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THE 2020 EXCELLENCE IN STRUCTURAL ENGINEERINg

PROJECT SUBMISSIONS


Co|Lab

Simpson Gumpertz & Heger, Inc.



Capitol Crossing Pedestrian Bridge

ARUP


DC Water Headquarters

SK&A Structural Engineers, PLLC


Merriweather Crescent A-1 Office Building

Rathgeber/Goss Associates


655 New York Ave

KCE Structural Engineers, PC


International Spy Museum

Smislova, Kehnemui, & Associates, PA


Liz Donohue House

Meyer Consulting Engineers Corporation


3431 13th St NW

Elhert Bryan


1701 Rhode Island Avenue

SK&A Structural Engineers, PLLC


Carnegie Library Redevelopment

Silman


McCormick Headquarters

Thorntan Thomasetti


Calvin Coolidge Senior High School

A+F Engineers


400 N Capitol St, NW - Column Removal

Rathgeber/Goss Associates

C&O Canal Locks 3 & 4 Rehabilitation

McMullan & Associates, Inc.

Co|Lab

Falls Church, VA

Simpson Gumpertz & Heger

New Construction Under $25M - Merit Award

The Co|Lab is the first completed mass timber building in Virginia and serves as a showpiece for emerging technologies. The building is  expected to be net-positive, drawing energy from  a photovoltaic array supported on a steel rooftop canopy. Inside, two-story-tall areas offer space for building systems/component mockups and experiments, while rooftop dunnage platforms provide a structure for testing vegetative roofing and other assemblies in the local environment.  

The structure needed to accommodate large, open bays that HITT envisioned for the facility. By  combining CLT with glulam framing, the design team was able to achieve an efficient and attractive  structure for the Co|Lab while meeting the sustainability and aesthetic goals established by HITT.  The design uses CLT for all elevated floors and the roof, with a gypcrete topping on the CLT floors  to reduce sound transmission and vibration. CLT was also used for load-bearing and shear walls. 

By collaborating with the design and fabrication team, SGH developed creative beam and column  connections that are concealed and inherently fire-resistant. The design and detailing for the  framing and connections relied heavily on the intuition of experienced structural engineers, the past  experiences of the fabricator, and the skills of the contractors.  


Capitol Crossing Pedestrian Bridge

Washington, DC

ARUP

New Construction Under $25M - Outstanding Project Award

The Capitol Crossing Pedestrian Bridge is a new,  architecturally exposed, fully enclosed, structural steel bridge designed by KRJDA with collaboration with Arup to create forms that highlighted the fundamental structural behavior of its gravity and lateral systems.  

Envisioned originally as a double helix in elevation, the primary bridge trusses were rationalized  to reflect purer structural forms. Each of the two primary trusses is composed of a tied arch and  an opposing tied catenary. Structural sizing of the bridge is reflective of the forces in the arch and  catenary, allowing the tension only catenary to utilize a smaller diameter circular hollow section  than the compression only arch. The intersections of each of the bridge’s component parts required  detailed connection design; tight collaboration between engineer, fabricator and erector; and  precision welding and craftsmanship to preserve the architecturally exposed steel aims of the project.  Vibration performance was of critical importance to the projects developers as this bridge formed an  interior link between office lobbies. Arup was able to seamlessly specify and coordinate the location  of two tuned-mass dampers at the bridge’s mid and quarter points. These dampers allowed for  a reduction of overall human perception to footfall vibration by up to four-fold over the baseline  strength design of the structure.


DC Water Headquarters

Washington, DC

SK&A Structural Engineers

New Construction Between $25M - $75M - Outstanding Project Award

The DC Water and Sewer Authority Headquarters is a state-of-the-art facility on the site of the O Street Pump Station in Southeast DC. This site was challenged with preservation of site-lines,  setbacks from the Anacostia River, and the presence of the pump station that was required to remain operational. The limited remaining site area required  an innovative design with the new headquarters built over, and partially encapsulating the pump station. 

The design for the new 145,000 SF, six-story structure utilizes a traditional structural steel system with  composite horizontal framing. To support construction over the existing pump station, SK&A’s solution  integrates two long-span, multi-story structural steel trusses carrying nearly half of the building. The  trusses include a 210-foot, five-story truss spanning east-west over the south side of the pump station  and loading dock, and a perpendicular two-story, 90-foot truss over the east side of the pump station.  SK&A worked closely with the construction team to evaluate erection processes, and coordinate  the sequence of slab placement to control deflections. Other structural challenges in the project  included stepped columns along the south façade to respect the increasing building projections,  and coordination with significant below grade utility congestion limiting locations for foundations.  Evoking the fluid shape of water, the project is the perfect addition to the neighborhood, and the  challenging structural solution required to allow the introduction of a fantastic modern facility.


