3100 Clarendon Boulevard Building Modifications

Built in 1985-1986, the 14-story, 260,042 sf office building at 3100 Clarendon Boulevard, across from the Clarendon Metro plaza, underwent an extensive interior and exterior renovation in February 2014. SK&A’s Repair & Restoration Division provided repairs to the existing building’s main façade and various structural slabs, and designed the new monumental stairs.

The façade repairs consisted of the removal and replacement of the existing stone cladding on all four sides of the building with new aluminum glass cladding. SK&A provided deflection, load, and design criteria for the support system of the new cladding. Existing structural slabs were extended on the east side of the ground floor and second floor level. SK&A also designed new cutouts for two new elevators at the center and west sections of the building. In addition, a new steel dunnage was designed to install mechanical equipment on the third floor plaza and penthouse roof.

The lobby area renovations included a new second floor level and monumental stairs. The steel and glass stairs were a challenge to install due to the sharp angle of the stairs. One set of stairs connects the ground level to the Metro level and another set of stairs connects the ground level to the second floor level.

The project was awarded the Juror’s Citation in Commercial Interiors at the 2016 Design Awards presented by the AIA Northern Virginia Chapter.

L’Enfant Plaza East & West Retail Renovations

Located in Washington, DC’s southwest quadrant across from the National Mall and Smithsonian Museums, L’Enfant Plaza is a massive mixed-use, commercial complex of multiple mid-century buildings originally constructed in the 1960’s.  The complex features office/commercial and governmental buildings, a hotel, an underground shopping mall and parking, as well as a major subway station.  The overall complex has been undergoing an extensive renovation and redesign, including the redevelopment of the retail mall as well as the existing L’Enfant Plaza hotel and an office building.  A new 600,000 sf office building will also be constructed in the center of the plaza. 

The retail renovation projects included modernization of the existing underground retail mall, the development of a new glass atrium providing access to the underground retail corridor, and structural strengthening at the promenade and plaza levels to accommodate the future nine-story office building.  The strengthening work for the office building was conducted concurrently with the retail renovation to allow retail operations to continue uninterrupted during construction.

For the strengthening portion of the project, a cost-effective demolition concept was devised involving almost no re-shoring of the existing slab.  New concrete framing was constructed over an existing auditorium occupied by the National Transportation Safety Board (NTSB).  To construct the framing, SK&A assisted the contractor in developing a steel formwork system using new and existing columns for support.  A grid of compression beams was also designed to support the plaza layout and future office building concept.  

The large glass atrium portion of the project is composed of a series of steel moment frames.  Slip-critical bolts at the column-to-beam connection were used to accommodate the contractor’s preference for steel erection.  Additionally, the east stair spans between the promenade and plaza levels, with no posts beneath the landings.

The East and West portions of the renovation were designed and constructed as two separate projects.  The West project received an SEA-MW award in the $15-40 Million Renovation category in February 2015. 

200 Eye Street, SE

Built in 1957, this former printing facility was a five-story building that included a basement level over pile foundations.  In the early 2000’s, the building was renovated to house a telecommunications firm, which was never occupied.  Floors were filled in on all levels and structural column modifications existed on some floors.

Completed in 2012, the building was converted to office space for occupation by various DC Government agencies.  The lowest level was converted to parking and a new two-level parking garage was constructed adjacent to the existing building on the east side.  Lateral stiffness of the building was enhanced using steel braced frames installed before removing the existing precast façade.  New elevator shafts and interconnecting stairs were framed at existing floor plates. Structural services also included the evaluation of existing structural elements for new loading, green roof evaluation and local strengthening.

The project has received the highest level of LEED certification–Platinum, as well as numerous awards of recognition.

733 15th Street, NW (The Woodward Building)

Complete restoration and conversion of a circa 1910 steel and concrete-framed 11-story office building (including one basement level) into a residential apartment building.  Historic restoration activities included modifying floors constructed of terra cotta flat arches with concrete fill, and rehabilitation of the multi-wythe brick façade.  The façade materials also included stone at the lower levels and terra cotta at the uppermost levels.  Several columns were removed in the basement to facilitate parking.  Hydraulic jacks were used to pre-deflect six new steel transfer girders at the ground floor used to replace the columns.  Stairs were reconfigured throughout, terraces added to the roof, and two vehicular elevators added to access the below-grade parking.

The project was awarded the 2009 Outstanding Project Award for Excellence in Structural Engineering by the Structural Engineers Association of Metropolitan Washington. 

2000 N Street, NW Plaza Renovation

This project entailed the renovation and conversion of a hotel facility into a rental apartment complex.  Prior to commencing the general building renovation, repairs to the garage, as well as plaza strengthening and plaza waterproofing were required. Repairs included: waterproofing and repair of the plaza deck over the garage, structural analysis and strengthening of the plaza deck to support the proposed new plaza landscape design, along with full depth wall-to-wall removal; and replacement and waterproofing of the below-grade parking deck.

