基于动力能力谱法的RC结构位移放大系数

Structural displacement amplification factor of RC frames based on the dynamic capacity spectrum method

结构位移放大系数是预测结构在某一地震设防水准作用下的最大弹塑性变形,从而指导结构设计的参数。我国现行抗震设计规范尚未引入结构位移放大系数。考虑6、7、8三个设防烈度,设计了3、5、8、10、12层共15个钢筋混凝土框架结构,建立其有限元模型,并采用结构振动台试验对有限元模型进行验证,进而对结构在地震作用下的反应进行分析。采用文中提出的动力能力谱方法,研究按我国抗震设计规范设计的RC框架结构在不同设防水准下的位移放大系数需求值,并与传统静力能力谱法得到的位移放大系数需求值进行对比分析。6、7、8度设防的RC框架结构的位移放大系数需求值在中震作用下分别为0.51-1.91、0.49-1.93、0.56-2.24;在大震作用下分别为1.28-4.82、1.40-4.89、1.37-5.56。中震作用下,按我国抗震设计规范设计的钢筋混凝土框架结构未发生整体屈服,表明我国抗震设计规范比较保守。

Structural displacement amplification factor（ DAF） is the key factor in seismic design,which is used to predict maximum inelastic deformations of structures under earthquake excitation. However,DAF has not been introduced in the current Chinese seismic design code. In this paper,15 RC frame buildings which were 3-,5-,8-,10-,12-story buildings in different seismic fortification intensity Ⅵ,Ⅶ,Ⅷ were designed according to the Code for Seismic Design of Buildings GB 50011—2010. The FE models of these buildings were modeled and structural seismic response was analyzed. Shaking table test of a RC frame structure has been accomplished and the FE models were verified and validated. The ＂demand ＂ values of the structural DAF of these RC frames were evaluated by the dynamic capacity spectrum method,and the analysis results were compared with that analyzed by the traditional static capacity spectrum method. For the designed RC frames in the seismic fortification intensity VI,VII,VIII zones,the ranges of demand values of structural DAF are 0. 51- 1. 91,0. 49- 1. 93,and 0. 56- 2. 24 respectively when they are under fortification earthquakes. The ranges of demand values of structural DAF are 1. 18- 4. 05,1. 33- 3. 45,and 1. 42- 2. 66 respectively when they are under rare earthquakes. The overall yield of the codified designed RC frames under fortification earthquakes has not occurred. And it is shown that the Chinese seismic design code is conservative.