As part of its $400M commercial tower redevelopment, Midtown’s 660 Fifth Avenue (formally known as 666 Fifth Avenue) has undergone a total modernization that includes removal of numerous interior columns, the addition of new infrastructure and building systems, and replacement of its mid-century exterior aluminum cladding with floor-to-ceiling windows.
Inside the 39-story office building, portions of two existing columns and low ceilings were eliminated to maximize interior expanse and provide double height spaces and interconnected floors. For the column removals between the 1st and 2nd stories, McLaren worked with OCI (Orange County Ironworks) to provide means and methods for sequencing the column jacking and removal as well as design of the necessary rigging support frames for the installation of transfer girders.
Limited access presented a significant challenge to getting the 36 feet long transfer girders into the building during construction without introducing field splices which wanted to be avoided by the client. First, the team engineered a dolly system to safely roll the girders into the building and provide cribbing to not overload the existing archaic slab structure. The next challenge was lifting the girders into place tight to the underside of the existing slab above and snug beside the portions of the existing columns to remain. To resolve this issue, a temporary rigging framing was used to lift the new built-up transfer girders into place at the 2nd floor framing level from the underside. A temporary trolley beam system was used to transfer the built-up girders to their final position.
As part of its push to modernize the commercial tower’s infrastructure and systems, 660 Fifth Avenue included a new Building Maintenance Unit (BMU) atop the roof. McLaren’s construction engineering division provided complex connection design for the BMU framing connections. Non-typical connection design was required to meet high loading requirements, tight tolerances / limitations due to the BMU wheel attachment points, attachment points to the existing structure, as well as thermal expansion requirements.
Heavy coordination was required with the client to create erectable details that limited the need to work close to the edge of the building and also limited impact to the existing structure. The team provided analysis of the existing Level 9 terrace area which was designated to support the Building Maintenance Unit steel on dollies during its shake-out and rigging processes. The existing slab and framing were checked using both elastic flexural and catenary analysis to confirm it could support the weight of the BMU steel in addition to dead and live loads.
The recladding of 660’s stunning new façade in 11×19 ft single-pane glass units, first required the demolition of its original aluminum curtain wall. Working with Turner Construction Group, McLaren developed facade demolition sequence drawings. The DMO Plans incorporated site safety notes and applicable sidewalk shielding schematics.
McLaren provided a full peer review of the proposed construction equipment and temporary structures in accordance with NYC Building Code to ensure that structural components had been installed in conformance with the approved design drawings and manufacturer recommendations, that OSHA standards were met, and that there were no apparent safety concerns. Inspection and review included the proposed temporary construction fence, sidewalk shed, gates, fixed scaffold, hanging scaffold, tower crane, derrick temporary weather walls, rigging plans, and fall protection.