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A method of structural damage identification using harmonic excitation force is presented. It considers the effects of both measurement and modelling errors in the baseline finite element model. Damage that accompanies changes in structural parameters can be estimated for a damaged structure from the change between measured vibration responses and ones calculated from the analytical model of the intact structure. In practice, modelling errors exist in the analytical model due to material and geometric uncertainties and a reduction in the degrees of freedom as well as measurement errors, making identification difficult. To surmount these problems, bootstrap hypothesis testing, which enables statistical judgment without information about these errors, was introduced. The method was validated by numerical simulation using a three‐dimensional frame structure and real vibration data for a three‐storey steel frame structure. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Single crystals of akermanite (Ca1–x
Sr
x
)2Co-Si2O7 solid solution were grown in nitrogen by the floating zone method using a lamp-image furnace. The grown crystals were 6 mm in diameter by 50 mm in length. Microprobe analyses indicate uniform strontium content x except in the initially crystallized part. Synthetic crystals with x from 0.0 to 0.3 give, at room temperature, satellite reflections and circular diffuse scatterings in the electron diffraction pattern, which are related to an incommensurate phase and microdomains, respectively. With increasing Sr content the wavelength of a modulation increases and the intensity of satellites decreases, but the intensity of circular diffuse scattering increases up to x=0.15 and then decreases until eventually the satellites and the circular diffuse scatterings disappear at x = 0.3. The circular diffuse scattering is explained by the cluster model for the transition state, proposed by De Ridder et al. (1976). 相似文献
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Toshiyuki Wakatsuki Hisao Furukawa Kazutake Kyuma 《Geochimica et cosmochimica acta》1977,41(7):891-902
Sixteen alluvial and terrace soils from Japan and Thailand were separated into six fractions ; an amorphous sesquioxide and combined organic matter fraction, crystalline sesquioxides, clay, silt, fine sand and coarse sand. Content of ten major and minor elements in these six fractions was analyzed; SiO2, A12O3, Fe2O3, MgO, CaO, K2O, TiO2, Rb2O and SrO were determined by X-ray fluorescence spectrometry, and Na2O was determined by neutron activation analysis. The clay, silt, fine sand and coarse sand mineralogy were estimated semi-quantitatively by X-ray diffraction methods.We propose three indices of geochemical maturity for the soils and test their usefulness as measures of the degree of weathering. Three concomitant factors are proposed to measure the relative resistate, hydrolyzate and oxidate nature of the major elements in the soils. 相似文献
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Aiko Furukawa Robin Spence Yutaka Ohta Emily So 《Bulletin of Earthquake Engineering》2010,8(2):451-479
Collapse of adobe buildings during an earthquakes with various earthquake intensities is analyzed using the 3-dimensional
distinct element method code developed by the first author. Firstly, we evaluate structural damage with damage index, interior-space
damage with w score, and human casualties in the collapsing buildings with three casualty criteria. Secondly, we investigate
relationships between the earthquake intensity, the structural damage, the interior-space damage, and the casualties. It is
found that the casualties have stronger correlation with the interior-space damage than the structural damage, and three vulnerability
functions, namely, structural, interior-space and casualty vulnerability functions, are proposed. Effects of reinforcing methods
on these functions are also examined. Finally, a series of analytical procedures to develop vulnerability functions and to
estimate casualties using the functions are described. 相似文献
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Sachi Furukawa Eiji Sato Yundong Shi Tracy Becker Masayoshi Nakashima 《地震工程与结构动力学》2013,42(13):1931-1949
