Northridge与ChiChi地震滞回耗能谱的比较

Comparison of Hysteretic Energy Spectra in Northridge and ChiChi Earthquake

按场地类别和强震持时将水平向302条美国Northridge地震记录和339条台湾ChiChi地震记录的峰值进行规一化处理,分别采用双线型、半退化三线型和退化三线型3种恢复力模型,对单自由度(SDOF)体系进行弹塑性时程分析,研究结构动力特性和地震动参数对平均滞回耗能谱的影响.结果表明,平均滞回耗能值强烈地依赖于场地条件、强震持时和阻尼比等因素,恢复力模型和屈服强度系数对滞回耗能值的影响较小;滞回耗能值随强震持时的增长而增大,随场地特征周期的增长而增大,随阻尼比的增大而减小.Northridge地震和ChiChi地震的滞回耗能谱的形态和变化趋势相类似,峰值相差较小,由此提出了滞回耗能谱简化计算公式,并回归分析得到相关系数.

302 Northridge in USA and 339 ChiChi in Taiwan earthquake ground motion records are classified according to soil condition and duration of strong ground motion. This study is based on a great deal of nonlinear time history analysis of single degree of freedom （SI）OF） with normalized peak ground acceleration and hi-linear,semi deteriorated tri-linear and deteriorated tri-linear hysteretic models. The influence of structural dynamic character and seismic ground motion parameter on hysteretic energy is evaluated. It is discovered that mean hysteretic energy is determined by site conditions, duration of strong ground motion and damping, while hysteretic model and strength level have much less effect on hysteretic energy. The hysteretic energy increases with duration of strong ground motion and soil characteristic periods becoming longer, and decreases with damping growing larger. The shape and trend of ChiChi＇ hysteretic energy spectra is similar to Northridge＇s and there is only a little difference between them in their maximum value. Thus a simple formulation of hysteretic energy is proposed and coefficients are calculated by means of nonlinear regression analysis.