Excellence In Structural Engineering Awards – Outstanding Project
Fishers Island Residence – Fishers Island, NY
Structural engineer : Skidmore, Owings, and Merrill, LLP
In an effort to create this uninterrupted connection, the architect used high-performance, insulated floor-to-ceiling glazing on all four external walls of the house. To minimize visual interruption in the glazing, the structural engineer designed slender 2.75-in. square, solid steel columns supporting W10 primary beams that span 29 ft and W4, L3x3 and L5x5 secondary steel beams. The wide-flange steel roof framing supports a 1.5-in. wide, rib metal roof deck. Steel framing was essential for maintaining uninterrupted windows and allowing shallow roof spans.
The design of the Fishers Island Residence is a response to the unique island setting and the personal interests of the client and primary resident.
“A very simple design that lends itself very well to its surroundings,” commented Brad Lange, pre-construction manager, The Weitz Company, Des Moines, Iowa, and a judge in the competition. “They did a nice job of using exposed structural steel to add an artistic flair.”
The structural elements were carefully coordinated with the architectural expression, which greatly understates their relationship: the structural steel elements are the architecture. The exposed structural steel columns were engineered to be as small as structurally possible and designed to maintain a consistent, clean aesthetic throughout the house.
The aesthetic treatment of structural steel is prominently displayed by the 50 steel “trees” every 11-ft, 6-in. around the house. Each tree consists of a solid 3.25 by 3.25 in. steel cantilevered column, rigidly fixed at the base. A steel casting at the top of the column is connected with a single, concealed, high-strength bolt. The casting spreads into four diagonal cast “branch arms” at the top of each column that cantilever out approximately 8 ft from the columns.
A trellis of solid aluminum rods is supported at the tips of each branch arm. A secondary system of trellis framing spans above the aluminum rods, cantilevering an additional 3 ft beyond the edge of the branch arms. The secondary system is supported by individual, high-strength rods attached to an innovative concealed “tongue plate” connection detail. The concealed tongue plate and rod connection allows the trellis to float above the branch arms with almost no visible means of support. An adjustable and fully concealed steel puck-like connection at the base of each support rod permits adjustment of the trellis-to-branch arm connections.
The trellis, steel trees, and branch arms are visually dramatic but also are essential to making the residence habitable. The canopies and trellis shield the full-height glass walls from direct overhead sunlight, dramatically reducing glare and light levels within the house. The steel trees also play an important role in the psychological transitioning between the outdoor natural realm, and the man-made environment of the interior.
To provide the unique architecture of this residence, the architect and engineer worked closely to develop connections that were structurally robust and visually pleasing, avoiding conventional structural steel connections that would have ruined the visual experience. The use of architecturally exposed steel castings celebrates steel connections as sculptural objects, but required intense coordination among the architect, engineer and fabricator. All steel elements were designed per code to resist the harsh 120 mph coastal winds and significant ice and snow loads.
Project team members include architect Thomas Phifer & Partners, New York; structural engineer and AISC member Skidmore, Owings & Merrill, LLP, Chicago; general contractor BD Remodeling & Restoration, Fishers Island, N.Y.