Moment-resisting frame is a rectilinear assemblage of beams and columns, with the beams rigidly connected to the columns.
Resistance to lateral forces is provided primarily by
rigid frame In structural engineering, a rigid frame is the load-resisting skeleton constructed with straight or curved members interconnected by mostly rigid connections, which resist movements induced at the joints of members. Its members can take bending mom ...
action – that is, by the development of
bending moment
In solid mechanics, a bending moment is the reaction induced in a structural element when an external force or moment is applied to the element, causing the element to bend. The most common or simplest structural element subjected to bending mo ...
and
shear force in the frame members and joints. By virtue of the rigid beam–column connections, a moment frame cannot displace laterally without bending the beams or columns depending on the geometry of the connection. The bending rigidity and strength of the frame members is therefore the primary source of lateral stiffness and strength for the entire frame.
The
1994 Northridge earthquake
The 1994 Northridge earthquake was a moment 6.7 (), blind thrust earthquake that occurred on January 17, 1994, at 4:30:55 a.m. PST in the San Fernando Valley region of the City of Los Angeles.
The quake had a duration of approximately 1 ...
revealed a common flaw in steel-frame construction — poorly welded moment connections — and building codes were revised to strengthen them.
Early history
Steel moment-resisting frames have been in use for more than one hundred years, dating to the earliest use of structural steel in building construction. Steel building construction with the frame carrying the vertical loads initiated with the
Home Insurance Building
The Home Insurance Building was a skyscraper that stood in Chicago from 1885 to 1931. Originally ten stories and tall, it was designed by William Le Baron Jenney in 1884 and completed the next year. Two floors were added in 1891, bringing its ...
in Chicago, a 10-story structure constructed in 1884 with a height of 138 ft, often credited with being the first skyscraper. This and other tall buildings in Chicago spawned an entire generation of tall buildings, constructed with load bearing steel frames supporting concrete floors and non-load bearing, unreinforced masonry
infill walls at their perimeters. Framing in these early structures typically utilized "H" shapes built up from plates, and "L" and "Z" sections.
[Hamburger, Ron. et al., (2009). ''Seismic Design of Steel Structures''. National Institute of Standards and Technology . NIST GCR 09-917-3.page 3]
References
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Civil engineering
Building engineering