Bank of America at One Bryant Park
Innovative systems combine to set a new, sustainable standard for high-rise buildings
By Ashley Kizzire
In a city famous for skyscrapers, one high-rise currently under construction is designed to stand apart from all others. Known as One Bryant Park, this high-rise office complex features one of the most structurally advanced designs in the United States—a design required to achieve the architects’ vision of a crystalline form; to accommodate pre-existing site conditions; and to accomplish height, strength, and security goals. A remarkable feat in architecture, structural design, and construction, One Bryant Park is poised to set a new standard for high-rise office structures.
Since August of 2004, this massive project has been pushing skyward toward a scheduled 2008 completion date. When finished, the 55-story office building will offer 2.1 million square feet of office space, primarily occupied by Bank of America, the building’s major tenant and partial owner. One Bryant Park will reach a height of 945 feet—1,200 feet to its spire—and will stand as one of the tallest buildings in Manhattan, second only to the Empire State Building.
When passing by this mammoth structure, onlookers will witness a giant quartz crystal protruding from the city block. Inspired by New York’s famed Crystal Palace, the first light-metal frame building in the United States constructed in Bryant Park in 1853, One Bryant Park features a faceted shape and a clear glass curtain wall to achieve the quartz-like façade.
With a unique architectural vision and specific owner desires in mind, structural engineers at New York’s Severud Associates Consulting Engineers, P.C., faced daunting challenges. From preserving the landmark theater on the intended site to designing a steel-frame building with a concrete core to dealing with sloping columns and varying floor plates, challenges were overcome to create an inspiring design that taught numerous lessons, which can be applied to skyscraper design in the 21st century.
Henry Miller’s Theater
In addition to its office space, One Bryant Park will house the restored and reconstructed Henry Miller’s Theater, a New York attraction since 1918. Because the façade of the original theater has landmark status and cannot be demolished or relocated, the existing brick and terra cotta façade is being restored and a new first-class Broadway theater is being rebuilt behind it. Yet maintaining the original structure’s façade posed some of the most challenging design issues of the project.
“With an existing façade that cannot be altered in any way, the new theater is limited by the façade’s height and width,” explains Edward DePaola, P.E., a principal of Severud Associates and principal-in-charge of the project. “Because the new theater will be larger than the original and will be designed to a more advanced level of service with higher ceilings and wider corridors, vertical and horizontal clearances are further restricted. As a result, the space available for structure is even smaller than usual. This is particularly true for the walls of the auditorium and the transfer of building columns over it.”
For improved acoustics, the theater auditorium is framed as an independent structure with an acoustic joint at its perimeter and ceiling, including the fly tower. In the north-south direction, the auditorium structure has independent braced frames to resist lateral loads. In the east-west direction, however, there was no place to conceal braced frames; moment-resisting frames would not have sufficient stiffness. Instead, bearing pads were located strategically within the acoustic joint to transfer lateral loads from the theater to the building’s lateral force resisting system. Because it is nested within the podium structure, the theater auditorium is not exposed to wind load. Only seismic load will activate this lateral-load transfer mechanism.
To create the necessary column-free space for the Henry Miller’s Theater auditorium, six building columns are transferred at the third floor of the podium. Here, the distinctive geometry of a Broadway Theater became an advantage.
“The walls of the fly tower, located over the stage and extending one floor higher than the rest of the theater, provided a convenient location for a pair of transfer trusses that span the width of the fly tower,” says Severud’s Associate Principal Andrew Mueller-Lust, P.E., who is project executive. “A similar one-floor-high projection for the lounge at the front of the theater hides another pair of trusses. Between each pair of trusses, plate girders span the width of the theater auditorium to transfer the building columns to achieve an 80-foot by 80-foot clear space.”
Henry Miller’s Theater is located on 43rd Street in the northeastern corner of the One Bryant Park podium. When complete, the new auditorium will feature more than 900 seats, a larger lobby, and a restaurant and lounge.
