New Standards for Seismic Design of Structural Steel

摘要

Since the first publication of the International Building Code, 5 years ago, design of seismic-force-resisting systems of structural steel in Seismic Design Categories D, E, and F has been required to conform to the requirements of the Seismic Provisions for Steel Buildings (AISC Seismic Provisions), a standard published by the American Institute of Steel Construction. The first AISC Seismic Provisions were published in the early 1990s, at a time when most steel structures were designed using allowable stress procedures and when most design of structures for seismic resistance was performed under the Uniform Building Code. At the time the first AISC Seismic Provisions were published, most engineers believed that steel structures inherently performed well in earthquakes, regardless of the precautions taken in their design and construction. Consequently, the first Seismic Provisions was a relatively thin document, with comparatively few detailed requirements. Then, on January 17, 1994, the Northridge Earthquake struck the San Fernando Valley north of Los Angeles, one of the most densely populated regions in, the United States. The Northridge earthquake caused more than dollars 30 billion of damage, and affected a wide range of construction types. However, engineers and researchers both were shocked by the discovery of brittle fracture damage in moment-resisting steel frames, a system that Was though to be among the most resistant to earthquake-induced damage.