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51.
52.
在我国烈度表中提到的房屋指的是未经过抗震设计或加固的单层或数层的砖混和砖木房屋.但是随着我国经济的发展,这类房屋的数量在逐渐减少,能够根据抗震设防房屋的破坏情况进行烈度评定对目前的地震现场工作具有重要意义.本文通过震害矩阵和平均震害指数的关系,尝试利用框架结构和砖混结构的震害矩阵得到设防烈度——震害指数的拟合关系,建立不同抗震设防水准的框架结构和砖混结构的烈度评定标准,并利用近年来9次中国大陆地震的烈度评定结果对该评定标准进行验证.本文评定的结果与这些地震现场评定结果基本一致.本研究结果可作为在我国抗震设防地区利用多种结构形式的建筑物破坏情况进行烈度评定的依据 相似文献
53.
Seasonal and event variations in stream channel area and the contributions of channel precipitation to stream flow were studied on a 106‐ha forested headwater catchment in central Pennsylvania. Variations in stream velocity, flowing stream surface width and widths of near‐stream saturated areas were periodically monitored at 61 channel transects over a two‐year period. The area of flowing stream surface and near‐stream saturated zones combined, ranged from 0·07% of basin area during summer low flows to 0·60% of total basin area during peak storm flows. Near‐stream saturated zones generally represented about half of the total channel area available to intercept throughfall and generate channel precipitation. Contributions of routed channel precipitation from the flowing stream surface and near‐stream zones, calculated using the Penn State Runoff Model (PSRM, v. 95), represented from 1·1 to 6·4% of total stream flow and 2·5–29% of total storm flow (stream flow–antecedent baseflow) during the six events. Areas of near‐stream saturated zones contributed 35–52% of the computed channel precipitation during the six events. Channel precipitation contributed a higher percentage of stream flow for events with low antecedent baseflow when storm flow generated by subsurface sources was relatively low. Expansion of channel area and consequent increases in volumes of channel precipitation with flow increases during events was non‐linear, with greater rates of change occurring at lower than at higher discharge rates. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
54.
1985年在甘肃文县屯寨乡洋汤寨的天池庙的大樑上发现了一条新的关于1879年7月1日武都8级地震的新的历史记载。该记载表明武都8级地震在这里的地震烈度至少达到了Ⅹ度。 相似文献
55.
<正>Ground motion records are often used to develop ground motion prediction equations(GMPEs) for a randomly oriented horizontal component,and to assess the principal directions of ground motions based on the Arias intensity tensor or the orientation of the major response axis.The former is needed for seismic hazard assessment,whereas the latter can be important for assessing structural responses under multi-directional excitations.However,a comprehensive investigation of the pseudo-spectral acceleration(PSA) and of GMPEs conditioned on different axes is currently lacking.This study investigates the principal directions of strong ground motions and their relation to the orientation of the major response axis, statistics of the PSA along the principal directions on the horizontal plane,and correlation of the PSA along the principal directions on the horizontal plane.For these,three sets of strong ground motion records,including intraplate California earthquakes,inslab Mexican earthquakes,and interface Mexican earthquakes,are used.The results indicate that one of the principal directions could be considered as quasi-vertical.By focusing on seismic excitations on the horizontal plane,the statistics of the angles between the major response axis and the major principal axis are obtained;GMPEs along the principal axes are provided and compared with those obtained for a randomly oriented horizontal component;and statistical analysis of residuals associated with GMPEs along the principal directions is carried out. 相似文献
56.
本文按不同设防烈度设计10层框架-剪力墙结构,计算其不同设防烈度下的土建成本。在设防烈度8度以下,设防水准提高一个等级,土建成本增加比例小于8.61%,增加成本占房屋售价的比例小于0.75%。采用框架-剪力墙结构土建成本较小的增加,可获得设防水准一个等级的提高。从另一个角度说,在减少建筑面积很小的情况下,房屋的抗震设防水准可获得一个等级的提高。 相似文献
57.
58.
Apparent fracture toughness in Mode I of microcracking materials such as rocks under confining pressure is analyzed based
on a cohesive crack model. In rocks, the apparent fracture toughness for crack propagation varies with the confining pressure.
This study provides analytical solutions for the apparent fracture toughness using a cohesive crack model, which is a model
for the fracture process zone. The problem analyzed in this study is a fluid-driven fracture of a two-dimensional crack with
a cohesive zone under confining pressure. The size of the cohesive zone is assumed to be negligibly small in comparison to
the crack length. The analyses are performed for two types of cohesive stress distribution, namely the constant cohesive stress
(Dugdale model) and the linearly decreasing cohesive stress. Furthermore, the problem for a more general cohesive stress distribution
is analyzed based on the fracture energy concept. The analytical solutions are confirmed by comparing them with the results
of numerical computations performed using the body force method. The analytical solution suggests a substantial increase in
the apparent fracture toughness due to increased confining pressures, even if the size of the fracture process zone is small. 相似文献
59.
INTRODUCTIONAs registered by the seismic network of the China Earthquake Administration and the regionalnetworkof Xizang(Tibet) Autonomous Region,anMS5·7 earthquaketook place between Bomi countyand Medog county, Tibet on August 18 , 2003·The China Earthquake Administration sent anearthquake site investigation team to the stricken region immediately after the earthquake . Theinvestigationteamconsistedjointly of personnel fromthe Earthquake Administration of Xizang (Tibet)Autonomo… 相似文献
60.
1998年5月29日皮山县发生6.2级地震,震中距皮山县城约39km,震源深度为32km,烈度分布区为北西-南东走向的椭圆形,极震区烈度为Ⅶ度,个别点为Ⅷ度,地震使皮山县县城,9个乡,2个镇,2个农场,墨玉县部分地区遭到不同程度的损失。共计受伤人数为26人,其中重伤为2人,无家可归者人数为5566人,1392户,牲畜死亡4454头。地震造成的直接经济损失达5486.75万元。 相似文献