BRB对火力发电主厂房钢筋混凝土框架柱抗震性能的影响

The Impact of the BRB on Seismic Resistance Frame Columns in Thermal Power Plant RC Structures

对两个七层火力发电厂房按8度二类抗震等级来设计计算,其中一个为钢筋混凝土框排架结构,另一个为在此基础上布置了屈曲约束支撑(BRB)的结构。对这两个结构分别进行了弹塑性时程分析,主要分析对比了两种结构体系的框架柱轴压比,层间位移角和M2、M3与轴方向滞回曲线。分析结果显示,结构经过合理布置BRB后,结构柱轴压比稍微增大,但仍然满足规范轴压比限值与抗震性能要求,BRB滞回饱满,参与耗能显著,柱参与耗能减小,主体结构安全得到保证。发现柱轴方向发生受拉情况,塑性变形容易发生,这都是构件在受集中力与跨度较大时所影响,尤其在X形BRB布置情况下较为显着,BRB在屈服前后对柱有着明显的差异。建议结构在X形BRB布置下,集中力与跨度较大和空旷时柱轴压比取值宜较保守,改善结构体系布置,适当增加柱截面也同时减小BRB截面,K形BRB布置则在屈服前后较一致,对柱轴压比影响不大。根据分析结果得出框架—BRB结构是适用于8度二类场地的建设而纯框架结构则不符合此抗震性能要求。

Two seven-story of RC frame-bent structures were studied by non-linear time history analysis in condition of seismic fortification intensity of eight degrees and site classes of type Ⅱ.One RC frame-bent structure is equipped with buckling-restrained brace （BRB） and another is un-braced.The main goal of the paper is to analyze and compare the frame column axial compression ratio,inter-story displacement angle and hysteresis curve of M2,M3 and axial direction.From the analysis results,a structure with reasonable positioning of BRB may increase the frame column axial compression ratio and at the same time meet the specification limit and seismic performance requirements.The article also found with the occurrence of axial tension in frame columns axial direction,plastic deformation is likely to occur.This is because the members affected by large concentration load and larger span especially BRB layout of type-X.The type-K BRB layout does not have much influence on the frame column axial compression ratio since it shows more consistencies before and after yielding.The analysis results show that the structure equipped with BRB is suitable in seismic fortification intensity of eight degrees and site classes of type Ⅱ but the unbrace structure cannot meet the seismic performance requirements.