Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE))
Online ISSN : 2185-4653
ISSN-L : 2185-4653
Volume 77 , Issue 4
Showing 1-50 articles out of 63 articles from the selected issue
JSCE Journal of Earthquake Engineering, Vol.40 (Paper)
  • Hiroki KASHIYAMA, Qian CHENG, Miguel B. BRITO, Naomitsu ISHIGAKI, Mits ...
    2021 Volume 77 Issue 4 Pages I_1-I_13
    Published: 2021
    Released: July 22, 2021
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     To ensure the seismic resilience of bridges with a low-cost solution, a novel friction isolation system has been developed based on the traditional friction pendulum system. The proposed system possesses a spherical flat-inclined concrete surface with the aid of three-dimensional (3D) printer. Concrete surface was lubricated with resin material to prevent abrasion from multiple-input ground motions. In this study, size effect on the dynamic behavior of the proposed bridge under bidirectional ground motion was investigated by shaking table test. Experimental results demonstrate that independent of specimen size, response acceleration reduction and small residual displacement could be observed due to the combination of flat and inclined shapes. In addition, simplified method to estimate seismic demand (i.e. maximum response displacement and residual displacement) of proposed system was presented.

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  • Hidetaka SAOMOTO
    2021 Volume 77 Issue 4 Pages I_14-I_23
    Published: 2021
    Released: July 22, 2021
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     The prediction of surface ruptures during an earthquake is important to consider the hazard assessment on the social infrastructure. Two strike-slip faults sometimes produce a pull-apart structure in the region sandwiched by the faults, resulting in a subsidence field. Although there are individual case reports on pull-apart structures, the fundamental mechanism and features of the pull-apart structure are still unclear. Using the finite element method, I thus conducted a parametric study (715 cases in total) by changing tectonic stress setting, step-over distance, and overlap of faults to reveal the relationship between the above parameters and the magnitude of subsidence in the pull-apart structure. The notable results are: (1) An extremely large overlap cannot produce intense subsidence irrespective of the magnitude of step-over, (2) The direction of principal stress affects the magnitude of the subsidence, but it does not affect the displacement pattern of the ground surface, (3) The sensitivity of overlap to the subsidence is larger than that of the step-over to the subsidence, and (4) The NSGA-II optimization algorithm successfully detects each tectonic setting: one for subsidence maximization and the other for the strike components maximization.

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  • Takeshi KOIKE, Taku WATANABE, Maahiro HAMANO, Nobuhiro HASEGAWA, Hirom ...
    2021 Volume 77 Issue 4 Pages I_24-I_34
    Published: 2021
    Released: July 22, 2021
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     Many above-ground water reservoirs constructed more than 50 years ago are deteriorated and always threatened for seismic risk. There are not any conventional method to assess the seismic safety of above-ground water reservoirs. Proposed method includes a new performance-based seismic assessment based on Level 2 reliability formulation which is appropriate with world standard rules requested from WTO. A numerical sample is given how to assess the seismic safety of the reservoir which is modeled to be one-degree-of-freedom vibration system to be simplified from the symmetry of a 3D model.

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  • Toru OKUMURA
    2021 Volume 77 Issue 4 Pages I_35-I_46
    Published: 2021
    Released: July 22, 2021
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     The mechanical behavior of the fixing bolts of the rubber bearings in continuous elevated girder bridges under seismic loading was investigated based on the advanced FE analysis. The detailed FE model of the rubber bearings with the hyperelastic material constitutive model applied to the rubber layers were given realistic boundary conditions considering the behavior of the superstructures and the piers under seismic loading. From this investigation, it was shown that the bending moments around the transverse bridge axis of the rubber bearings greatly affected by the shear deformations and vertical loads. Based on the results of FE analyses, the validity of the calculation method of the stress of the fix-ing bolts used in the conventional design was investigated. Furthermore, the effect of improving the safety of the bolts by introducing the initial tensile axial force into the fixing bolts was examined.

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  • Kazunori WADA, Kimitoshi SAKAI
    2021 Volume 77 Issue 4 Pages I_47-I_60
    Published: 2021
    Released: July 22, 2021
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     We proposed a method to easily and properly evaluate the probability distribution of seismic nonlinear response according to the probability distribution of vibration characteristics such as equivalent natural period and yield seismic intensity of a structure. In the method, the nonlinear response spectrum for a certain earthquake is simply estimated, and the cumulative distribution function of the max ductility ratio is calculated by multiplying the spectrum by the probability distribution of vibration characteristics. The method explicitly considers the difference in nonlinear response to the difference in vibration characteristics. Therefore, compared with the conventional method, the probability distribution of the seismic response can be stably evaluated even in various earthquake motions with different amplitude and periodic characteristics. In addition, since many calculations such as Monte Carlo simulation are not required, it can be expected to be applied to damage assessment during earthquakes for many civil engineering structure groups.