As engineers were addressing challenges with preserving the Henry Miller’s Theater façade, they also were tackling obstacles with the structure’s foundation. To keep the theater from projecting above the landmarked façade, the balcony is located at street level and the orchestra is located below grade. To accommodate back-of-house spaces, such as dressing rooms, as well as building utilities, which include thermal storage rooms, engineers had to design the deepest foundation in midtown Manhattan. With a water table at approximately 15 feet below street level, the perimeter walls are exposed to hydrostatic pressures for most of their height. Therefore, the 60-foot-deep foundation walls are deeply socketed into the rock both to transfer the large lateral reactions and to cut off groundwater. An under-slab drainage system will capture any water that infiltrates the building.
At the eastern third of the building (where the tower core is located), lateral earth pressure is resisted by diaphragm action either cross-lot in compression, or transversely in bending, to perpendicular perimeter walls. At the middle third of the site, large mechanical spaces with varying floor-to-floor heights interrupt the continuity of the floor diaphragms, while at the western third of the site, the acoustic separation of the Henry Miller’s Theater auditorium made cross-lot bracing impossible.
“In both cases, the remaining diaphragm depths were not sufficient to span horizontally around the discontinuities,” DePaola says. “Instead, vertical-braced frames were added to resist the high lateral loads. At the ground-floor level of each frame, the exterior column was transferred to the foundation wall. The additional dead load helped resist uplift and made rock anchors unnecessary.”
As an added complication, the foundation includes a pedestrian passageway beneath the sidewalk on 42nd Street. A reinforced concrete box structure, the passageway will connect the existing New York City Transit Subway entrance at Sixth Avenue (which will also be renovated as part of the project) to the existing sidewalk vault at 4 Times Square. In the near future, the passageway will be extended through 4 Times Square to the Shuttle platforms to create a protected pedestrian transfer between the Sixth Avenue and Broadway subway lines. Plans also include the construction of a mid-block subway entrance.
Form and design
One Bryant Park is essentially a steel-framed building with reinforced concrete shearwalls at the core. The reinforced-concrete shear walls encase the steel frame of the vertical transportation core to resist lateral loads. This unique combination of a steel frame with a concrete core was specified to meet owner desires for hardened elevator shafts and stairways. The project required that the concrete core be constructed after the steel frame was erected, which provided a plumb frame for the concrete pours. To accommodate the self-climbing form system used, ring beams were located around the core, leaving a temporary gap through which the forms were raised.
The floors are concrete fill on composite metal deck, supported by composite steel beams with a clear span of 40 feet. The typical office floor is basically rectangular, but at the northeast and southwest corners, cantilevered projections provide an additional 15 feet of floor space.
In addition to the three cellar levels, the building stack includes an eight-story podium that covers the entire site and an office tower of 43 additional floors at the east end of the site, set back from the podium portion. The highest occupied floor is the 51st floor; above that are four mechanical floors and a roof, but only on the southern half of the building. On the northern half of the building, the 52nd floor roof provides a platform for cooling towers and other mechanical equipment.
For architectural and mechanical reasons (which includes a 9-foot, 6-inch floor-to-ceiling requirement and under-floor air circulation), the typical floor-to-floor height is 14 feet, 6 inches, significantly higher than most office buildings. As a result, the building has fewer floors than might be expected for a building of this height.
A series of sloping surfaces beginning at the 18th floor is critical to achieving the building’s unique faceted shape. Extending to the top of the curtain wall, the four corners of the building begin to slope inward, toward the core, at shallow angles of approximately seven degrees, on average. Each corner starts its slope at a different floor, and each sloping surface is skewed at a different angle—approximately 20 degrees, on average.
A structural design to support the building’s crystalline form proved to be no easy task. To accommodate the sloping surfaces of the façade, the exterior columns, spaced at 20 feet-on-center, are also sloped. “Each column begins sloping at a different floor, and nearly every column at the top of the building is sloped,” Mueller-Lust explains.
