本文描述强震地面运动持续时间的几个经验模型。我们将运动函数,f(t)的持续时间定义为积分inegtral from n=0 to 1(f^2(τ)dτ)达到其最终数值的重要部分的时间间隔的总和,此处,f(t)为加速度、速度或位移。所有记录均通过12个窄滤波器...本文描述强震地面运动持续时间的几个经验模型。我们将运动函数,f(t)的持续时间定义为积分inegtral from n=0 to 1(f^2(τ)dτ)达到其最终数值的重要部分的时间间隔的总和,此处,f(t)为加速度、速度或位移。所有记录均通过12个窄滤波器进行带通滤波,而强震地面运动的持续时间系在这些频带分别进行研究。除了震级、震中距等传统参数之外,还考虑其他三个参数,这些参数描述围绕着记录台站的沉积盆地的几何形状。文中说明沉积物的存在怎样延长对应于某些频率的持续时间。这一延长可近似表为沉积河谷的深度和宽度的一个耦联的二次函数,同时表为在台站处能反射传到台站的地震波的岩石所对应的角的线性函数。最大延长发生在沉积物的深度和宽度为中等时(深度为2～3km,宽度为30～50km)。当频率接近于1Hz时,附加的持续时间可大到6～7秒。文中研究了形成强震运动的总的持续时间的强震运动各个时间间隔的长度和数目,结果表明,附加的持续时间可解释为波由沉积河谷的底部和侧边的多次反射所致。展开更多
We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for ...We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.展开更多
本文针对加州El Centro Imperial County服务大厦进行了震后反应分析,此大厦在1979年10月15日Imperial Valley地震中受到严重的破坏,随后被拆除。分析中应用记录到的基底输入加速度和现代标准线性动力分析程序,结果表明,危险柱子上的力...本文针对加州El Centro Imperial County服务大厦进行了震后反应分析,此大厦在1979年10月15日Imperial Valley地震中受到严重的破坏,随后被拆除。分析中应用记录到的基底输入加速度和现代标准线性动力分析程序,结果表明,危险柱子上的力超过极限承载力,而可以预期的结果,主要是脆性受压破坏。地震时产生的侧力远远超过建筑规范规定的拟静力设计力。研究结果还表明,柱的破坏受到反应的三维性质的强烈影响,它导致危险柱子中的三轴弯曲。展开更多
文摘本文描述强震地面运动持续时间的几个经验模型。我们将运动函数,f(t)的持续时间定义为积分inegtral from n=0 to 1(f^2(τ)dτ)达到其最终数值的重要部分的时间间隔的总和,此处,f(t)为加速度、速度或位移。所有记录均通过12个窄滤波器进行带通滤波,而强震地面运动的持续时间系在这些频带分别进行研究。除了震级、震中距等传统参数之外,还考虑其他三个参数,这些参数描述围绕着记录台站的沉积盆地的几何形状。文中说明沉积物的存在怎样延长对应于某些频率的持续时间。这一延长可近似表为沉积河谷的深度和宽度的一个耦联的二次函数,同时表为在台站处能反射传到台站的地震波的岩石所对应的角的线性函数。最大延长发生在沉积物的深度和宽度为中等时(深度为2～3km,宽度为30～50km)。当频率接近于1Hz时,附加的持续时间可大到6～7秒。文中研究了形成强震运动的总的持续时间的强震运动各个时间间隔的长度和数目,结果表明,附加的持续时间可解释为波由沉积河谷的底部和侧边的多次反射所致。
文摘We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.
文摘本文针对加州El Centro Imperial County服务大厦进行了震后反应分析,此大厦在1979年10月15日Imperial Valley地震中受到严重的破坏,随后被拆除。分析中应用记录到的基底输入加速度和现代标准线性动力分析程序,结果表明,危险柱子上的力超过极限承载力,而可以预期的结果,主要是脆性受压破坏。地震时产生的侧力远远超过建筑规范规定的拟静力设计力。研究结果还表明,柱的破坏受到反应的三维性质的强烈影响,它导致危险柱子中的三轴弯曲。
