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341.
Xiu Luo Hiroshi Haya Tomoaki Inaba Tomoki Shiotani 《Soil Dynamics and Earthquake Engineering》2006,26(12):1101-1110
One difficult task for the seismic diagnosis of existing structures is how to nondestructively evaluate the damage degree of invisible substructures, such as embedded foundations. To diagnose substructures efficiently, a method for nondestructive inspection is developed by applying acoustic emission (AE) technique. As a newly proposed method, characteristics of secondary AE induced by train operations were investigated, and experiments using model piles and in-situ AE monitoring of in-service railway bridges conducted under railroad traffic, from which it was demonstrated that the proposed method is practicable enough to detect invisible defects in structures. A new index, known as RTRI (ratio of Repeated Train load at the onset of AE activity to Relative maximum load for Inspection period) is proposed for structural damage qualification based on the results of in-situ AE monitoring. 相似文献
342.
Earthquake codes have been revised and updated depending on the improvements in the representation of ground motions, soils and structures. These revisions have been more frequently seen in recent years. One of the key changes in earthquake codes has been performed on the design spectra. In this paper, the design spectra recommended by Turkish Earthquake Code and three other well known codes (Uniform Building Code, Eurocode 8, and International Building Code) are considered for comparison. The main purpose of this study is to investigate the differences caused by the use of different codes in the dynamic analysis and seismic verification of given types of buildings located at code defined different sites. The differences in expressions and some important points for elastic and inelastic spectra defined by the codes are briefly illustrated in tables and figures. Periods, base shears, lateral displacements and interstory drifts for the analyzed buildings located at code defined ground type are comparatively presented. 相似文献
343.
Constantine A. Stamatopoulos Eleni G. Velgaki Arezou Modaressi Fernando Lopez-Caballero 《Bulletin of Earthquake Engineering》2006,4(3):295-318
Gravity walls retaining dry soil are modeled as a system of two bodies: (a) the gravity wall that slides along the wall-foundation soil boundary and (b) the critical soil wedge in the soil behind the wall. The strength of the system is defined by both the frictional and the cohesional components of resistance. The angle of the prism of the critical soil wedge behind the wall is obtained using the limit equilibrium method. The model accounts for changes in the geometry of the backfill soil behind the wall by considering the displacements at the end of each time step under limit equilibrium. The model shows that the standard (single) block model is over-conservative for the extreme case of critical-to-applied-seismic acceleration ratios less than about 0.30, but works well for cases where this ratio ranges between 0.5 and 0.8. The model is applied to predict the seismic displacement of gravity walls (a) tested in the shaking-table and (b) studied numerically by elaborate elasto–plastic analyses. 相似文献
344.
Ezio Faccioli 《Bulletin of Earthquake Engineering》2006,4(4):341-364
The main features of the Risk-UE project approach to assessing the ground-shaking (and related hazards) distribution within urban areas are described, as a basis for developing seismic damage scenarios for European cities. Emphasis was placed in the project on adoption of homogeneous criteria in the quantitative treatment of seismicity and in constructing the ground-shaking scenarios, despite wide differences in amount and quality of data available for the cities involved. The initial steps of the approach include treatment of the regional seismotectonic setting and the geotechnical zonation of the urban area, while the hazard assessment itself takes the form of both a deterministic analysis, and of a probabilistic, constant-hazard spectra analysis. Systematic 1D site response analyses were used, mostly in the softer soil zones, to modify (when needed) the obtained ground motion maps. Earthquake induced hazard effects, such as liquefaction and landsliding, are also briefly dealt with at the end. 相似文献
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印尼8.7级巨震后云南地震活动的频度变化 总被引:1,自引:0,他引:1
0引言
2004年12月26日在印尼苏门答腊西北近海发生了8.7级巨震,3月29日在距8.7级地震破裂区东南160km又发生了一次8.5级地震。8.7级地震发生后,余震向震中以北扩展达千米以上。如此剧烈的能量释放,对我国的地震活动有何影响是令人关注的,但清晰解答这个问题并非易事,主要原因是,一个地区的大地震发生后如何影响另一个地区地震活动的机制目前我们并不清楚。这个机制可能很复杂,涉及到应力在地壳和地幔内的传播、积累,以及与地质构造等的关系。因此,仅从时间尺度上判定一个地区的大地震对另一个地区地震活动是否有影响在认识上就存在分歧。例如,是一个地区的大地震发生后的波动在传播到另一个地区时直接触发的地震活动才被看作是影响?还是由于一个地区的大地震发生后的应力释放和调整影响到另一个地区的地震活动才被看作是影响?显然,这两方面的影响在时间尺度上存在差异。8.7级地震发生后不到20分钟,在我国云南的宾川发生了4.6级地震,其发震时间也是8.7级地震的面波到达该地区的时间(李刚等,2005); 相似文献
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地震安全性评价工程师资格考试大纲已审定通过 总被引:12,自引:0,他引:12
把美国西部地区作为参考区,采用我国地震动参数区划图工作时所使用的美国西部地区强震资料建立参考区水平向基岩短周期加速度反应谱衰减关系;采用美国南加州地区数字宽频带记录建立参考区水平向基岩长周期加速度反应谱衰减关系。与由丰富的等震线资料统计得出的我国东部地区和西部地区的地震烈度衰减关系一起,用转换方法分别得到了我国东部和西部地区水平向基岩加速度反应谱衰减关系。对该衰减关系在重大工程地震安全性评价工作中的应用提出了建议。 相似文献