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  • Masaru KITAHARA, Matteo BROGGI, Michael BEER
    2021 Volume 77 Issue 4 Pages I_61-I_70
    Published: 2021
    Released: July 22, 2021
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     The deterioration and damage in seismic-isolation bearings may lead to decreasing the seismic performance of the whole bridge system. Hence evaluating the residual seismic performance of seismic-isolated bridges after a huge earthquake is important to decide their management policy. In this study, an approximate likelihood function is constructed based on the approximate Bayesian computation method. Moreover, an efficient Bayesian inference algorithm combining BUS and the adaptive Kriging model is proposed. The proposed procedure is demonstrated upon a model updating example using a seismic-isolated bridge with deteriorated bearings, revealing that the proposed procedure is capable to obtain reasonable posterior distributions of structural parameters, including the post-yield stiffness of the bearings, with the significantly reduced computational burden. Finally, a residual seismic performance evaluation was conducted by incremental dynamic analysis using the updated model.

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  • Yu YAMAMURA, Yasuko KUWATA
    2021 Volume 77 Issue 4 Pages I_71-I_78
    Published: 2021
    Released: July 22, 2021
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     In the guideline for seismic design of buried pipes, the characteristics of the ground spring in the pipe axial direction, which represents the dynamic interaction between the pipeline and ground, are important for evaluating the seismic resistance of the buried pipes under the seismic forces. The ground spring characteristic in the pipe axial direction is modeled as a bilinear type in which the slip occurs between the pipe and ground if the shear stress exceeds a certain limit. However, the buried pipe has joints, and the friction in the pipe axial direction includes the friction due to the joint’s overhanging part, but their modeling has not been sufficiently studied. In this study, in order to understand the movement of soil particles around the joint when shear displacement is applied, an shear deformation experiment that the pipe and the soil particles are replaced by a two-dimensional cross section was carried out. The movement of soil particles was visualized and the friction mechanism was clarified microscopically.

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  • Yuma KITAI, Hiroki NODA, Yasuko KUWATA
    2021 Volume 77 Issue 4 Pages I_79-I_87
    Published: 2021
    Released: July 22, 2021
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     Seismic resistance of water supply facility and pipeline is promoted to reduce suspension of water supply by an earthquake. Lightweight welded steel pipes with seismic resistance have been widely used for pipeline attached on the bridge. However, there are problems on securing engineers for the field welding method and maintenance. A connection method with seismic resistance, no risk of water leak and easily connection is expected. This study aims to develop mechanical fittings of steel pipe confirmed with seismic resistance equal to or higher than that of welding joints. It can connect easily and reliably by non-specialist engineers. Design verification and verification test were carried out. The seismic resistance of mechanical fittings of steel pipe equal to or higher than that of welding joints was confirmed.

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  • Hideki OMURO, Yasuko KUWATA, Takashi KURIYAMA
    2021 Volume 77 Issue 4 Pages I_88-I_95
    Published: 2021
    Released: July 22, 2021
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     As a method for evaluating the seismic performance of buried pipelines for fluid transportation such as water supply, industrial water, and agricultural water, response displacement method is applied. In the case of seamless continuous pipelines (integral structure pipelines) such as steel pipes and polyethylene pipes, the ground strain acting in the axial direction of the pipe is compared with the allowable strain of the pipe. The critical performance of the polyethylene pipe was evaluated by cyclic tensile and compression load test. As a result, it was revealed that the vibration safety margin is about 25 to 50 times of the equivalent repetition frequency calculated from the earthquakes observed in the past. In addition, since the PE pipe has a small elastic modulus compared to steel pipe, it is feared that it will be damaged during construction or other works in service. The seismic performance in the case with scratches on pipe was also evaluated. It was also confirmed that the seismic performance did not deteriorate within the allowable range for scratches set based on the long terms water tightness.

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  • Kenji KOSA, Nobuyuki NABESHIMA, Takashi SATO
    2021 Volume 77 Issue 4 Pages I_96-I_106
    Published: 2021
    Released: July 22, 2021
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     The authors conducted a field survey in the affected area of 2018 Sulawesi Earthquake, namely focusing on the damage occurred to the Teluk Palu Bridge in Palu City. To investigate damage mechanism of the Teluk Palu Bridge, we conducted dynamic analysis. From the analysis, we can point out the following five problems were identified regarding this arch bridge: resisting capacity of the arch rib, resisting capacity against the punching shear of the bearing system and design concept about the seating length at the pier. Moreover, it was a long-period type earthquake with a maximum acceleration of 200 Gal and punching shear resistance would be reduced due to bidirectional forces (X direction and Y direction).

