Serviceability & Resilience
Structural steel is exceptional in addressing building serviceability requirements under both normal and extreme conditions
A structural steel framing system not only satisfies the structural requirements of the building, but also effectively addresses serviceability requirements-that is, its functionality as it relates to occupant comfort and building usability. A building that may still be structurally sound would nevertheless be considered unfit if exhibits excessive vibration or movement. Serviceability refers to conditions other than the building strength that render the buildings unusable.
Any structural steel framing design must consider vibration in order to avoid undesirable movement. Vibration or "bounciness" can affect anything from a worker at her desk feeling the slight sensation of the floor bouncing beneath her (annoying) to a highly sensitive piece of imaging equipment in a radiology wing not being able to properly document a scan (unacceptable). Vibration isn't a function of the structural material, but rather a function of how it is designed. Structural steel is designed according to published standards that factor vibration considerations into the design process. When properly addressed, vibration concerns can be easily overcome.
Horizontal sway is expected with buildings and is in fact relied upon by the structural engineer in some cases. Unlike other framing materials, structural steel behaves in a very predictable way and allows limited movement under common conditions without alarming building occupants. As such, steel systems are often designed to control the amount of sway or drift a building might encounter in its lifetime. Some sway-control systems are even exposed by the designer to enhance the building's elegance.
Serviceability concerns also encompass how a building performs during and after an extreme event. Structural steel provides opportunities for easy repair and/or replacement after an exceptional wind or earthquake event where other materials cannot. Resilience following a blast or terrorist attack is a newer concept that further challenges the engineer's ability to design for drift. Current building codes address occupant safety during an extreme event but not a building's functionality following the event. Structural steel's inherent resilience as a material, coupled with purposeful design decisions addressing resilient requirements, can address the owner's desire to maintain select building functions after an extreme event.
Example projects that illustrate steel's serviceability and resilience benefits:
Living (Comfortably) with Vibration - Vibration due to human activity is a major design consideration. But it doesn't have to be a problem.
Braced for the Future - Architectural vision and high seismic demands culminate in architecturally expressed mega-braces for the most resilient skyscraper on the West Coast.
Facing the Storm - When properly designed, detailed, and constructed, structural steel offers an excellent solution for buildings subjected to high hurricane winds.
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