Brought to you with support fromNew York-based architectural practice CetraRuddy is no stranger to designing residential skyscrapers in Manhattan, with a body of work differing from typical contemporary glass stalagmites thanks to the inclusion of significant swathes of stone and metal. ARO, a slender 62-story tower located in Midtown West that wrapped up this year, continues this trend with a facade of undulating and shifting floorplates clad in a skin of aluminum composite panels and enclosed with tinted float glass. The 540,000-square-foot tower rises from the center of the site to further the distance from the adjacent properties to the east and west, a measure taken to maximize the building's allotted zoning height and overall daylight penetration. DeSimone Consulting Engineers handled the tectonics of the project's structural system. "To adequately support the slender building," said the structural team, "the tower's structural system is comprised of steel columns at the foundational level, reinforced concrete shear walls with flat plate concrete floor slabs, and reinforced concrete columns. Overall, construction utilized 34,000 cubic yards of concrete."
Guardian Glass with a remarkably lower heat coefficient than typical coated clear glass, was custom assembled by systems producer BVG Glazing Systems. John Cetra, Founding Principal of CetraRuddy, is co-chairing The Architect's Newspaper's Facades+ NYC conference on April 2 & 3 and will present the ARO in the afternoon panel "Optimizing the Form."The structure is just one of the visibly outward elements of the overall design and the floorplates protrude as a series of undulating ribs from the narrow vertical form. Across the four elevations, the structure is key to the articulation of the six different curtain wall modules with differing ledge depths corresponding to the placement of the glass modules. Eighteen-inch-deep, white Reynobond aluminum composite "fenders" cap the floorplates, soffits, break up the floors as thin rectangular columns, and act as integrated solar devices. "The sun is a friend of this building; the sky is reflected in its glass and the metal fender protects from undesirable solar gain and glare," said CetraRuddy. "The projecting undulation captures the sunlight, giving the facade pleasing depth and visual interest." As a result of the tower's shifting floor plates and undulations, the glass modules shift in their alignment from being stacked directly atop one another to a quasi-stepped appearance. Each panel is approximately four feet wide and 11 feet tall, and are fastened to the floor plate with steel embeds. The glass, a tinted float glass produced by
Brought to you with support fromModular construction is gaining steam in New York City, with the technique being utilized for new projects ranging from affordable housing to academic facilities. In September 2018, modular technology reached a new height with the tallest modular hotel in the United States, the 21-story citizenM New York Bowery located in Manhattan. For the modular units, Concrete Architectural Associates, Stephen B. Jacobs Group Architects and Planners, and DeSimone Consulting Engineers reached out to Polish manufacturers Polcom Modular, and Aluprof S.A. The units, which measure 48 feet by 8 feet by 9 feet and incorporate two hotel rooms and a central corridor (following a pattern of guestroom-corridor-guestroom), were specifically designed to navigate the street width of New York City. Each module was assembled with the street-facing facade included.
Red Hook Terminal. From Brooklyn, a convoy of flatbed trucks transported the units across the East River to the construction site. The project began with the construction of a four-story concrete base, topped with a 36-inch-thick slab that spans up to 38 feet. This podium, which houses larger amenity spaces below, serves as a transfer slab to support the modular pods above. While the bulk of the citizenM New York Bowery hotel is composed of modular units, there are certain structural elements that span the building’s height. Prior to the craning in of prefabricated components, the construction team poured a full-height concrete structural core along the sites southwest corner and a sheer wall to the north. These concrete structural elements are the primary lateral system for the tower, with the sheer wall largely preventing the modular units from twisting. "Diagonal strap bracing on the module ceiling acted as the floor diaphragm to transfer the floor lateral loads back to the sheer walls," said DeSimone Consulting Engineers Managing Principal Borys Hayda, "the sheer wall's steel connection plates were bolted into the module ceilings and the female end of a Halfen stud embedded into the concrete structure." Once on site, the modules were lifted by crane and stacked module-to-module, each tied to the one directly below by bolted connections. According to DeSimone Engineers, "countersunk bolts were typically used for the diaphragm connections to prevent boltheads from interfering with the bearing of the module above." During construction, the prefabricated units were effectively cocooned within a watertight membrane, with the central portion later being cut out for the hotel’s corridors. After a brief learning curve at the start of the project, the construction team was capable of installing one floor of modular units per week. The top two floors of the tower are framed by structural steel, allowing for larger amenity spaces.Following fabrication, the 210 modular units were transported hundreds of miles from the manufacturing facilities in Goleszów, Poland to the northern port city of Gdańsk where they began the second leg of their trip to New York’s
High performance facade design is as much a science as an art. Structural engineers can bring crucial knowledge to the architect's drafting table, including how building movement and deflection will impact the building envelope. From the engineer's perspective, collaboration is better when begun sooner rather than later. "We like to be involved in the conceptual phase so we can actually integrate a structural solution into the facade," said Stephen DeSimone, President and Chief Executive of DeSimone Consulting Engineers. "More recently, the expression of structure has become a part of the architectural solution with breathtaking results." DeSimone will deliver a talk on "Determining and Understanding Lateral Loads" at next week's Facades+NYC conference. DeSimone will discuss how innovative engineering can enhance facade performance. Take wind tunnel testing, for instance. "We've been wind tunnel testing 'after the fact' for decades," explained DeSimone. "What we are doing now is letting the results of the wind tunnel inform the shape and orientation of the building. Through shaping we were able to reduce the frame as well as facade loads, resulting in significant cost savings." Only 7 days away, Facades+NYC gives you the opportunity to hear more from DeSimone and many other facade design and fabrication experts.
In South Florida, where hurricane "season" occupies a full six months of the calendar, AEC industry professionals are especially attuned to the challenge of designing for high winds. Vincent J. DeSimone, chairman of DeSimone Consulting Engineers, has been there—and knows just where to look for answers. "The most useful tool that structural engineers have to determine the forces on the building skin is wind tunnel testing and the ensuing results," said DeSimone, who will deliver a talk on "Innovative Facade and Building Design Through Modern Wind Tunnel Engineering" at September's Facades+ Miami conference. During a wind tunnel test, explained DeSimone, engineers place a scale model of a building inside a tunnel, then vary the wind speed and direction to determine the pressures on the structure. Sensors detect these pressures, which are then translated into forces acting on the facade. Forces on the facade vary from low to high, he noted, and some "hot spots" on the building envelope can achieve local forces in excess of 200 pounds per square foot. The load for the structure as a whole are generally determined by average these minimum and maximum forces. Per the applicable building codes, Miami-area structural engineers base the wind forces used in wind tunnel strength tests on maximum wind forces for a 50 year wind cycle. Building movement is another matter, said DeSimone. For architects and builders in Miami, the allowable lateral displacement—the height of the floor divided by 360—is determined using a 25 year wind cycle. In a building with a story height of 12 feet, in other words, the allowable movement is 0.4 inches. "In seismic zones where movement is expected to be much higher during a seismic event, facades are allowed to be much more flexible," observed DeSimone. "Knowing that facades do not determine the allowable movement of a structure, doesn't it stand to reason that here in Miami we are designing buildings much stiffer than they need to be?" Recalculating allowable movement according to a 10 year wind cycle, for instance, could reduce the building's shear walls by 22 percent. "This reduction—which, by the way, is used all over the country—results in a true sustainable reduction in material," he said. "Remember, the most sustainable building is the building you don't build and, conversely, the building which uses the least material." Learn more from DeSimone and other experts in high performance envelope design and fabrication at Facades+ Miami September 10–11.