Merriweather Crescent A-1 Office Building

Columbia, MD

Rathgeber/Goss & Associates

New Construction Between $25M - $75M - Merit Award

Merriweather Crescent A-1 constructed on a  curved, narrow, sloping building site in the Merriweather District of Columbia, Maryland is a 13 story, 325,000 SF LEED Silver office building by Howard Hughes Corporation. The building provides retail, fitness area, restaurant and office space. In addition to traditional office space there is a private 2,600 SF exterior terrace on the 12th floor as well as both interior and exterior Penthouse  Level amenity space for all tenants. The structure consists of 5 1/4” lightweight concrete slabs  on composite metal deck supported by structural steel beams and columns. Foundations are of  traditional spread and mat designs on rock strata. The lateral load resisting system is designed as a  combination of steel braced frames around the building core and moment frames along the building  perimeter. Rock anchors were required for uplift due to the offset core and were drilled up to 55ft  into the rock below. Steel hold-down frames were designed to transfer the uplift forces from column  to anchor. RGA provided the contractor with an early release steel package 6 weeks prior to the  team’s 100% CD and in the midst of foundation construction and delivery of steel to the site they  redesigned a portion of the 11th, 12th, Penthouse and Penthouse Roof to accommodate changing  owner and tenant needs. The façade is designed with continuous ribbon windows set in precast bands  and includes a full height curtain wall that is supported by the Architecturally Exposed Structural Steel  feature stair on the south façade. 


655 New York Avenue

Washington, DC

KCE Structural Engineers

New Construction Over $75M - Merit Award

655 New York Avenue was a Fast-Tracked 1,016,000 SF structure spanning a full city block in each direction consisting of a segmented, tied down, pressure mat foundation with conventionally reinforced slabs up to the mezzanine level and post-tensioned concrete slabs with spans of up to 44’ feet above that. There was major use of heavy timber construction, plywood and steel fitch beams, and composite and non-composite structural  steel. The project was originally only located on the East end of the block but it was doubled in size  to the full block during construction.  

This development incorporated 19 historic buildings into the new structure, including moving two  existing historic buildings to mats supported on pile foundations which were then to be excavated  under, and lowering the foundations to add up to five sub-basement slabs under six existing  buildings. It included bracing of historic facades, underpinning of historic buildings, a two-sided  excavation surrounding the 7th Street historic buildings, installation of micropiles from grade within  an existing building in a top-down construction to be encapsulated in concrete to support the existing  4-story historic buildings in place with excavation and mat and floor slab construction installed as  encapsulating the supports in concrete, laterally bracing three levels underneath. 


International Spy Museum

Washington, DC

Smislova, Kehnemui & Associates

New Construction Over $75M - Outstanding Project Award

Designed by renowned architects, Rogers Stirk  Harbour + Partners, and local architects, Hickok Cole, the International Spy Museum at L’Enfant Plaza in Washington, DC is a 130,000 SF, distinctively-designed steel building with museum exhibition, office, retail, classroom, and event spaces. 

The building’s innovative design incorporates exposed, “L-shaped” red-painted columns constructed  from grade 50 steel plates along the south and west faces that slope and are part of the building’s  gravity load carrying system. The glass veil lines the west edge of the building and is supported with  gravity and lateral connections attached directly to the sloping red columns. Within the space of  the glass veil, there is an intricate series of monumental stairs and platforms constructed from AESS  members of varying shapes and profiles.  

The museum is built on top of an existing four-story concrete structure which remained occupied  throughout construction. Existing concrete columns were strengthened with post-installed concrete  jackets uniquely designed to minimize disruptions to existing spaces below. Existing footings were  strengthened with micropile installations and footing enlargements. The building’s design is tailored  to present new state-of-the-art exhibits and interactive installations to promote public understanding  of intelligence and espionage.


Renovations Under $15M

Liz Donohue House

Washington, DC

Meyer Consulting Engineers Corporation

Renovations Under $15M - Merit Project Award

Liz Donohue House preserves a semi-historic 1920’s construction using modern design techniques and construction materials. This restoration project consisted of two adjacent, nearly identical 16,500 SF apartment buildings with different floor elevations. Each building was three stories plus partial crawlspaces, and was comprised of a kaleidoscope of different framing materials and configurations.  