At the southeast corner of the building, the lower 10 floors of the façade are recessed to provide architectural emphasis to the main entrance lobby and to orient the building toward Bryant Park diagonally across the intersection of 42nd Street and Sixth Avenue. Here again, sloped columns make the transfer, although this time outward. To delineate the top of the lobby, the columns slope out 3 feet, 6 inches between the third and fourth floors and again between the 11th and 12th floors for an additional 2 feet, 6 inches.
As with the sloped columns higher up the building, transfer girders were investigated but rejected because of depth restrictions. The sloping columns, on the other hand, elegantly negotiate the building line offsets without any increase in the depth of floor framing. However, they do introduce another complication.
“Because up to eight columns offset at the same floor, a significant lateral load (the horizontal component of the column loads) is imparted to the structural system,” DePaola says. “Horizontal trusses were added to the floor framing to transfer the lateral loads to the core and the shear wall reinforcement was increased to account for the local increase in shear.”
The sloping walls of One Bryant Park extend well above the roof levels to conceal the cooling towers, façade maintenance rigs, and other mechanical equipment. Due to the inward slope of the walls, the roof areas are relatively small and provide only enough space for the mechanical equipment. Therefore, the obstruction of cross-building bracing and the depth of traditional ring trusses could not be accommodated. Instead, cantilevered trusses located over each exterior column support the walls.
Faced with many challenges, design engineers credit good collaboration as the key to project success. Members of the design team, including the architects and structural and mechanical engineers, worked closely together at every step of the way. “This project was a perfect example of all team members working together to help meet each other’s needs,” says DePaola. The inspiring One Bryant Park also will provide a perfect example of a skyscraper for the 21st century.
Ashley Kizzire, editorial manager for Constructive Communication, Inc., writes articles for the architecture, engineering, and construction industries. Based in Birmingham, Ala., she can be reached at email@example.com.
Photo credit for above images: dbox for Cook+Fox Architects LLP
Design and construction management team
Project name: One Bryant Park (will also be known as Bank of America Tower), New York
Owner/developer: The Durst Organization, New York
Owner/primary tenant: Bank of America, Charlotte, N.C.
Structural engineer: Severud Associates, New York
Design architect: Cook+ Fox Architects, New York
Executive architect: Adamson Associates, New York
Tenant architect: Gensler, New York
Mechanical engineer: Jaros Baum & Bolles, New York
Geotechnical engineer: Mueser Rutledge Consulting Engineers, New York
Construction manager: Tishman Construction Corporation of New York, New York
Tenant project management: Jones Lang LaSalle, New York
LEED/GBTC consultant: E4 Inc., New York
Energy analysis/LEED/GBTC consultant: Steven Winter Associates, Norwalk, Conn.
Security consultants: Ducibella Venter & Santore, North Haven, Conn.
Code consultant: JAM Consultants, New York
Vertical transportation consultant: Van Deusen & Associates, Livingston, N.J.
Exterior wall consultant: Israel Berger & Associates, Inc., New York
Acoustician: Shen Milsom & Wilke, Inc., New York
Tenant acoustician: Cerami, New York
Exterior maintenance: Entek Engineering Consultant, New York
NYC transit consultant: Vollmer Associates, LLP, New York
Lighting consultant: Cline Bettridge Bernstein Lighting Design Inc., New York
Historic consultant: Higgins & Quasebarth, New York
Theater consultant: Fisher Dachs Associates, New York
Theater acoustician: Jaffe Holden Acoustics, Inc., Norwalk, Conn.
Project team interviews
By Kimberly Kayler and Ashley Kizzire
The design architect
Interview with Robert F. Fox, Jr., of Cook+Fox Architects LLP
Q: What is the greatest design challenge of this project?
A: Ken Lewis, chairman of the Bank of America, asked us to create an icon that would encompass the vision of the bank. In order to answer this challenge, we needed to design a building that would clearly stand as a symbol of the bank, while also meeting our goals of constructing the most sustainable building possible. We wanted to make it apparent through the architecture itself that this is a different kind of building; one that has a fundamentally different regard for future generations.
