The Judges in the 2016 Engineering Excellence Awards Competition have selected 150 Charles Street for a 2016 ACEC New York Gold Award in the category of Structural Systems.
This 300,000 square-foot, 16-story luxury residential development in Manhattan’s West Village consists of 98 condominium units. The project incorporates the façade structure of an existing 4-story warehouse for the lower podium floors. Above, two corner towers flank a mid-block volume and each floor steps back, forming a cascade of terraces toward the Hudson River. The superstructure accommodates high gravity loads due to precast façade assemblies as well as 40,000 square feet of landscaped courtyards, green-roofs and planted terraces with up to five feet of soil cover. The building’s total landscaped area is equivalent to the combined areas of four small neighboring parks.
The building foundations are located 2 levels (30’) below grade and consist of a 3-foot mat, with 2 zones of 44” at shear walls. The building sits on uncontrolled fill consists of sand, silt and demolition debris such as rock rubble, brick fragments, cinders, slag and wood. Tie down anchors prevent hydrostatic uplift. These foundations support high gravity loads, including a substantial amount of above-grade landscaping of varying topography, whereby some areas have 24” of soil, others 18” or 6”, and elsewhere there are only pavers.
Another source of high gravity loads was the façade system. In addition to pre-fabricated panel components (in this case pre-cast concrete with brick exterior), the building features a variety of façade systems including, masonry cavity walls, curtain walls, window walls, stone cladding & storefront assemblies. Having both structural and building envelope teams in-house allowed communication of structural requirements internally, without the need for time-consuming Request for Information processes through the architect, thus enabling speedy communication and coordination of interacting structural and envelope systems.
150 Charles Street has over 300 columns, though few of these extend the full height of the building. Columns are transferred from level to level, because each floor has a distinct architectural layout. The 41 various column sizes employ 250 transfers, whereby columns substantially changed location, size/shape, or orientation between floors. In-slab transfers range in thicknesses between 18” to 22”. Designating a single uniform thickness was not possible due to architectural layouts and required clearance for mechanical systems.
Due to the great variety of column shapes/sizes/orientations, slab thicknesses, and transfer areas, many different types of Studrails of varying stud-spacing and diameter were required. In order to better facilitate the installation process, the Studrails were itemized not only on shop drawings, but also on a color-coded markup that corresponded to colors sprayed onto the Studrails themselves during fabrication. This enabled the lathers to quickly identify which rail they see and where it’s to be placed. This method also assisted the inspection process, checking that placement conformed to the design.
The structural engineer’s continuous presence in the field allowed for quick responses to coordination issues. Since Structural Engineer also served as special inspector of concrete and steel, the engineer-inspector was on-site as work was being conducted. The contractors would assign one or two journeymen to be guided by the engineer-inspector, and respond to unforeseen field conditions, maintain the workflow, and allow subsequent trades proceed.