中日美多层屈曲约束支撑钢框架动力抗震性能比较研究

Seismic Performances of Buckling-Restrained Braced Steel Frames in China,Japan and US

根据中日美抗震设计规范建立典型多层屈曲约束支撑框架研究模型,通过结构形式、屈曲约束支撑的水平力分担率β和屈曲约束支撑框架首层剪重比CB为模型主要研究参数;并且通过弹塑性时程分析层反应值与屈曲约束支撑需求性能,进而比较中国、日本及美国钢框架的抗震设计方法;研究结果如下:(1)各模型各层层间位移角反应值R,多遇地震时R<0.75%、设防烈度地震时R<1.0%以及罕遇地震时R<1.5%,屈曲约束支撑钢框架结构具有很强的减震性能。(2)最大层剪力反应值分布形式,多遇地震时跟中日美规范静力推倒分析设计层剪力分布形式比较无明显差异。设防烈度地震、罕遇地震时,β=30%的CJ模型,日本规范Ai分布形式各层剪力计算值,能够较准确的评价强震作用下层剪力分布形式;中国和美国规范计算的各层剪力值分布形式接近强震作用下层剪力分布形式。Β=80%的US模型,最大层剪力地震反应值分布形式跟中日美规范计算的各层剪力值分布形式比较,4层以下无明显差异;4层以上地震反应值远大于静力计算层剪力值。

This paper based on the seismic design codes in China,Japan and the United States, establishes a research model which is typical multi- frame of buckling restrained brace, the main research parameters of the model are horizontal force sharing ratio of BRB(β) and the first floor shear-weight ratio of BRB(CB).Analyzing layer response value and the performance requirement of BRB through elastic-plastic time-history analysis can compare steel frame seismic design methods of China, Japan and the U.S..The research results are as follows:(1)Story-drift angle response value(R) of the layers in each model is less than 0.75% when the model is in frequent earthquake,R is less than 1.0% when the model is in moderate earthquake and R is less than 1.5% when the model is in rare earthquake, buckling restrained braced steel frame structure has a strong vibration reducing performance.(2)The distribution forms of maximum story- shear response value and design story shear calculated through push- over analysis of China,Japan and the U.S.when the building is in frequent earthquake show no obvious difference.When the model is in fortification intensity earthquake and rare earthquake, the calculated shear value of the CJ model whose β is 30% in Japanese specification Ai distribution form can be more accurately evaluating shear distribution form in strong earthquake.The distribution forms of each story shear calculated by China and the U.S. norms and story shear in strong earthquake are close.In the US model whose β is 80%,the distribution forms of maximum story-shear seismic response value and the each story shear calculated by China,Japan and the U.S. norms show no obvious difference below 4layers,but seismic response value is much larger than the story shear value calculated by static analysis above 4 layers.