All steel-framed buildings derive basic structural support from a frame composed of horizontal steel beams and vertical steel columns. Structures must also be able to resist lateral forces produced by wind and earthquakes. In some steel frame structures, this lateral resistance is derived from the presence of diagonal braces or masonry or concrete walls. In welded steel moment-frame buildings (WSMF), the ends of the beams are rigidly joined to the columns so that the buildings can resist lateral forces without the assistance of additional braces or walls. However, earthquakes occur, the welded joints that form these connections can fail, and the building loses some of the strength and stiffness it needs to resist these loads. Once the welded joints fail, other types of damage can also occur, including damage to bolted joints and subsequent severing of beams or columns resulting in a localized collapse. Generally, WSMF buildings constructed in the period from 1964-1994 are vulnerable to this damage. This course has been prepared to provide a nontechnical summary of the valuable information contained in four FEMA/SAC publications, an understanding of the risk associated with WSMF buildings, and the practical measures that can be taken to reduce this risk.
Learning Units: 3.0 LU/HSW (3 hours)
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