The project involved a complete gut renovation, modernization, vertical expansion (both up & down)  and connecting the two buildings. Structurally, the challenges included: Removal of existing concrete  columns by installing a complex arrangement of through-bolted HSS beams sandwiching existing  concrete beams, supported by steel columns on new concrete footings; Systematic underpinning of  existing basement walls and removal of approximately 1500 cubic yards of soil to allow for lowering  and combining of existing basements and crawlspaces; Reinforcing of existing wood & steel floor  joists and beams; Construction of four-story steel framed walkway and elevator tower adding mobility  between the buildings; Construction of a partial new floor framed with steel, light gage metal, and wood.  The Liz Donohue house is admirably fulfilling its intended purpose of restoring hope and dignity to  the thirty-six families by SOME (So Others Might Eat) - an interfaith, community-based organization  that endeavors to break the cycle of homelessness by providing services, such as affordable  housing, job training, treatment, and counseling, besides food and clothing, to individuals in need. 


3431 13th St NW

Washington, DC

Ehlert Bryan

Renovations Under $15M - Outstanding Project Award

Ehlert Bryan was tasked with the challenge of  converting an existing church sanctuary into a three-story residential apartment building. Almost every major component of this project required a unique structural solution. The existing roof structure consisted of several large wood framed trusses, which were required to remain in place while their ends, interior web members, and supports were removed. Custom steel brackets, steel tension rods, and wood beams were used  to restore the structural integrity of the trusses by converting them into a tied rafter system, all while  the surrounding portions of the trusses and the roof remained undisturbed. Beams were designed to  transfer these modified trusses to supports within the new architectural layout.  

At the exterior of the building, full-height, vertical slots were cut through the exterior masonry walls  throughout the façade. Ehlert Bryan developed support for the remaining wall segments with steel  frames at the jambs and wood tie beams at each floor level.  

An elaborate temporary shoring structure and sequence had to be developed to support the trusses  and exterior walls during construction. Ehlert Bryan provided a creative conceptual design to allow  the contractor to shore, demo, and build the new structure around these elements without disturbing  the portions to remain.


Renovations Between $15M and $40M

1701 Rhode Island Ave

Washington, DC

SK&A Structural Engineers

Renovations Between $15M and $40M - Outstanding Project Award

The 1701 Rhode Island Avenue project  involved the repositioning of an existing YMCA building into a 104,000 SF office building. The existing building was originally designed to house athletic functions. The design team was challenged to repurpose the existing structure into office space while maintaining enough of the existing structure to utilize the original, and more advantageous, zoning aspects of the site. 

To provide the most desirable office space possible, the stacked fitness program spaces were  demolished, and a new multi-level composite steel structure was erected in its place. The surrounding  areas on two sides of the reconstructed portion were preserved for reuse. A new concrete shear  wall lateral system was introduced to provide additional means of stair egress and new vertical  transportation systems for the increased occupancy. This structural system provided for long-span bays  of up to 38 feet for the office occupancy, with an expansive glass curtainwall along the exterior façade. 

Throughout the construction process, SK&A worked closely with the general contractor to provide  a zone-based approach to demolition and implementation of new work. This allowed the team to  minimize the amount of temporary shoring and to maximize the free work area, helping to alleviate  the confines of working within an existing structure. Together with the architect and owner, SK&A was  able to fully reposition the existing structure and provide a modern, expansive office environment.


Carnegie Library Redevelopment

Washington, DC

Silman

Renovations Between $15M and $40M - Merit Award

Anchoring DC’s bustling Mount Vernon Square, the historic Carnegie Library is deeply rooted in the city’s history. Opening in 1903 as the first desegregated public library in DC, it was used as the central public library for almost 70 years. In 2016, Events DC, who administers the building for the City of DC, announced an extensive historic restoration project and design of a premier flagship store. 

The Carnegie Library Renovation project involved renovating and revitalizing the Beaux-Arts style  building by carefully preserving the historic facades and restoring early 20th-century detailing. The  new space was designed to be a center for the community to learn, discover, and create, preserving  Carnegie’s vision of a public and free space for all. The interior preservation strategy relied on  identifying hidden historic shafts to invisibly integrating contemporary building systems and lighting,  while integrating contemporary features. The cloistered library space was tran SFormed into an open  and engaging space, welcoming visitors to experience the next century of learning.  

With the addition of a custom skylight above the historic light well, and the removal of non-original  slab infill, natural daylight was returned to the central atrium. Two bridges, flanking the atrium’s  second floor, give visitors access to the “DC Hall of History” and view into the double- height atrium.


Renovations Over $40M

McCormick Headquarters

Hunt Valley, MD

Thornton Tomasetti

Renovations Over $40M - Outstanding Project Award

McCormick & Company’s new headquarters was  designed to help make their vision of becoming a talent magnet a reality. The $170-million project houses more than 1,000 employees in a six story, 350,000 SF building. The headquarters features a glass-walled atrium, open and light filled workspaces, an employee wellness center  and a gourmet café showcasing McCormick’s products and flavors. The existing building structural system consisted largely of steel construction  with a combination of non-composite and composite floor slabs. The foundation system consisted of  spread footings and a slab on grade. 

