Influence of the column-to-beam flexural strength ratio on the failure mode of beam-column connections in RC frames

The column-to-beam flexural strength ratio(CBFSR)has been used in many seismic codes to achieve the strong column-weak beam(SCWB)failure mode in reinforced concrete(RC)frames,in which plastic hinges appear earlier in beams than in columns.However,seismic investigations show that the required limit of CBFSR in seismic codes usually cannot achieve the SCWB failure mode under strong earthquakes.This study investigates the failure modes of RC frames with different CBFSRs.Nine typical three-story RC frame models with different CBFSRs are designed in accordance with Chinese seismic codes.The seismic responses and failure modes of the frames are investigated through time-history analyses using 100 ground motion records.The results show that the required limit of the CBFSR that guarantees the SCWB failure mode depends on the beam-column connection type and the seismic intensity,and different types of beam-column connections exhibit different failure modes even though they are designed with the same CBFSR.Recommended CBFSRs are proposed for achieving the designed SCWB failure mode for different types of connections in RC frames under different seismic intensities.These results may provide some reference for further revisions of the SCWB design criterion in Chinese seismic codes.     

基于烈度指标的核电厂地震预警停堆参数研究

核电厂在遭遇超设计基准地震时需要考虑安全停堆,以避免造成核泄漏事故。采用地震动的峰值加速度参数(PGA)作为判别停堆的参数具有一定的局限性,PGA参数不能反映地震动的频谱和持时特征,因而可能引起不必要的停堆。针对此问题,基于我国本土大量实际强震记录,遴选出7种典型的工程相关地震动参数,进而基于地震烈度指标,分析发现地震动的标准累计绝对速度参数能更好地表征地震对核电厂的整体潜在破坏能力,适合作为判别停堆的参数,然后提出两种确定预警参数阈值的方法,最终建议考虑我国强震数据特征的核电厂判别停堆的预警参数阈值,为我国核电厂的地震安全停堆参数的确定提供了参考。     

基于地震观测数据的结构损伤水平表征参数研究

为了能在震后更好地利用测得的结构动力响应参数快速对结构损伤程度进行评估,文中挑选了最大层间位移角、自振频率相对改变量和顶层加速度放大系数3个参数,分析结构损伤指数与3个参数之间的相关性,并且提出了一种组合结构体系参数.结果表明,结构损伤指数与最大层间位移角的相关性为高度相关,与自振频率相对改变量和顶层加速度放大系数的相...