Base isolation is a well known technology that has been proven to reduce structural response to horizontal ground accelerations. However, vertical response still remains a topic of concern for base‐isolated buildings, perhaps more so than in fixed‐base buildings as isolation is often used when high performance is required. To investigate the effects of vertical response on building contents and nonstructural components, a series of full‐scale shaking table tests were conducted at the E‐Defense facility in Japan. A four‐story base‐isolated reinforced concrete building was outfitted as a medical facility with a wide variety of contents, and the behavior of the contents was observed. The rubber base isolation system was found to significantly amplify vertical accelerations in some cases. However, the damage caused by the vertical ground motions was not detrimental when peak vertical floor accelerations remained below 2 g with three exceptions: (1) small items placed on shelves slid or toppled; (2) objects jumped when placed on nonrigid furniture, which tended to increase the response; and (3) equipment with vertical eccentricities rocked and jumped. In these tests, all equipment and nonstructural components remained functional after shaking. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Yoshihiro Furukawa Toshimori Sekine Takeshi Kakegawa 《Geochimica et cosmochimica acta》2011,75(21):6461-6472
Shock-recovery experiments on mixtures of olivine and water with gas (air) were performed in a previous study to demonstrate water-mineral interactions during impact events (Furukawa et al., 2007). The products of these former experiments were investigated in the present study using transmission electron microscopy, scanning electron microscopy, and X-ray powder diffraction with the aim of finding evidence of aqueous alteration. Serpentine formed on the surface of shocked olivine with well-developed mosaicism. The yield of serpentine depended on the water/olivine ratio in the starting material, indicating progressive serpentinization under water-rich conditions. Comminution and mosaicism were developed in shocked olivine grains. The temperature and pressure changes of the samples during the experiments were estimated by constructing Hugoniots for mixtures of olivine and water, combined with the results of an additional fracturing experiment on a shocked container. Pressures and temperatures reached 4.6-7.2 GPa and at least 230-390 °C, respectively, for 0.7 μs during in-shock compression. Post-shock temperatures reached a maximum of ∼1300 °C, when the shock wave reached the gas in the sample cavity. The serpentine formed after the post-shock temperature maximum, most likely when temperatures dropped to between 200 and 400 °C. This is the first experiment to demonstrate the formation of phyllosilicates using heat supplied by an impact. The present results and estimations suggest that phyllosilicates could form as a result of impacts into oceans as well as by impacts on terrestrial and Martian crustal rocks, and on some asteroidal surfaces, where liquid or solid H2O is available. A significant amount of phyllosilicates would have formed during the late heavy bombardment of meteorites on the Hadean Earth, and such phyllosilicates might have affected the prebiotic carbon cycle. 相似文献
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Shallow marine carbonate sediments near the Dry Tortugas undergo extensive biogeochemical diagenesis upon deposition, resulting
in postdepositional fabric comprised of micritic aggregates of clay-sized particles, a matrix of peloidal mud, and intraparticular
cementation. Freshly deposited primary skeletons, mostly Halimeda fragments, yield micritic aggregates of clay-sized particles, which then form peloidal mud fabric upon compaction. The cryptocrystalline
particles produced by micritization are later replaced by high magnesian calcite. Cementation is observed in the intra-particular
microenvironment. However, no inter-particular, grain-binding cement was detected throughout the gravity core samples investigated. 相似文献
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The heat capacity of åkermanite solid solutions was measured by a small scale adiabatic calorimeter near the incommensurate-normal (I-N) transition. The heat capacity anomalies caused by the I-N transition show the type characteristic behavior implying the presence of dynamical fluctuations. The heat capacity anomalies were observed over the whole range of the åkermanite solid solutions Ca2Mg1-xCoxSi2O7 and Ca2Mg1-x-ZnxSi2O2. With increase of Co or Zn atoms, the transition temperature, Ti, rises linearly from ca. 83° C to 220° C and to 130° C, respectively. In the system Ca2CoSi2O7-Ca2FeSi2O7 and Ca2MgSi2O7-Ca2-FeSi2O7 electronic microscopy revealed that the temperature of the heat capacity anomaly decreases with increasing Fe content, whereas the Ti rises. This unusual behavior is ascribed to the microdomains observed in high resolution lattice images. 相似文献