Los Angeles, California
183,000 gross square feet, 230' tall.
Built-up steel plate band exoskeleton with exposed cementitious fire proofing, wide flange girder floor framing with exposed metal deck at perimeter, steel plate shear walls (SPSW) at core, triple pendulum base isolated structure, aluminum window wall glazing, cement plaster hyperbolic support walls and stair enclosures, cast in place concrete subterranean garage.
Dolan Daggett, Vanessa Jauregui, Diana Rodriguez, Maxime Lefebvre, Renata Galan, Hugo Ventura, Raul Garcia, Emmanuel Osorno, Brennen Huller, Tanveer Sami, Sean Briski, Nicholas Barger, Zarmine Nigohos, Richard Yoo, Scott Nakao, Christine Lawson, Francisco Delgado
AIA/LA NEXT LA Merit Award, 2010
Panoramic Site Photos - John Schwarzell / Axis Images
The original Jefferson Towers project – two 230 foot high-rise towers and parking – was approved by the Los Angeles City Planning Commission and the Los Angeles City Council in 1999. At the time of its original approval the only high rise proposal in the South Central Los Angeles area, the location for two urban riots in the last fifty years. Today the project continues to be the only tower proposal in that section of the city. The project carries with it the aspiration for a renewal of an area which has had more than its share of poverty, and the accompanying social pathologies, in comparison with other more affluent parts of Los Angeles. The only other significant new development project in that neighborhood was the Cineon Kodak air-rights project, completed in 1996 within the original 45 foot height limit, and considered to be the first phase of the re-development of the tower site. The towers are the second phase of that re-development.
The conceptual strategy for the project was a structural strategy, and that strategy remains in the most recent version. A continuous system of curvilinear ribbons, neither beams, nor columns, wraps the two contiguous boxes – T shaped in plan – allowing a completely open, column-free interior. The ribbon language was developed in parallel with the Wexner Museum exhibition, the Dancing Bleachers , at the time that installation was designed and installed.
The towers project was dormant for several years, then resurrected in 2006 as a single tower with parking at grade and below grade. After a complex series of Los Angeles City reviews the project was re-approved and re-designed. A primary impetus for the return of the project was the advent of a surface, passenger rail system, running from downtown to the University of Southern California, south of downtown, then west along Jefferson Boulevard to a stop at Jefferson and La Cienega. That intersection is a primary crossing of major north-south [La Cienega] and east-west [the 10 freeway] traffic axes in Los Angeles. The project site is a block west of the train stop, and sits adjacent to the train route as the train turns north to a second stop, several blocks west of the site. The train makes the tower site readily accessible by surface rail, and that development convinced the owners of the economic viability of the tower building. The project, because of its height and the relatively low buildings that surround the site, will have enormous prominence both as an object on an otherwise 45 foot high skyline, and as an opportunity to provide long distance views in every direction for the office building’s tenants. Both the opportunity to build a free-standing tower with no intervening obstacles to views of the project, and vistas from inside were also persuasive arguments for the revival and re-design of the building.
Both the new tower and the new passenger railway and train stop are likely to become prominent symbols of the rebirth of South Central Los Angeles.
In plan, the new tower keeps the top box of the two contiguous boxes that forms the T shape. The northern length of the remaining box adjoins the railway right-of-way south of the tracks. The intersection of Jefferson and National is re-designed both to facilitate the location of the train tracks, the adjoining streets, and organization of automobile entry from the signaled intersection. The project provides valet service and accessible parking at grade and 2 levels of below grade parking . Pedestrians leaving the train station to the east, walk along the north elevation of the site, then proceed up a stair or elevator to the second floor tower elevator lobby.
The new tower, with floor plates of 15,000 square feet per floor, is supported on a structure of curvilinear steel tube ribbons, one foot by five feet, filled with concrete. The ribbon system is located external to the floors, so the floor interiors are entirely open and flexible. The ribbons are resolved at the base of the tower as a series of intersecting hyperbolic support walls that geometrically join ribbons on one elevation of the bar with ribbons on the opposite side.
Rather than the conventional single floor to floor height, typical of most tower structures, this project offers three alternative floor to floor heights to its tenants, one at 13 feet six inches, one at 16 feet six inches, and one at 24 feet. The 24 foot volume occurs three times, and allows the construction of a glass enclosed, acoustically segregated mezzanine floor, should the tenant require such space.
The tower has an external elevator and service core on the south elevation, and one exit stair case positioned at the east of the floor plans. Shear loads are shared between the rigid frames formed by the intersection of the ribbons, and the two circulation and service cores.
The primary structure for each floor plate is a pair of parallel, steel girders, each 10 feet from the floor perimeter, running lengthwise. The girders are, in turn, supported by 10 foot beams that connect to the ribbons, as they pass each floor line, with the concrete girders to support the floors. Secondarily, Vierendeel trusses span between the girders to support the floor slabs and allow building services to pass in the long direction of each floor.
On the south and west elevations, the most difficult sun control elevations, remaining vertical glazing above 8’, varying in height and depth, depending on the changing floor to floor heights, is canted inwards to protect the elevation from direct sunlight.