1,721,013 research outputs found
IDENTIFICATION OF RESTORING FORCE CHARACTERISTICS OF NONLINEAR SOIL-STRUCTURE SYSTEM
No full textWe here report a method to identify the nonlinear restoring force characteristicsof multidegree-of-freedom soil-structure system.Because the soil-structure system under the seismic loading usually exhibitsvarious hysteretic behaviour and has different histeresis loop for the soil and thestructure, many restoring force models of the soil-structure system are proposed.When we identify the restoring force characteristics of soil-structure system, however, it is convenient to use only one restoring force model. In this paper, weadopt a versatile model which can be applied to a large class of hysteretic systemsand identify the model parameters with extended Kalman filter technique.After describing the formulation of identification and showing the validity ofthis method by the numerical simulation, we applied this method to identify therestoring force characteristics using the observation records which were obtainedthrough the hybrid experiment of soil-foundation structure system.We here report a method to identify the nonlinear restoring force characteristicsof multidegree-of-freedom soil-structure system.Because the soil-structure system under the seismic loading usually exhibitsvarious hysteretic behaviour and has different histeresis loop for the soil and thestructure, many restoring force models of the soil-structure system are proposed.When we identify the restoring force characteristics of soil-structure system,however, it is convenient to use only one restoring force model. In this paper, weadopt a versatile model which can be applied to a large class of hysteretic systemsand identify the model parameters with extended Kalman filter technique.After describing the formulation of identification and showing the validity ofthis method by the numerical simulation, we applied this method to identify therestoring force characteristics using the observation records which were obtainedthrough the hybrid experiment of soil-foundation structure system
HYBRID EXPERIMENT ON NONLINEAR RESTORING FORCE OF PILE FOUNDATIONS
No full textA hybrid study of nonliner, seismic soil-structure interaction was made by anumerical analysis of the governing equations of dynamic equilibrium, in which thenonlinear stiffness of the system was evaluated experimentally by pseudo-dynamictesting and the frequency dependence of the dynamic characteristics were taken intoaccount by use of a new time domain numerical integration scheme based onHilbert transformation in the frequency domain. 1-pile and 2-pile models of fourlarge scale foundations were used. The mechanical characteristics of the systemswere determined from static and forced vibration dynamic tests. An amplitudescaling technique was used for the three accelerograms obtained.A hybrid study of nonliner, seismic soil-structure interaction was made by anumerical analysis of the governing equations of dynamic equilibrium, in which thenonlinear stiffness of the system was evaluated experimentally by pseudo-dynamictesting and the frequency dependence of the dynamic characteristics were taken intoaccount by use of a new time domain numerical integration scheme based onHilbert transformation in the frequency domain. 1-pile and 2-pile models of fourlarge scale foundations were used. The mechanical characteristics of the systemswere determined from static and forced vibration dynamic tests. An amplitudescaling technique was used for the three accelerograms obtained
IDENTIFICATION OF FAULT RUPTURE MECHANISMS USING KALMAN FILTER
No full textThe Kalman filter is applied to deconvolute a seismic wave into a system response functionand a train of impulses. Based on several criteria of minimum error, we propose a method toidentify a rupture process of a fault using the deconvoluted train of impulses.A simulated wave and a waveform recorded in a blasting are analized in order to examine thevalidity of the proposed deconvolution method. The records obtained at seven JMA local stationsduring Nihonkai Chubu Earthquake are used to identify its fault mechanism. Since deconvolutedseven trains of impulses contain informations about the fault mechanism, the rupture processdefined by such focal parameters as the rupture velocity, the starting point of rupture, the directionof the rupture propagation and the rise time can be estimated by minimizing the error betweendeconvoluted trains of impulses and theoretically calculated ones by selecting proper values of faultparameters in the rupture process.The identified rupture process compares well with that investigated from different approach.The Kalman filter is applied to deconvolute a seismic wave into a system response functionand a train of impulses. Based on several criteria of minimum error, we propose a method toidentify a rupture process of