The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6)...The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.展开更多
For seismic design of structure and machinery, it is important to reproduce input earthquake motions that are likely to occur at a target site. Among the various methods used for generating artificial earthquake motio...For seismic design of structure and machinery, it is important to reproduce input earthquake motions that are likely to occur at a target site. Among the various methods used for generating artificial earthquake motions, the Synthesis Method of Trigonometric Function is used widely. In this method, artificial waves are reproduced by superimposing sine waves and then adding information about amplitude and phase in the frequency domain. In the Japanese architectural design code, the amplitude is standardized as the target response spectrum, and the phase can be defined by random numbers or by the phase of one observed wave. However, a random phase is distinctly different from the phase of an actual earthquake. Further, the phase of one observed wave is confined to the phase characteristic of the artificial wave of only one specific earthquake motion. In this paper, the authors introduce a new convenient method to reproduce artificial waves that not only satisfy the standardized spectrum property but also have the time-frequency characteristics of multiple observed waves. The authors show the feature of the artificial waves, discuss the merits of the method by comparing with existing methods, and report the tendencies of the non-liuear response by using simple model.展开更多
基金financially supported by National Natural Science Foundation of China (No.51478444 & No.41472297)
文摘The Loess Plateau is an earthquake prone region of China, where the effects of loess deposit on ground motion were discovered during the 2008 Wenchuan earthquake(Ms8.0) and the 2013 Minxian-Zhangxian earthquake(Ms6.6). The field investigations, observations, and analyses indicated that large number of casualties and tremendous economic losses were caused not only by collapse and damage of houses with poor seismic performance, landslides, but also amplification effects of site conditions, topography and thickness of loess deposit, on ground motion. In this paper, we chose Dazhai Village and Majiagou Village as the typical loess site affected by the two earthquakes for intensity evaluation, borehole exploration, temporary strong motion array, micro tremor survey, and numerical analysis. The aim is to explore the relations between amplification factors and site conditions in terms of topography and thickness of loess deposit. We also developed site amplification factors of ground motion for engineering design consideration at loess sites. The results showed that the amplification effects are more predominant with increase in thickness of loess deposit and slope height. The amplification mayincrease seismic intensity by 1 degree, PGA and predominant period by 2 times, respectively.
文摘For seismic design of structure and machinery, it is important to reproduce input earthquake motions that are likely to occur at a target site. Among the various methods used for generating artificial earthquake motions, the Synthesis Method of Trigonometric Function is used widely. In this method, artificial waves are reproduced by superimposing sine waves and then adding information about amplitude and phase in the frequency domain. In the Japanese architectural design code, the amplitude is standardized as the target response spectrum, and the phase can be defined by random numbers or by the phase of one observed wave. However, a random phase is distinctly different from the phase of an actual earthquake. Further, the phase of one observed wave is confined to the phase characteristic of the artificial wave of only one specific earthquake motion. In this paper, the authors introduce a new convenient method to reproduce artificial waves that not only satisfy the standardized spectrum property but also have the time-frequency characteristics of multiple observed waves. The authors show the feature of the artificial waves, discuss the merits of the method by comparing with existing methods, and report the tendencies of the non-liuear response by using simple model.
