An assessment of seismic design practice of steel structures in the United States since the Northridge earthquake

Abstract

AbstractThe 1994 Northridge earthquake served as a watershed event in the practice of seismic design of structural steel buildings. Damage to steel moment frame and concentrically braced buildings in this earthquake as well as similar types of damage observed in the 1995 Hyogoken‐Nambu earthquake illustrated the need to address design, construction, and quality shortcomings in design standards, methods of construction, and inspection practices. Research demonstrated that moment frame performance could be improved by shifting the location of the plastic hinge from the face of the column, use of higher notch‐tough welding electrodes, rigorous attention to proper fabrication and erection practices, and improved inspection practices emphasizing visual inspection. Changes to braced frame design provisions have emphasized development of full member strength in the connections, which has led to development of buckling restrained systems to better match tensile and compression brace capacities. This paper assesses the impact of post‐earthquake observations and some of the research initiatives that have changed the way in which structural steel seismic systems are designed. It attempts to identify the trends relative to selection of various steel seismic systems in response to perceived performance issues, limitations imposed by design standards and regulatory agencies, and economic factors. Copyright © 2004 John Wiley & Sons, Ltd.