Achieving Higher Quality in High-Density Residential: the Strengths of Structural Steel

Maximize space, versatility, and quality in mid-rise and high-rise apartments and condominiums
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Long-Span Composite Deck

Composite metal deck economically spans 8 to 10 feet between beams. An effective design solution is to implement long-span deck with structural steel framing to avoid intermediate framing on spans much shorter than a typical apartment or condominium unit. High-strength long-span steel deck is used with concrete cover to create spans of 28 feet and greater. The depth of the floor system is typically 10 to 12 inches for spans up to 35 feet, but can be designed to be slimmer. Shoring is required to support the long span deck at approximately 10-foot intervals while the metal deck replaces formwork for the poured concrete. Long-span composite deck systems may be prefabricated in large bay sizes, allowing for modular methods of construction, which often are of benefit in fast-track construction projects. Unprotected long-span deck achieves 1-hour and 2-hour UL-approved ratings when provided with concrete cover of a specified design thickness. Deck may be left exposed or finished with gypsum board depending on the desired aesthetic. This system, when finished with a gypsum board ceiling, is lighter in weight than a typical all-concrete solution while still meeting necessary performance criteria for sound control, impact isolation, and floor vibration.

In-Wall Beam

It is natural for architecture and structure to require extensive collaboration prior to completion of the design. In apartment and condominium buildings, the room sizes are set on modules that guide, or are governed by, the column spacing of the structure. The long-span capability of structural steel framing allows for the architectural layout to effectively inform the spacing of the structural grid.

In-wall beam framing is a classic example of a system in which the framing is developed to align with the partition layout of the interior. Wide flange beams are designed to span the distances required to reduce intermediate framing in room interiors. The modules of beam-free space allow for higher floor-to-ceiling heights while room partitions enclose the beams that support the floor system. Composite deck as thin as 5¼ inch total thickness is able to achieve a 2-hour rating with unprotected deck, benefitting a low floor-to-floor solution. With an in-wall beam framing system, the program layout and design comes first followed by support from the steel structure.

 

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Originally published in Architectural Record
Originally published in August 2015

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