Horizontal and vertical components of earthquake ground motions at liquefiable sites

✍ Scribed by J. Yang; T. Sato; S. Savidis; X.S. Li

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 426 KB
• Volume: 22
• Category: Article
• ISSN: 0267-7261
• DOI: 10.1016/s0267-7261(02)00010-6

✦ Synopsis

Field observations on ground motions from recent earthquakes imply that current knowledge is limited with regard to relating vertical and horizontal motions at lique®able sites. This paper describes a study with the purpose of clarifying this emerging issue to some extent. A series of numerical analyses is carried out on a lique®able soil deposit with a veri®ed, fully coupled, nonlinear procedure. It is shown that the transformation of vertical motions in the deposit differs considerably from the transformation of horizontal motions. Both the amplitude and frequency content of the horizontal motions are strongly dependent on the shaking level or the associated nonlinear soil behavior. The transfer function for vertical motions is however likely to be independent of the intensity of input motions; no reduction in the amplitude occurs even in the case of strong shaking. The results are shown to be in consistence with the laboratory observations on shaking table tests and recent ®eld observations that less nonlinearity exists for vertical motions. It is also shown that the possibility exists for using information on spectral ratios between the horizontal and vertical surface motions to quickly identify in situ soil behavior and liquefaction that are not readily covered by conventional ®eld or laboratory experimentation procedures.