(同济大学土木工程防灾国家重点实验室，上海 200092)
［摘要］比较了中国、美国、日本、欧洲抗震设计规范概率基础、设防水准、设计准则、设防目标和阻尼比，针对钢框架结构比较了中美日欧地震作用的折减、截面宽厚比限值、梁柱刚接节点的塑性转动能力要求和层间位移角限值，然后提出了钢结构抗震设计方法建议：将低延性结构以外的结构体系划分为四个延性类别，针对各延性类别的结构提出塑性构件板件宽厚比限值和构件长细比限值以及梁柱节点形式及其塑性转动能力的要求；以50年超越概率10%的设防地震为抗震设计验算的基准，根据结构延性类别将设防地震的弹性地震作用折减为设计地震作用，用于构件内力验算；针对“小震不坏、中震可修、大震不倒”的设防目标提出了小震弹性层间位移和中震、大震弹塑性层间位移的三阶段验算要求。该建议可以解决我国现行抗震规范GB50011—2001中存在的问题，提高我国抗震钢结构的合理性和经济性。
［关键词］抗震延性设计方法；设计规范比较；概率基础；抗震设防目标；地震作用
Discussion and recommendation on seismic design for steel structures
Shen Zuyan, Sun Feifei(State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China)
Abstract:Seismic design codes of China, the United States, Japan and European Union were firstly compared in terms of probability basis, seismic fortification level, design criteria, design target and damping ratio. Seismic design requirements for steel moment frames according to the above codes were then compared regarding seismic response reduction, width-to-thickness ratio limit for beam/column cross sections, plastic rotation capacity of beam-to-column moment connections and inter-story drift limit. A proposal of seismic design method for steel structures in China was hence put forward as follows: all the structural systems other than low ductile structures were classified as 4 ductility categories; width-to-thickness ratio limits for plastic members, slenderness ratio limits for plastic members, requirements for beam-to-column moment connection types and their plastic rotation capacities were set forth with respect to each structural ductility category; earthquakes fortified with an exceedence probability of 10% in 50 years were chosen as design earthquakes, elastic effect of which was reduced as design earthquake effect according to the ductility category of a target structure and then applied for the design check of structural members; three-staged design check requirements were given as elastic inter-story drift limits under frequent earthquakes, elasto-plastic inter-story drift limits under design and rare earthquakes, corresponding to the seismic fortification objectives of keeping the structures “no damage under frequent earthquakes, repairable under design earthquakes and no collapse under rare earthquakes”. The proposal was applicable to solve inherent deficiencies in Chinese present seismic design code GB50011—2001 and to highly improve the rationality and economic efficiency of earthquake-resistant steel structures in China.
Keywords:seismic ductility design method； design code； probability basis； seismic fortification objective； seismic action
作者简介：沈祖炎，中国工程院院士，教授，Email:zyshen@tongji.edu.cn。
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