a fault using the deconvoluted train of impulses.A simulated wave and a waveform recorded in a blasting are analized in order to examine thevalidity of the proposed deconvolution method. The records obtained at seven JMA local stationsduring Nihonkai Chubu Earthquake are used to identify its fault mechanism. Since deconvolutedseven trains of impulses contain informations about the fault mechanism, the rupture processdefined by such focal parameters as the rupture velocity, the starting point of rupture, the directionof the rupture propagation and the rise time can be estimated by minimizing the error betweendeconvoluted trains of impulses and theoretically calculated ones by selecting proper values of faultparameters in the rupture process.The identified rupture process compares well with that investigated from different approach
DEVELOPMENT OF A DW-FE HYBRID METHOD FOR THE SEISMIC RESPONSE ANALYSIS OF THE GROUND WITH IRREGULAR INTERFACES
No full textA Discrete Wavenumber-Finite Element (DW-FE) hybrid method for the problem of SH and P-SV wave inputs was developed. To check the validity of the DW-FE hybrid method, we compared it with a DW and a FE-BE hybrid methods. For the three different impedance ratios and incident angles, transfer functions were calculated. We defined calculation errors for stresses and displacements on the interfaces, and investigated whether the given boundary conditions were satisfied or not. As the results, the DW-FE hybrid method is a powerful tool with which to reduce the calculation cost and time for the seismic response of the ground with irregular interfaces.A Discrete Wavenumber-Finite Element (DW-FE) hybrid method for the problem of SH and P-SV wave inputs was developed. To check the validity of the DW-FE hybrid method, we compared it with a DW and a FE-BE hybrid methods. For the three different impedance ratios and incident angles, transfer functions were calculated. We defined calculation errors for stresses and displacements on the interfaces, and investigated whether the given boundary conditions were satisfied or not. As the results, the DW-FE hybrid method is a powerful tool with which to reduce the calculation cost and time for the seismic response of the ground with irregular interfaces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
MODELING OF SPATIAL VARIATION OF SEISMIC GROUND NOTION ON LAYERD MEDIA HAVING AN IRREGULAR INTERFACE
No full textLifeline systems such as buried gas or water pipelines will be heavily damagedduring an earthquake if the relative displacement between two points on the groundis large. These long underground structures are affected by the profile of thesurface ground. In particular, if an irregular interface exists in the layered media, ground motion above this interface may be amplified. The mean powers of wavesobserved on the points at surface ground are not constant and an assumption of thestationary process does not hold true.We first simulated the surface ground motion of layered media that had anirregular interface by the Discrete Wave Number Method. The mean powers andcross correlations were examined with simulated waveforms, and the shape of theirregular interface was identified.The relative displacements between two observation points were modeled by theuse of spatial correlation and autocorrelation functions by replacing a simple basinwith two sets of layered media.Lifeline systems such as buried gas or water pipelines will be heavily damagedduring an earthquake if the relative displacement between two points on the groundis large. These long underground structures are affected by the profile of thesurface ground. In particular, if an irregular interface exists in the layered media,ground motion above this interface may be amplified. The mean powers of wavesobserved on the points at surface ground are not constant and an assumption of thestationary process does not hold true.We first simulated the surface ground motion of layered media that had anirregular interface by the Discrete Wave Number Method. The mean powers andcross correlations were examined with simulated waveforms, and the shape of theirregular interface was identified.The relative displacements between two observation points were modeled by theuse of spatial correlation and autocorrelation functions by replacing a simple basinwith two sets of layered media
STUDY ON FAILURE MECHANISM AND STRENGTH INCREMENT EFFECT OF MASONRY WALLS MADE OF INTERLOCKING BRICKS
No full text組積造構造物の補強方法として, 直方体煉瓦でなく凹凸のある煉瓦を用いて煉瓦同士の噛み合いに期待するものが提案されているが, その効果について十分な検証はなされていない. 本研究は, 直方体煉瓦で構成される組積造壁と, 凹凸のある煉瓦で構成される組積造壁の斜め圧縮試験を実施して, 破壊性状を調べるとともに, 煉瓦同士の噛み合いによる耐力向上効果について検証した. その結果, 凹凸のある煉瓦で構成される組積造壁の方が最大荷重が小さくなり, 耐力向上効果を確認できなかった. 有限要素解析によって斜め圧縮試験を再現し, 破壊メカニズムを分析した結果, 凹凸のある煉瓦で構成される組積造壁では, 煉瓦同士の噛み合い部に応力集中が生じるため, 煉瓦内部に破壊が生じて直方体煉瓦で構成される組積造壁よりも耐力が小さくなったことがわかった
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