Because of the redistributed roof load, only the end diagonal built-up members required welded steel plate reinforcing. The original truss-bearing plates were not large enough to distribute the increased load to the masonry bearing walls. New grillage beams that bear on top of the masonry wall were added above the 8th floor. The truss ends were connected to the beams by welding added plates, effectively hanging the truss from the grillage beam.
New large ensemble space within the South Tower. Photo credit: Jeff Goldberg/Esto.
- New large ensemble space within the South Tower. Photo credit: Jeff Goldberg/Esto.
Carnegie Hall is a National Historic Landmark and one of New York City’s most famous concert venues. The three buildings comprising Carnegie Hall, all constructed in the 1890s, are the 6-story original building that contains the Isaac Stern auditorium, the 12-story South Tower, and the 14-story North Tower. The structural system in the original building consists of unreinforced masonry bearing walls and cast-iron columns that support steel beams and trusses. Both towers were constructed with steel-framed columns and beams.
The complex renovation of non-performance spaces within both towers created a world-class environment for the institution’s music education programs; a new 61,000 sf education wing now extends across the upper levels of the towers. The project also refurbished the concert hall’s backstage areas and upgraded archives within the education wing. Performances continued uninterrupted while the carefully phased construction was underway. This project is LEED Silver certified.
Photo credit: Jeff Goldberg/Esto.
Main Hall Roof
The roof over Stern Auditorium is supported by seven steel trusses spanning 110 feet. As part of this project, the space between trusses was converted from leased tenant space to administrative offices. A portion of the roof needed to be raised to accommodate an expanded mezzanine area. The roof also needed to support the added weight of saturated soil, trees, pavers, and assembly occupancy of the new roof terrace.
To avoid reinforcing the bottom chord of the truss, which is near the Stern Auditorium ceiling, Silman took advantage of the raised roof and placed a built-up steel girder above the top chord of the truss, which redistributed most of the roof loads to the diagonal members at each end of the truss.
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Roof Trusses
Roof Trusses
Because of the redistributed roof load, only the end diagonal built-up members required welded steel plate reinforcing. The original truss-bearing plates were not large enough to distribute the increased load to the masonry bearing walls. New grillage beams that bear on top of the masonry wall were added above the 8th floor. The truss ends were connected to the beams by welding added plates, effectively hanging the truss from the grillage beam.
Investigation and Monitoring
Original design drawings for Carnegie Hall no longer existed, so Silman conducted extensive field investigations and coordinated materials testing of the historic steel to confirm strength and weldability. All three performance spaces at Carnegie Hall (Stern Auditorium, Weill Recital Hall, and Zankel Hall) contain finishes that are sensitive to excessive vibrations. A vibration monitoring system including seismographs was installed to monitor all three areas and provide real-time alerts of high vibrations so that construction activities could be modified as needed.
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New Rooftop Terrace
This renovation transformed the roof of the main building – above the famous Stern Auditorium and adjacent to the new Education Wing – into a 10,000 sf landscaped outdoor terrace, a concept first envisioned for the building by its original architect. Angled skylights bring natural light into the offices below.
New Rooftop Terrace
This renovation transformed the roof of the main building – above the famous Stern Auditorium and adjacent to the new Education Wing – into a 10,000 sf landscaped outdoor terrace, a concept first envisioned for the building by its original architect. Angled skylights bring natural light into the offices below.
North and South Towers
The existing floor construction of the North Tower did not provide the ideal acoustic mass required for the new ensemble rooms in the top seven floors. There was also the need to preserve existing double height ceilings in some areas and to maximize ceiling heights in other areas. Near the new ensemble rooms, Silman added 7-inch concrete slabs on steel decking supported on new steel beams. In circulation areas where acoustics were less of a concern, a thinner composite steel floor system was used. This, in conjunction with steel beam penetrations, allowed the installation of a new central air conditioning system.
The new ensemble room at the 10th floor of the South Tower required the removal of significant portions of the 11th floor, three interior columns, and transfer girders to support the columns that remained above the 12th floor. To avoid increased loading and additional reinforcing of the existing structure below, Silman reduced the load of the existing floor assembly by removing cinder fill and replacing it with lighter-weight polystyrene.
