考虑场地类别与强震持时的滞回耗能谱的特征分析

基于力或位移的结构抗震设计方法大多无法反映地震动持时的影响,而能量设计方法则能较好地弥补其不足。按场地类别和强震持时,将302条Northridge地震记录分为15组,对地震记录的峰值进行规一化处理,采用钢筋混凝土退化三线型恢复力模型,对单自由度体系进行弹塑性时程分析,研究场地类别、强震持时、强度屈服水平以及结构周期等因素对滞回耗能的影响。结果表明:在给定地震记录的峰值和屈服强度水平下,结构的滞回耗能依赖于场地条件和强震持时等因素;滞回耗能随强震持时的增加而增大,随场地特征周期的增加而增大。通过非线性回归分析,建立了与峰值加速度、峰值速度、强震持时相对应的简化滞回耗能谱的计算公式。

Hysteretic Energy Spectra Considering Site Type and Duration of Strong Ground Motion

Most of aseismic structural design methods based on force or displacement can't reflect the effect of duration of ground motion, but the energy-based seismic design methods can do. We classified 302 ground motion records of the Northridge earthquake into 15 groups according to site type and strong ground motion duration, analyzed the nonlinear time history of SDOF with normalized peak ground acceleration using deteriorated concrete trilinear hysteretic model, to study the influences of site type, duration of strong ground motion, level of strength and period of structural vibration on hysteretic energy. Compared with mean hysteretic energy, it is found that hysteretic energy is strongly dependent on site conditions and duration of strong ground motion for a given peak ground acceleration and strength level. Hysteretic energy will increase with increasing strong ground motion duration and site characteristic period. By means of nonlinear regression analysis, the simple computing formulation of hysteretic energy is established, in which peak ground acceleration, peak ground velocity and the duration of strong ground motion are considered.