The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Tomoaki Nishino - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Ignitions Following 2011 Tohoku Earthquake Using Kawasumi Model
Fire Safety Science, 2014Co-Authors: Keisuke Himoto, Masumi Yamada, Tomoaki NishinoAbstract:Ignitions following the Tohoku Earthquake (2011) can be divided either into Earthquake-generated ignitions or tsunami-generated ignitions. This study analyzed the behavior of the Earthquake-generated ignitions. Ignition records of 698 municipalities of eastern Japan was collected by a questionnaire survey and found that 191 ignitions were either directly or indirectly caused by seismic motion. These records of Earthquakegenerated ignition were analyzed using the statistical model proposed by Kawasumi (Kawasumi model). Kawasumi model is a simple one-parameter model which formulates the relationship between the ignition probability p and the scale of seismic intensity θ. Seismic indices θ used in this analysis were (a) collapse ratio of houses, (b) JMA (Japan Meteorological Association) seismic intensity, (c) PGA (peak ground acceleration), (d) PGV (peak ground velocity), (e) PGD (peak ground displacement), (f) acceleration response and (g) SI (Spectral Intensity). Obtained adjusted determination coefficients were higher than 0.7 for most of the seismic indices θ except for (a) collapse ratio of houses and (e) PGD. After normalization with regard to time and season of its occurrence, the results were further compared with that of various Earthquakes (1927-1968), and the Kobe Earthquake (1995). Ignition probability p of the Tohoku Earthquake (2011) was substantially lower than that of the various Earthquakes (1927-1968). On the other hand, the difference of ignition probability p between the Tohoku Earthquake (2011) and Kobe Earthquake (1995) was relatively small.
竹脇 出 - One of the best experts on this subject based on the ideXlab platform.
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STRUCTURAL DAMAGE LOCALIZATION METHOD USING ADDITIVITY ON STORY STIFFNESS DETERIORATION DUE TO DAMAGE OF STRUCTURAL ELEMENTS
'Architectural Institute of Japan', 2018Co-Authors: 鈴木 遥也, 鍋島 国彦, 藤田 皓平, 竹脇 出Abstract:After unexpected disasters such as off the Pacific coast of Tohoku Earthquake (2011) and the Kumamoto Earthquake (2016), structural health monitoring techniques are strongly desired to evaluate the structural state of a building immediately. In the structural health monitoring system, the system identification (SI) method plays an important role in dealing with a large amount of monitoring data. As far as the SI methods are concerned, there may exist two branches classified into a modal-parameter SI and a physical-parameter SI. The main objective of the modal parameter SI is to identify the modal quantities and damping ratios. On the other hand, in the physical-parameter SI, the story stiffnesses of the objective building are directly identified from the floor response data. In order to assess the structural state of the possibly damaged building, the physical-parameter SI method is more appropriate for the structural health monitoring compared with the modal-parameter SI method. In this paper, from the viewpoint of the development of the structural health monitoring system using the physical-parameter SI method, a new structural damage localization algorithm for frame buildings is proposed based on the additivity on story stiffness deterioration caused by structural member damages. In the additivity on story stiffness deterioration, the sensitivities of story stiffnesses to structural damages of structural members are used to identify the location of damaged structural members. The additivity on the story stiffness deterioration can be proved by the Taylor series expansion of a multi-dimensional function. Based on the additivity on the story stiffness deterioration, the story deterioration of the damaged building with multiple structural members can be estimated by the superposition of the story stiffness variation due to the structural damage in a single member. In Section 3, it is shown that the story stiffnesses of a 1-bay 2-story frame are formulated by using the moment distribution method. Since the stiffness ratio of column and beam members are included explicitly in the formulated story stiffnesses, the sensitivity of the story stiffness to the stiffness of each structural member can be derived explicitly and we can understand that the story stiffness varies even if the structural members are damaged in other stories. Therefore, in the proposed damage localization method based on the additivity assumption, the location of the damaged members can be determined by evaluating the error of estimation of the story stiffness deterioration for various combinations of story stiffness deterioration for a single damaged member. The story stiffnesses of a multi-story frame are evaluated by estimating the relationship between the story shear force and the interstory drift derived by the time-history record of floor accelerations. In order to evaluate the story stiffness reliably, it is desirable to obtain the stationary floor responses. For denoising the observed