Q: How does this project differ from other projects of this size?
A: Because it is a project for the Bank of America, the infrastructure was far more complex than in a typical building, even one of this scale. The main tenant will have trading floors and a data center in the building, so the infrastructure back-up and security requirements were far more stringent than usual. Also, working in such a central Midtown location, one of the densest locations in the world, in a post-9/11 environment, posed additional challenges in terms of construction and logistics.
Q: What technology will make this project a success from your perspective?
A: Onsite power, in the form of a nominal, five megawatt co-generation plant, is a tremendously important achievement. This clean, efficient power source will work in concert with the ice storage system and represents the single most important piece of technology in the building. At the same time, the human mind has been just as important—it has taken great dedication on the part of many consultants to fully understand the impacts of every proposed system.
The executive architect
Interview with Partner-in-Charge David Jansen of Adamson Associates
Q: What is the most unique aspect of this project from your perspective?
A: The most unique aspect of this project is the myriad of agendas housed within a sustainable envelope. Obviously many structures are complex, but One Bryant Park required a synergistic, integrated, environmentally sensitive, sustainable, interactive design approach to house and serve many functions, including the critical trading operations of Bank of America. All of the diverse purposes and communities housed within this one sculptural form—an iconic symbol—and these intricate details require intense and extensive design resolution.
Q: What was the greatest design challenge of this project?
A: What makes this project truly unique from a design standpoint is that it is a high-profile urban structure that is not a single-purpose building. While buildings of this magnitude in yesteryear were typically single-purpose structures, such as an office building that would sit empty at night and was used for a mere 2,000 hours per year, this project breaks new ground. In addition to the banking operations, the structure will be home to restaurants, an urban garden, theater—and through a block passageway—retail, a fitness center, and much more. The team designed it from onset to maximize full use of the building.
Q: Did the design team leverage any technology for project collaboration?
A: The sculptural form of the building required the use of extensive 3-D modeling. For example, all of the extrusions have to follow the shape of the building; there are a lot of trapezoidal and parallelogram sections and we had to find a means to solve these complex geometries.
The structural engineer
Interview with Principal Edward DePaola, P.E. (left), and Associate Principal Andrew Mueller-Lust, P.E., both of Severud Associates, Consulting Engineers, P.C.
Q: What was the greatest engineering challenge of this project?
A: The biggest challenge of this project was that there wasn’t just one challenge. In fact, nothing on this project was easy. The gravity loadings were very complex because there were so many building uses. The project includes a very deep foundation—the deepest excavation in the center of Manhattan—to accommodate the Henry Miller’s Theater. The theater itself was hugely challenging, due to its existing landmarked façade that had to be maintained and the tight space restrictions. Adding to this project’s complexity is that almost all of the columns slope and no two floors are the same. Plus, the method of the building’s construction, where the steel frame is erected prior to the concrete core walls, is itself complex: the framing had to be designed to accommodate the self-climbing form system.
Q: What are some of the successes that your team accomplished that you feel most proud of?
A: Even though this is one of the most complex projects we have worked on, it was coordinated the old-fashioned way with good communication and good collaboration. It was a project where the architect, structural engineer, and mechanical engineer worked closely together at every step. Each of us worked hard to help each other.
Q: What is the most unique aspect of this project from your perspective?
A: We considered the way in which the building would be constructed during the design phase. We knew in advance that the steel erection would precede the concrete core, so we designed the framing in the core as a temporary structure. We knew the concrete contractors would be utilizing a self-climbing form work, and our structural design made accommodations for this.
The mechanical engineer
Interview with Partner Scott E. Frank, P.E., of Jaros Baum & Bolles
Q: What impacted the mechanical design for this complicated structure?
