中日欧美抗震规范结构影响系数的构成及其对塑性变形需求的影响

Composition of Structural Behavior Factors in Codes of China,Japan,Europe and USA for Earthquake-Resistance and Their Corresponding Ductility Demands

本文对中、日、欧州及美国地震规范地震力计算的结构影响系数的构成进行了分析,认为,美国的结构影响系数中包括了材料的强屈比、超静定结构体系的超强系数以及延性系数;而欧洲的结构影响系数包含了延性系数,对于延性好的结构还允许包含结构体系的超强系数;日本仅包含延性系数;我国也是仅包含延性系数。由于日本采用允许应力设计,还有一个1.4的安全系数,因此比较起来,日本的地震力最大。从结构影响系数的构成看结构在地震作用下产生塑性变形的深度,按照美国规范设计的结构塑性变形要求最高,欧洲次之,我国再次之,按照日本规范设计的结构塑性变形要求最小。

The composition of structural performance factors for base shear determination in the codes of China, Japan, Europe and USA for earthquake resistance are discussed. In USA, it includes overstrength factors of both the material and the structural system and the ductility, in EC8 it contains the ductility factor,and the structural overstrength factor in structural system with high ductility. In Japan and China, it reflects only the ductility. Because in Japan a load factor of 1.4 is introduced, it has the biggest earthquake forces for structural design. Based on the composition of the structural behavior factors, it can be deduced that the USA code puts the most severe demand on the plastic deformation capacity of structural members against earthquakes, Eurocode 8 lies on the second, and the Chinese code is on the third. The Japan code may have the least demand on the ductility although it contains similar requirements on detailing of members and joints.