Commentary for New LRFD Seismic Criteria

1986年，新的AISC荷载和抗力系数设计规范(LRFD)的出台，使钢结构建筑的极限状态设计取代了传统的许用应力设计。LRFD代表了钢设计技术的重大进步，该技术基于安全可靠性概念和对因数载荷和极限状态的明确考虑。但是，本规范主要适用于受重力或风荷载控制的设计。因此，在高地震和中等地震活动的地区，有必要补充特殊的细节要求，以提供与地震风险程度相称的足够的结构延性和能量吸收。目前可用的抗震详图条款是以许用应力为单位的，因此不能直接与LRFD兼容。AISC的一个专家小组委员会最近首次以LRFD格式制定了一套抗震设计规定。在为LRFD设计应用出版和广泛分发这份所需的文件之前，只有准备好适当的评论。该项目将支持在未来3-6个月内对评论进行协调一致的努力，以完成本文件并满足工程师和建筑规范官员的迫切需求。这将有助于保持适当的设计实践和安全水平，因为LRFD用于地震条件。这些任务将包括审查和列出相关研究参考文献，彻底解释标准的背景材料和实际影响，以及讨论/制作条款未直接涵盖的其他一般性建议。

In 1986, the new AISC Load and Resistance Factor Design (LRFD) Specification was introduced which makes the limit state design of steel buildings as an alternate to the traditional Allowable Stress Design. LRFD represents a major advancement in steel design technology that is based on safety reliability concepts and an explicit consideration of factored loads and limit states. However, the Specification is primarily intended for designs governed by gravity or wind loads. Thus, in regions of high and moderate seismicity, supplemental special detailing requirements are necessary to provide adequate structural ductility and energy absorption commensurate with the degree of earthquake risk. The currently available seismic detailing provisions are in allowable stress terms and, therefore, are not directly compatible with LRFD. The development of a set of seismic design provisions, for the first time in LRFD format, has recently been completed by an expert AISC Subcommittee. Only the preparation of an appropriate Commentary remains before this needed document can be published and broadly distributed for LRFD design applications. This project will support a concerted effort over the next 3-6 months on the Commentary to finish this document and satisfy the urgent needs of engineers and building code officials. This will help maintain proper design practice and safety levels as LRFD is used for seismic conditions. The tasks will include review and listing of related research references, thorough explanation of background material and practical implications of criteria, and discussion/artwork of additional general suggestions not covered directly by the provisions.