为克服筒仓结构在地震易损性评估时需要进行大量非线性时程分析的不足,采用基于耐震时程法(endurance time method,ETM)的易损性分析方法对筒仓结构进行易损性的快速评估。以IV类场地柱承式筒仓为研究对象,选取实际天然地震动记录为目...为克服筒仓结构在地震易损性评估时需要进行大量非线性时程分析的不足,采用基于耐震时程法(endurance time method,ETM)的易损性分析方法对筒仓结构进行易损性的快速评估。以IV类场地柱承式筒仓为研究对象,选取实际天然地震动记录为目标反应谱合成3条耐震时程曲线,利用有限元软件ABAQUS建立柱承式筒仓模型并输入耐震时程曲线,将ETM分析结果与增量动力分析方法(incremental dynamic analysis,IDA)结果进行对比。结果表明:ETM分析结果与IDA分析结果的中位值相匹配,满足筒仓结构抗震性能分析精度要求;筒仓不同支承柱在地震作用下的基底剪力分配情况与储料质量无关,仅取决于支承柱位置;ETM所得的筒仓地震易损性曲线与IDA易损性曲线基本吻合,耐震时程法可作为柱承式筒仓抗震性能分析、预测和评估的高效方法。展开更多
6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples we...6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be （10]-4） plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.展开更多
文摘为克服筒仓结构在地震易损性评估时需要进行大量非线性时程分析的不足,采用基于耐震时程法(endurance time method,ETM)的易损性分析方法对筒仓结构进行易损性的快速评估。以IV类场地柱承式筒仓为研究对象,选取实际天然地震动记录为目标反应谱合成3条耐震时程曲线,利用有限元软件ABAQUS建立柱承式筒仓模型并输入耐震时程曲线,将ETM分析结果与增量动力分析方法(incremental dynamic analysis,IDA)结果进行对比。结果表明:ETM分析结果与IDA分析结果的中位值相匹配,满足筒仓结构抗震性能分析精度要求;筒仓不同支承柱在地震作用下的基底剪力分配情况与储料质量无关,仅取决于支承柱位置;ETM所得的筒仓地震易损性曲线与IDA易损性曲线基本吻合,耐震时程法可作为柱承式筒仓抗震性能分析、预测和评估的高效方法。
基金Projects(2006AA03A145,2007AA03Z405) supported by the National High-Tech Research and Development Program of ChinaProjects(50721002,50802053) supported by the National Natural Science Foundation of ChinaProject (707039) supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China
文摘6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be （10]-4） plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.