A: As the first Platinum-rated LEED high-rise office building in the country, the mechanical systems play an important role in the success of this project and several innovative technologies and systems were integrated into the building. For example, an advanced-design, 5-megawatt, low-emission, co-generation system was selected. In addition, the design team selected a comprehensive gray-water recycling system for the building that collects and stores rainwater, recycles wastewater, collects cooling coil and district steam condensate, and then recycles this water for use by the cooling tower and for flushing toilets.
Q: What hurdles did your team overcome that you did not anticipate having to face?
A: One of the key challenges was the necessity of designing a “building within a building.” The Bank of America occupancy required state-of-the art technology and infrastructure. From the project’s onset we all recognized that this would require extensive coordination and collaboration, but I don’t think you can accurately appreciate the difficulty of integrating all of these complicated systems into an already challenging and complex design.
Q: What impact do you think this facility will have on the community?
A: While this building offers many “firsts” and will be an architectural and engineering icon, the project also will be cited as something to replicate. I believe the One Bryant Park project will set a new standard for New York City, as well as around the globe, for sustainable, high-rise commercial building design.
The construction manager
Interview with Senior Vice President David Horowitz of Tishman Construction Corporation of New York
Q: Describe the complexity of the project in terms of size and volume.
A: This project is impressive just from the sheer numbers:
• approximately 25,000 tons of structural steel
• eight fabricators were contracted in order to meet the steel erection schedule
• almost 60 individual trade contractors are involved in the project
• almost 800 workers will be onsite for the base building,
• more than 1,000 people will be onsite concurrently, for the tenant work
• approximately 68,000 cubic yards of concrete for the superstructure and approximately 18,100 cubic yards for the foundation
• nearly 6,500 tons of concrete reinforcing in the tower, plus 2 million square feet of welded wire fabric
Q: Are there any construction technologies or techniques that can be credited with project success from your perspective?
A: This project was designed as a structural steel building with a concrete core that envelopes the erection steel core columns. The use of the core shear wall forming system from ULMA Form Works, Inc., is certainly unique and a catalyst for project success. We have taken the system to the next level by incorporating additional safety devices into the form system and increased flexibility for faster cycle times.
Q: What impact do you think this facility will have on the community?
A: From an architectural standpoint, the project is extremely unique and will serve as an icon. But, beyond unique architectural appeal, the environmental aspects of this project are noteworthy. The owner and design team simply sought better ways to do things—a better way to ship, store, as well as manufacture the building components. This quest will result in a better structure for the community at-large, as well as the occupants.
Steel frame, concrete core
By Ashley Kizzire
One unique aspect of One Bryant Park’s design is its steel frame and concrete core.What makes this structure unique is that the steel frame is erected first and then followed by the concrete encasement. This system was developed by Severud Associates in the late 1960s and early 1970s, but did not achieve widespread use, mainly due to issues with coordinating the two trades and the lack of efficient forming systems. However, as building owners have begun to desire hardened elevator shafts and stairways and as forming technology advances, this construction methodology is becoming more attractive. The system maintains the speed of erection of all-steel buildings, while leveraging the advantages of the stiffness of concrete shear walls.
This technique presents its own set of design challenges. As placement of the concrete walls progresses upwards, the formwork must also move up, a potentially time-consuming and expensive operation. Traditionally, this might have been done manually with hand-built forms. To streamline the process, however, a self-climbing formwork apparatus, manufactured by ULMA Form Works of Hawthorne, N.J., is being employed.
Furthermore, as each elevator bank terminates, steel columns and beams frame the structural bay. For the lower two elevator banks, this transition from steel framing to concrete presented a difficult gravity load transfer. To minimize steel tonnage, the columns that are encased in concrete are designed only to support the dead weight and construction live load of the steel frame that can be erected before the concrete is placed, a maximum of 12 floors. Consequently, the columns are relatively light W12 sections. This resulted in two design challenges: transferring loads from the steel columns to the concrete walls and controlling the potential for differential elastic shortening.