SK&A’s structural analysis determined that many areas of the plaza slab needed varying levels of reinforcement in both positive and negative movement areas.  Strengthening of the plaza deck involved both carbon fiber reinforcement and the casting of new concrete beams into the plaza deck, which extended both above and below.  A total of 21 new concrete beams were cast into the plaza slab.

Additional work included the installation of new rooftop unit steel-frame supports, masonry planter wall construction, plaza drain installations (determined from plaza deck flood testing results), and the demolition and reconstruction of two balconies to provide a new curved shape matching the plaza design features.

King Street Station II Plaza Renovation

The King Street Station complex is bounded by Duke Street, Diagonal Road, and Reinekers Road in Alexandria, Virginia.  The property includes five buildings under separate ownership, which all share a common elevated plaza deck. SK&A’s Repair and Restoration Division provided waterproofing and protection as well as asphalt repair and replacement consulting for the plaza renovation project.  

Repairs included stripping the entire plaza down to the structural slab and applying a hot rubberized asphalt waterproof membrane followed by the restoration of plaza pavers, fountain planters, and asphalt. Project specifications and construction monitoring was also provided for 8,000 sf of hot mix asphalt paving, which was placed over the waterproof membrane and protection board in the plaza area to allow for limited vehicle access through the plaza area.

Kaiser Permanente Regional Headquarters & Laboratory

SK&A has performed structural engineering services on numerous projects for Kaiser Permanente, including its 168,000 sf medical office headquarters in Silver Spring, a new medical office building in Manassas, VA, the Regional Laboratory facility in Rockville, and the Silver Spring Data Center 2.

  • For the regional laboratory, an existing two-story medical office building was adapted for reuse as a laboratory facility.  The structure has concrete masonry unit (CMU) load-bearing walls supporting a steel bar joist and steel-framed roof and floor deck.  Sections of the 2nd floor and roof were strengthened to increase their load carrying capability, to suit laboratory and library usage, and to handle new roof-mounted equipment.  The project also included a new building addition at its northwest corner, and several new in-fill elevated floor areas.  The existing first floor of the building was demolished and lowered in its entirety to accommodate access flooring.  Existing masonry walls were structurally modified, and new openings incorporated into the walls.
  • In addition, since 1994, SK&A’s Repair and Restoration Division has provided engineering services on over 50 Kaiser projects including garage repair, expansion joint replacement, load evaluation, supplemental equipment support framing designs, façade repair, and general structural condition assessments.  SK&A also provided design and field inspection of a rooftop transfer girder installation, facilitating the removal of a ground level column in a conference room at the East Jefferson facility.

Children’s National Medical Center Additions and Renovations

From 1986 until today, SK&A has been the structural engineer-of-record for all of the new construction, alterations, and structural retrofit work that has been or is being built at the Children’s National Medical Center (CNMC) in Washington, DC.

Gross area of new floor design undertaken at CNMC by SK&A, either constructed or under construction, consists of approximately 570,000 sf of hospital, laboratory, administrative, and support spaces (exclusive of service levels within the hospital), and 230,000 sf of structured parking.

The various expansions of the CNMC have generally been in the form of lateral tower additions to the main building, several vertical extensions of the main hospital tower at several stages, and construction of various support faculties, utility upgrades (including a full retrofit of electrical systems), new rooftop heliport, new laboratory spaces, a new MRI unit on the second floor, and a new medical office building.

Whole Foods Market, P Street, NW

A 40,000 sf urban supermarket, with below-grade parking under the store, and roof-level parking over the store.  Separate circular ramps connect the under/over parking levels to street level.

The market’s truck loading/delivery dock is also located over underground parking.  Parking is provided for 165 cars: underground for employees and customer parking at roof level.  A later renovation to the store included a large mezzanine level.

IMF Concordia, 1250 New Hampshire Avenue, NW

Renovation of an existing apartment building into an extended stay hotel for International Monetary Fund guests.  Originally constructed in 1965, the building is centrally located between Dupont Circle and Washington Circle, and features 121 guest suites with fully equipped kitchens, a fitness center, and rooftop pool.  The project scope included extensive structural modifications to the existing cast-in-place concrete structural system. 

Structural modifications included demolishing the elevator core and rebuilding it into a larger configuration at a new location.  Two new stair towers were added within the building footprint to meet current egress requirements.  The relocated elevator core and added stair towers are supported on new mini-pile foundations designed to incorporate the existing footings and minimize demolition. 

Concrete structures were added at the roof level over the new elevators and stairs.  The entire façade was removed and replaced with a curtain wall and cast-stone system, and includes a new entrance canopy.  The renovated building has achieved LEED Gold certification.