我国《建筑抗震设计规范》基底剪力系数研究

Study on seismic base shear factor in Chinese 'Code for seismic design of buildings'

介绍了基底地震剪力的影响因素及美国、新西兰、加拿大及欧洲抗震规范采用振型分解反应谱法进行分析时的基底地震剪力最小需求,并从中美规范剪力系数所考虑因素的对比及高阶振型对长周期结构基底地震剪力影响的分析中发现,剪力系数应满足2个必要条件:剪力系数应与反应谱形状(由场地类型等因素决定)相关;剪力系数应反映高阶振型的影响,即满足单调性条件。根据SEAOC的研究报告,针对我国GB 50011—2010《建筑抗震设计规范》剪力系数计算式存在的不足,提出了修正建议。对比分析表明,修正后的剪力系数计算式更符合基底地震剪力的特性,且工程适用范围更广,可为抗震规范今后的修订提供参考。

Factors affecting seismic base shear and the minimum requirements of seismic base shear for modal response spectrum analysis in the seismic codes of the United States,New Zealand,Canada and Europe were presented.Comparing the factors that were considered in seismic shear factor between the Chinese and American seismic codes and discussion about influence of higher-mode response on seismic base shear of long-period structure,it turns out that seismic shear factor should meet two necessary conditions.Firstly,seismic shear factor associated with the response spectrum shape（determined by site class etc.）.Then,seismic shear factor reflecting the effects of higher-mode and complied with the monotonicity criterion.According to the research report of the SEOAC,the amended seismic shear factor calculation formulae that can avoid the shortcomings of the original one in Chinese ＇Code for seismic design of buildings＇（GB 50011—2010） was provided.The comparative analysis shows that,the amended seismic shear factor calculation formulae can better reflect the characteristics of seismic base shear and further increase the scope of engineering application.It can provide a reference for the future revision of the seismic code.