Where the first two elevator banks terminate, at the 22nd and 32nd floors respectively, the service dead and live loads result in columns that are heavy W14 sections. Simply bearing on the wall below was not possible since the necessary base plate would have been too large. Bearing on the W12 column below would not work either, since there would be insufficient area for a steel-to-steel transfer and too many studs would have been needed to transfer the load from the steel to the concrete. Instead, two trusses will be encased in the top two floors of the core walls to spread the load over an approximately 20-foot-width of wall in two directions.
Toward the top of the building, where the concrete portion of the core diminishes, moment-resisting frames at the building perimeter take a larger share of the lateral load. For the mechanical levels above the 54th floor, where the concrete core terminates, braced frames (not possible at office floors due to obstruction of the view) carry most of the wind and seismic loads.
Because of the advantages of this distinctive design, a steel frame/concrete core structure can provide advantages to similar high-rise construction projects. This type of construction provides the best of both worlds—the speed of steel and the strength of concrete. Plus, when the concrete is poured after the steel is erected, the concrete meets a plumb surface. For these reasons, this process may become increasingly more common in the future.
Photo credit: Bernstein Associates Photographers, Courtesy of Tishman Construction Corporation of New York
Worlds ‘greenest’ high-rise building
By Ashley Kizzire
Marking a change in the very way high-rise buildings are conceived, One Bryant Parkis the first high-rise project to strive for U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) Platinum designation. By reaching this goal, One Bryant Park will become the world’s most environmentally responsible high-rise office complex. One Bryant Park will incorporate innovative, high-performance environmental technologies to promote the health and productivity of tenants, reduce waste, and ensure environmental sustainability.
In working toward a LEED Platinum designation, One Bryant Park has lofty environmental goals: reducing energy consumption by 50 percent, reducing potable water consumption by 50 percent, ensuring zero stormwater contribution to the city’s wastewater system, utilizing a minimum of 50 percent of recycled materials in the building’s construction, and obtaining a minimum of 50 percent of the building materials within 500 miles of the site.
Many mechanical systems and architectural features will help achieve the project’s environmental goals, but the structure will aid these achievements as well. Structural steel has a very high content of recycled material, and most of it will be procured within the 500-mile radius considered local to the site. Concrete, also typically a locally produced material, will have a high recycled-material content with the substitution of blast furnace slag for 45 percent of the cement. Blast furnace slag is a waste product of the steel smelting process and results from the chemical interaction of lime and non-metallic minerals in iron ore. Not only will recycling the blast furnace slag into the concrete mix help to reduce the amount of new material needed, but it also will make the concrete stronger, denser, and more durable than concrete containing only cement.
In addition to its sustainable structural elements, the building is set to have groundbreaking environmental features, including a gray-water recycling system, energy conservation and internal production capabilities (generating 70 percent of its energy), and air purifiers.
The tower’s gray-water system captures and reuses all rainwater and some wastewater, translating to a savings of 10.3 million gallons of water each year. Water conservation is also achieved through waterless urinals and low-flow fixtures and faucets.
The building’s design will provide dramatic reductions in energy consumption. Translucent floor-to-ceiling insulating glass contains heat and maximizes natural light, and LED lights automatically dim during the daytime. The southwest corner of the building dissipates the sun’s heat. A state-of-the-art, 5.1-megawatt, combined cycle co-generation plant located on site provides clean, efficient power.
To provide safe and high-quality air inside the building, carbon dioxide monitors automatically adjust the fresh air supply. The building’s air filtration removes 95 percent of particulates, plus ozone and volatile organic compounds. Not only will air entering the building be purified, but it will be cleaner when exhausted, thereby making the tower a type of giant air filter for Midtown Manhattan.
The New York-based firms of The Durst Organization, project developer; Cook + Fox, architect; Tishman Construction, construction manager; as well as Bank of America, have a notable commitment to environmentally responsible buildings. And when these firms complete One Bryant Park, a new and much greener standard for high-rise buildings will be set.
Photo credit: Doyle Partners for Cook+Fox Architects LLP