Base Building Design Challenges
The goal of the 505 Fifth Avenue project was to build a new, "transparent" office building utilizing the latest concrete construction technology. Comprised of three building lots, the 31-story boutique office tower contains prime office space and retail at-grade. The site parameters dictated a side-loaded core set to the northeast corner of the building’s floor plan. The building structure is cast-in-place reinforced concrete with "hardened" cores that provide a level of building safety exceeding New York City building code requirements. One of the project's greatest challenges was designing the curtainwall to accommodate both the inter-story live-load deflection at the cantilever and the inherent shrinkage of concrete structures. The amount of combined live-load deflection, shrinkage and movement due to building sway, was just less than one inch. The design team accounted for potential movement in the cladding system while maintaining an elegant visual aesthetic both inside and out, and a weather-tight enclosure.
Shoring & Bracing Requirements
505 Fifth Avenue's property line is located within 20ft of a subway tunnel, which created a unique challenge for the project team and the MTA. The approved shoring/bracing submission to the MTA called for “rackers” and “dead men” along a 100ft length of the perimeter foundation wall. The approved design would affect the foundation schedule by approximately eight weeks. In order to lessen the impact on the schedule, our field staff worked side-by-side with the successful bidder to establish an alternate method of shoring/bracing that lessened the eight-week impact by six weeks once the excavation/foundation procurement process was completed. The team's solution consisted of a series of 4’x4’ concrete piers approximately 30ft in depth, with rock anchors and intermediate plank sheeting. The MTA permitted our firm to proceed and the excavation/foundation scope commenced without interruption.
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