Spotlight on Steel Moment Frames

by W. F. Chen, (M.ASCE), George E. Goodwin Distinguished Professor of Civil Engineering; Purdue University, IN,
E. Yamaguchi, Assoc. Prof.; Dept. of Civ. Engrg., Kyushu Inst. of Technol., Kyushu, Japan,

Serial Information: Civil Engineering—ASCE, 1996, Vol. 66, Issue 3, Pg. 44-46

Document Type: Feature article

Abstract: Engineers' confidence in moment connections was shattered when damage was discovered after the 1994 Northridge earthquake. Such connections are now a hot subject for U.S. steel researchers. Despite some extremely strong ground motions, there were no collapses of steel-framed buildings and no fatalities after the Northridge earthquake in January 1994. Within weeks of the event, however, investigations showed that more than 100 moment frame buildings sustained severe cracking of welded connections during the earthquake. The Northridge earthquake highlighted some factors that have not been serious seismic design considerations in the past. Future seismic design codes will focus on efforts to ensure that inelastic deformation, which dissipates seismic energy, takes place away from the connections. Connections are not isolated structural elements: the force and deformation demands are directly influenced by the behavior of other parts of the structural system. Designers need to analyze the preselected locations for dissipating seismic energy in the beams (structural fuses) so as to limit the forces transmitted to the joints. These analysis tools can be very sophisticated, and will not be accepted in design practices. Simplified yet sufficiently accurate tools for system analysis are a critical need.

Subject Headings: Connections | Cracking | Damage | Earthquakes | Seismic design | Steel frames |

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