobstructed views of the baseball stadium and surrounding Navy Yard waterfront neighborhood.  SK&A worked with the architect to design a building that continuously rotated and twisted which allowed for these views.  To support the large cantilevers from the building face, Y-branch columns with tie-beams were utilized.  Strategically placed concrete shear walls resist the building’s natural tendency to twist and rotate under its own self-weight.  The Y-branch columns were also designed to support the ends of the ever-increasing cantilevers.

The completed design culminated into a graceful, functional, and exceptional residential structure that adds to the diverse architectural fabric of the Navy Yard waterfront neighborhood.  The building’s new residents will enjoy prime views of game-day action with personalized experiences of the surrounding ballpark atmosphere.   

Part of a 3.3 million sf mixed-use development situated along Washington DC’s Southwest Waterfront, The Wharf Parcel 3A also known as 800 Maine, is an 11-story, 233,000 sf Class “A” office building.  The office building is constructed atop a shared two-level underground garage occupying the entire project site.  The superstructure and underground garage are concrete-frame with conventionally reinforced floor slabs, reinforced concrete columns (typically 30-ft. apart), concrete shear walls, and select post-tensioned concrete components.

The building is also located in a section of the site where WMATA’s Yellow Line metro tunnel and air intake shaft conflict with the western side of the building’s columns and foundations.  To bridge over the existing WMATA structures, a solution was executed using underground concrete transfer girders over the tunnel and a two-story elevated steel truss between levels 2 to 4, which spans 90 feet. 

The SK&A team’s structural ingenuity and close collaboration with the owner, architect, and design builder ultimately delivered a visually appealing and structurally sound building, with WMATA’s structures intact and operational during construction.

SK&A provided structural engineering services for the design and construction of the new Thompson Hotel and Estate luxury apartment buildings.  The new buildings are located on parcel L of The Yards, a 42-acre mixed-use, waterfront redevelopment situated along the Anacostia River in Southeast, Washington, DC.

The buildings are designed with joint access between them and are constructed atop of  a shared, below-ground, two-level parking garage.  The project designs also included navigating around a large underground sewer line at the northern end of the site.

• The Thompson: The upscale Thompson Hotel is part of the Hyatt hotel portfolio.  The 10-story building includes 38 luxury suites, a restaurant at street level, rooftop bar, fitness center and meeting/event space.  
• The Estate: A luxury, high-rise apartment building with 285 residential units.  The building features ground floor retail and amenities such as, several community lounges (garden, media, work), rooftop swimming pool, indoor spa/whirlpools, fitness center, and pet spa.

SK&A provided structural engineering services for the design of DC Water’s new headquarters. The stylistic, modern facility is located on 2.75 acres, adjacent to the waterfront mixed-use development, The Yards, and the Washington National’s baseball stadium.  

The new building is a six-story, 150,000 gsf steel-frame structure with a fluid form. The building footprint was carefully shaped to develop a unique, site-specific solar response and consists of full-height curtainwall on the south, east, and west sides to take advantage of the scenic views, and gradually shifts to punched windows on the less scenic north side of the building.  The structure consists of a framed concrete slab-at-grade with six levels (five office levels and an accessible roof terrace) of composite steel construction.

The exterior facades feature a glass and aluminum curtain wall system on the south facade, and a “variegated green rainscreen panel system” on the north and west facades.  The building was constructed around and above the existing “O” Street Pumping Station, which maintained full operations throughout construction.  Foundations for the structure consists of below grade transfer elements and deep foundations.  As part of the landscape design, an exterior boardwalk and metal grating structure was implemented over existing tidal gates.

New mechanical equipment support and an enclosure were added on top of the existing pump station building.  New openings in the exterior walls at the ground floor  of the pump station facility provide a visual connection to the pump room from the new lobby.

Additional project features include an entry court, interactive exhibit space, and a boardwalk along the south facade.  The mechanical systems uses the pump station wastewater for heat recovery and rainwater from the rooftop will be collected in a cistern to use for toilet flushing.

Situated in Washington, DC’s Capitol Riverfront neighborhood, The Yards is a 42-acre, 5.5 million sf mixed-use redevelopment featuring residential, office, and retail spaces as well as restaurants and a public park.  SK&A provided structural engineering services for two residential buildings constructed simultaneously on Parcel O of the development.

The Bower, on Parcel O-1, is a 154,400 gsf, 10-story residential building with 138 condominium units.  The Guild, on Parcel O-2 is a 208,700 gsf, 10-story residential building with 198 units.  Both buildings feature ground floor retail, indoor amenity spaces, lobbies, green roofs, a public courtyard, and a shared two-level, underground parking garage with a flood-resistant design.

The buildings were constructed over WMATA’s Green Line tunnels, which required that structural analyses be performed to demonstrate the tunnels’ capacity and stability to resist the forces imposed by the unloaded condition during construction and the final condition when the buildings were completed.   

As a part of overall renovations to The Watergate Hotel, SK&A’s Repair & Restoration Division conducted a comprehensive condition evaluation of the iconic structure’s exterior envelope, including the building’s façade, roof, plaza, and balconies.  Designed in 1966, the contemporary building has 13 stories above ground with three levels of parking below.  The hotel is constructed of conventionally reinforced, lightweight concrete slabs used throughout, and the balconies are constructed of cantilevered concrete slabs.

The condition evaluation was conducted over several phases, including: schematic design/design development, 75% and 100% construction documents, and construction administration.  Examples of services provided during the evaluation include:

• Review of available, original architectural and structural drawings to determine construction details related to the façade, roof, plaza area, and various site elements including, but not limited to, the expansion joints.
• Site visits to visually examine the façade from the ground level, roof, and various balcony locations.
• Visual observation and documentation of the façade’s condition related to cracking and corrosion and visual examination of the roofing membrane’s condition and observation for the presence of moisture beneath the membranes.
• A sounding survey of the hotel balconies and other exposed structural systems.