response data, the singular value decomposition using low-rank approximation is applied to the floor acceleration records. It is confirmed that the relationship between the story shear force and the interstory drift can be derived smoothly by denoising, which is important to evaluate the story stiffness. In numerical examples, both a symmetric 2-bay 5-story frame and a setback 5-story frame subjected to two different excitation scenarios such as the ground motion and the top floor forced excitation are used to investigate the validity of the proposed damage localization method in Section 4. For the practical application to possibly damaged buildings, it is assumed that the damage severities of structural members and the number of damaged members are unknown. These problems are solved by the proposed damage localization method by improving the searching algorithm based on the superposition of story stiffness variation using the additivity assumption
Keisuke Himoto - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Ignitions Following 2011 Tohoku Earthquake Using Kawasumi Model
Fire Safety Science, 2014Co-Authors: Keisuke Himoto, Masumi Yamada, Tomoaki NishinoAbstract:Ignitions following the Tohoku Earthquake (2011) can be divided either into Earthquake-generated ignitions or tsunami-generated ignitions. This study analyzed the behavior of the Earthquake-generated ignitions. Ignition records of 698 municipalities of eastern Japan was collected by a questionnaire survey and found that 191 ignitions were either directly or indirectly caused by seismic motion. These records of Earthquakegenerated ignition were analyzed using the statistical model proposed by Kawasumi (Kawasumi model). Kawasumi model is a simple one-parameter model which formulates the relationship between the ignition probability p and the scale of seismic intensity θ. Seismic indices θ used in this analysis were (a) collapse ratio of houses, (b) JMA (Japan Meteorological Association) seismic intensity, (c) PGA (peak ground acceleration), (d) PGV (peak ground velocity), (e) PGD (peak ground displacement), (f) acceleration response and (g) SI (Spectral Intensity). Obtained adjusted determination coefficients were higher than 0.7 for most of the seismic indices θ except for (a) collapse ratio of houses and (e) PGD. After normalization with regard to time and season of its occurrence, the results were further compared with that of various Earthquakes (1927-1968), and the Kobe Earthquake (1995). Ignition probability p of the Tohoku Earthquake (2011) was substantially lower than that of the various Earthquakes (1927-1968). On the other hand, the difference of ignition probability p between the Tohoku Earthquake (2011) and Kobe Earthquake (1995) was relatively small.
A. K. Ward - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Strain in a South African Gold Mine Produced by the 2011 Tohoku Earthquake
International Association of Geodesy Symposia, 2015Co-Authors: Makoto Okubo, Hiroshi Ogasawara, Shigeru Nakao, Osamu Murakami, Hiroshi Ishii, A. K. WardAbstract:The 2011 Tohoku Earthquake (2011/03/11 05:46:18 UT, M W 9.0) produced huge permanent displacements of up to 50 m and dynamic strain of up to 10−5 in the near-field. We observed dynamic strain (10−7) produced by this Earthquake at a depth of 1 km in a gold mine in the Republic of South Africa at a distance of more than 14,000 km (125.25∘) from epicenter. The dynamic strain was observed by two Ishii-type borehole strainmeters about 30 m apart on opposite sides of a fault filled with gouge of several decimeters thickness, allowing the response of the fault to be investigated. The Tohoku Earthquake seismic waves passed through the gold mine outside blasting hours, allowing us to analyze the tele-seismic body waves and the surface waves that circled the globe several times (R3 − R5 and G3 − G5, \(\sim 10^{-8}\)). We discuss the fault deformation associated with the dynamic strains by the wave packets. The seismograms of some sub-parallel components of the two strainmeters installed on the opposite sides of the fault appeared similar, although with differences on the order of \(\sim 10^{-8}\). These differences may imply a complex response of the fault (fault rheology; i.e. not only elastic, but perhaps plastic or even indicating the effects of fluid).
Fabian Bonilla - One of the best experts on this subject based on the ideXlab platform.
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Inversion of nnolinear soil parameters during the 2011 Tohoku, Japan
2012Co-Authors: Florent De Martin, Hiroshi Kawase, Fabian BonillaAbstract:This paper presents the inversion of linear and equivalent linear soil profile (i.e., S-wave velocity and damping factor) at the KiK-net station MYGH10 during the Great Tohoku Earthquake, 2011. Due to possible strong 2D or 3D topographic effects at the station located close to mountainous areas, we carefully select weak motions that present few of those effects. Among 50 weak motions, only 5 are selected to check the linear profile of the site. Then, the equivalent linear soil profile during the main shock is inverted, showing very interesting nonlinear effects, such as bedrock nonlinearity.