STEEL SOLVES MIXED-USE CHALLENGES AT NEW YORK UNIVERSITY DORMITORY
Dorm life at New York University (NYU) is anything but dull these days following the recent completion of the new Palladium Residence Hall. An Olympic sized 2S-meter swimming pool, rooftop dining area, two regulation basketball courts, a gymnasium, a climbing wall and an aerobic fitness room, are just a few of the facilities and amenities designed to keep studentsa happy and healthy on the university’s Washington Square campus.
Built on the site ofthe Old Palladium Theatre on East 14th Street, the 167-ft.-tall mixed-use residence hall accommodates up to 1,000 students and faculty in apartment-style housing units on 12 upper floors. General purpose and study lounges, a game room and music practice rooms are also located on the uooer floors
The 65,000-sq.-ft. sports center is located on two basement levels with two stories of retail startingat street level. Located on the third floor are student life facilities such as a librarv, music room, lecture halls, food court and the outdoor dining pavilion.
The residence hall is one of the most recently completed elements of NYU’s 25-year-long, billiondollar building and renovation program to upgrade and expand its historical campus setting.
HOST OF CHALLENGES
The multiple functions of the residence hall created a series of design and technical challenges for Thornton-Tomasetti Engineers, the structural engineer for the project. The different physical requirements for the facility’s varied uses, combined with zoning height and building setback constraints, called for innovative thinking to adapt the tight site to the different functions.
On the residential floors, the need to accommodate the target number of beds within buildingheight restrictions limited floor-to-floor heights to 8 ft. 8 in. The engineers selected reinforced concreteconstruction from among other alternatives, using 7 in.-thick flat plate floor slabs and a maximumcolumn spacing of 21 ft. on center. But the closely spaced columns of the residential floors were not suitable for the retail space below and, to add to the complexity, theswimming pool and basketball courts in the sports center below groundrequired an even greater amount of column-free space, including spansof up to 100 ft.
To create the open space needed in the retail and recreational areaswhere continuous use of deep girders was not suitable, the engineersneeded the long-span capabilities of steel framing in the entire lowerDortion of the structure
To accommodate the different column layouts for each of the building functions, more than 100 column transfers were required, with transfers occurring at the 13th floor, where the building’s geometry changes considerably, and at the sixth and fourth floors. However, the majority of the column pick-ups take place at the third floor, where the building switches from residential to retail use and the structural steel framing begins.
Achieving the column-free space necessary for the retail operations on the first two stories required transferring the loads carried by the closely spaced columns of the residential and student activity floors above. The third floor was therefore desionated the transfer floor for the transition from concrete to steel.
Additional load transfers occur below the third floor to accommodatelocal variations in layout. A lofty, three-story-high lobby was createdfor the main entrance on the ground floor by transferring four interiorcolumns on the fourth floor using a 40-in.-deep steel transfer girder.Other column transfers were needed at this level to allow for clearanceswithin the dining facilities and other areas designed for circulation.
Column-Free Space Required Posing another structurat chat, lenge was the need for a 100-ft. x 100-ft. column-free space above the swimming pool. A two-story-high, 10o-ft.-long steel truss was designedto run west to east from the first basement level, where the swimming pool is located, tothe second floor, bisecting the 100-ft. space. However, it was architecturally undesirable to place a truss at the eastern perimeter of the space to pick up the columns from the floors above, since the conventional diagonal bracing of the truss would obstruct the view from balconies overlooking the pool. lt was also undesirable to place a truss at the western perimeter, although the loads of virtually the entire western building face where it changes shape at the fourth floor had to be picked up as well.
To address this issue, the engineers chose to employ a two-story-high,steel-tied arch running north to south and spanning nearly 100 ft. tosupport the east end of the truss and pick up the loads from the westernfagade. This east-westruss frames into the arch at the second floor andat its horizontal member on the first basement level. A second, shortersteel truss only one-story high was placed parallel to the arch to accommodate the change in building function at the second floor and to betterdistribute the loads from the eastern faqade above it. This combinationof structural elements effectively picked up the loads while generatingthe column-free space required for the pool area and allowing for unobstructed sightlines from the spectator balconies
The $140-million, 400,000-sq.-ft. project has proven a great success.By taking advantage of the benefits of steel, the creative structural solutions ensured that NYU was able to comply with all city zoning standardsand at the same time create a state-of-the-art facility that would be theenvy of college students from all over the world, a place where even themost cynical student would yearn to live.