In addition to replacing the existing façade and modernizing the existing building services, a  combination of retrofitted existing structures and new ones were designed at the ground level to  provide kitchen, conference and dining spaces. The project also added a full height atrium, which  required demolishing a 3,500 SF area on every floor. A floating cantilever stair now extends almost  17 feet into the atrium, creating a focal point for the space. To further enhance the headquarters feel  of the building, the design team relocated the mechanical plant out of the existing penthouse to open  that floor up to be an executive level with sweeping views of Hunt Valley. A fast-paced design and  construction schedule turned McCormick’s project vision into a reality when the building opened in  October of 2018.



Calvin Coolidge Senior High School

Washington, DC

A+F Engineers

Renovations Over $40M - Merit Award

Coolidge Senior High School is the complete modernization of the 1940 existing facility for DC Public Schools. Comprising 12,126 SF of exterior additions, 32,000 SF of interior infill additions and 319,000 SF of comprehensive interior renovations, the project enclosed two open courtyards for new open common spaces,  

highlighted by a glass roof. Each infill is a 57 ft tall steel structure on micropiles, supporting a roof  with four large pitched skylights that leave most of the roof open for natural light. The Courtyards  feature four tree columns, composed of large round HSS that splits to four smaller round HSS to  support the roof framing. Part of each infill is a 3-story structure that houses classrooms and an  Atrium open space at the top floor. 

The modernized facility introduced the Ida B. Wells Middle School addition, a community health  clinic and a day care center to the site, as well as facility and site enhancements to the Frank Williams  Activity Center, the exterior field and school grounds. The two schools will share some program space  such as the auditorium, clinic, cafeteria and library, but will otherwise be operated separately. 

Coolidge High School is eligible for listing on the National Register of Historic Places and the project  is registered for LEED Gold.


Specialized Structural Elements

400 North Capitol St NW - Column Removal

Washington, DC

Rathgeber/Goss Associates

Specialized Structural Elements - Merit Award

RGA designed and detailed custom fabricated  steel transfer girders for the removal of two existing concrete columns between the 1st and 2nd floor at 400 N Capitol St, NW. The column removal created an open space with flexibility for the approximately 10,000 SF studio for NBC News.  

The girders span approximately 42 feet and support 7 floors and a roof. All levels above and below remained occupied during construction.  To avoid disruption of the floors above, total deflection was limited to ½”. Girders were monitored  before, during and after the column cuts. The existing structure required two transfer girder designs.  The first was designed with two 40” deep custom fabricated channels, one on each side of the  column to support a 560 kip load. The second was adjacent to a slab step. For this condition one  48” deep channel was designed to support a 400 kip load. This member was designed to locate the  shear center at the column centerline to limit torsion. 

To avoid shoring, girders and plates were fully installed prior to column cuts. Epoxy was injected to  fill voids at thru bolt holes and provide full concrete bearing. The thru bolts transferred column loads  to girders and existing support columns. Plates with thru bolts were installed to reinforce the existing  columns and limit deflection of the transfer girders. CFRP was utilized to increase the capacity of  existing columns below. RGA analyzed the existing mat foundation for the redistribution of loads.


C&O Canal Locks 3 and 4 Rehabilitation

Washington, DC

McMullen & Associates, Inc.

Specialized Structural Elements - Outstanding Project Award

McMullan was the SEOR for the rehabilitation  of two stone masonry locks constructed in 1832  and located between 30th and 31st Streets NW Washington DC. Lock No. 3 required complete reconstruction to address tilting walls due to deterioration of its timber foundation. The timber lock gates were removed; the 15-foot-high ashlar laid stone masonry walls were disassembled, marked, and temporarily stored; and the timber  lock foundation was removed. After a concrete mat foundation was installed, the lock walls were  reconstructed with the face stones in their original position. Lock No. 4 required repairs to address water  leakage through the masonry and deteriorated timber gates. Repairs included partial replacement of  deteriorated stones, repointing, and replacement of the wood lock gates and associated hardware.  

A key challenge was the requirement to restore both locks reusing as much historic material as possible.  During initial investigations, many of the face stones were found to have cracked or delaminated.  Methods for repairing face stones were developed as well as specifications for the disassembly,  cleaning, and temporary storage of stones to minimize further damage. To quantify the repairs for  bidding, photos of existing lock walls were projected onto an elevation plane with individual face  stones requiring repair identified. As each stone was removed and closely inspected, a decision was  made if the stone should be replaced or repaired. Measurements taken during disassembly were  found to be similar to those anticipated, minimizing the need for new backing stone.



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