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  • Wataru HOTTA, Shunichi SUZUKI, Muneo HORI
    2021 Volume 77 Issue 4 Pages I_107-I_116
    Published: 2021
    Released: July 22, 2021
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     Thick plate elements have been widely used in large scale three-dimensional finite element method analyses for many years. However, the nonlinear constitutive relation for reinforced concrete that couples in-plane and out-of-plane deformation could not be applied to ordinary thick plate elements that treat in-plane and out-of-plane constitutive relation separately. In this paper, the nonlinear thick plate element was formulated using the three-dimensional tensorial concrete constitutive relation. Although it was based on the two-dimensional thick plate element, it showed more precise performance than other thick plate elements by processing the six components of strain and stress in order to maintain consistency with continuum mechanics. The effectiveness of the developed thick plate element was verified by comparing with the solid element and conventional thick plate elements and validated by performing the reproduction analysis of a vibration testing.

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  • Tomohiro CHIDA, Shintaro IWAMOTO, Jyunya NOMOTO, Joon-Ho CHOI, Tomoki ...
    2021 Volume 77 Issue 4 Pages I_117-I_127
    Published: 2021
    Released: July 22, 2021
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     In Kumamoto earthquake in April 2017, two upper steel arch bridges seriously injured at arch ribs due to ground deformation can existed, and it was decided that Daiichi Sirakawa railroad bridge was rebuild due to the ground deformation of only 0.3m. However, the design method for the ground deformation is not yet established in specifications of highway bridges of Japan. Thus in this study, we carried out FE analyses for upper steel arch bridge at the time of ground deformation, and varied equivalent stress occurred at arch ribs and deformation behavior in the whole bridge including arch deck. FE analyses were conducted 25 models considering forced displacement and restraint condition as parameters.

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  • Nobuoto NOJIMA, Taro YOKOYAMA
    2021 Volume 77 Issue 4 Pages I_128-I_138
    Published: 2021
    Released: July 22, 2021
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     Several kinds of intensity measures (IM) can be defined from orthogonal horizontal components of seismic waveforms; they are maximum values of each component (NS, EW), geometric mean (GM), larger value (Larger), rotation-independent measures such as maximum (rot100) and median (rot50) obtained by axial rotation. In this study, mutual relationships among such IM’s were probabilistically evaluated. Using accelerograms recorded by K-NET, the distributions of each IM normalized to corresponding rot50 were represented by kernel density. The ratio of NS and EW to rot50 were newly derived as uniform-Rayleigh compound distribution, and on this basis, those for GM and Larger were derived. Bilinear model was adopted for rot100. Period-dependent distributions for each IM were also derived for absolute acceleration, velocity and displacement response waveforms of SDOF with 5% damping.

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  • Yusuke KANAI, Hitoshi NAKASE, Masayuki TOMITA, Risa YAMADA, Toshio SUE ...
    2021 Volume 77 Issue 4 Pages I_139-I_153
    Published: 2021
    Released: July 22, 2021
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     In general, the very dense ground such as diluvial sand was not examined for the liquefaction potential. However, due to the increase of maximum acceleration in seismic design force, the seismic evaluation of the hard diluvial sand is sometimes required for the design of important structures. It has been confirmed that the frozen sample of the diluvial sand has different liquefaction characteristics from liquefiable sand material in laboratory tests. Under undrained cyclic shear loading, the shear strain increases. On the other hand the excess pore water pressure does not increase very much sometimes. This characteristics is considered to be due in part to the solidification force between soil particles, called the aging effects. In this study, to understand the liquefaction characteristics of the solidified sand that is a model of the hard diluvial sand, we conducted liquefaction strength tests of cement mixed specimens. In addition, the analysis by the distinct element method is used to simulate the shear plane development. As a result, it was found that the shear strain increases when the released solidification points are localized.

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  • Shota SUGIURA, Yuta NOGAMI, Katsutomo NIWA, Kohei TANAKA, Kimitoshi SA ...
    2021 Volume 77 Issue 4 Pages I_154-I_163
    Published: 2021
    Released: July 22, 2021
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     In this study, a simplified method for evaluating the amplification factor of surface ground is proposed, which is based on the ratio of the peak period of surface ground to input ground motions, the ratio of the peak value of the ground motion to the strength of surface ground (Ground strength ratio Kf). Three seismic intensities (seismic intensity, SI, and JR-PGA) were selected. The proposed method can take into account the resonance phenomenon between ground motions and surface ground by considering the period ratio as a parameter. In addition, by considering the ratio of strength, the degree of nonlinearity of surface ground can be also considered. It is confirmed that the dispersion of the evaluation results is reduced by taking these parameters into account.

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  • Iwao SUETOMI, Eisuke ISHIDA, Seiji MIZUKAMI, Ken TAMURA
    2021 Volume 77 Issue 4 Pages I_164-I_173
    Published: 2021
    Released: July 22, 2021
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     Tokyo Gas has built a super-dense observation network of about 4, 000 in the Tokyo metropolitan area for safe gas supply. We evaluated the amplification factors of SI value at the observation points, and examined the relation between the topography classification and the average S wave velocity of the surface layer. In this study, the amplification of the response spectrum is calculated by regression analysis and the two parameters, T1: predominant period and Gp: peak amplification factor, are modeled for each topography classification. Then, the database of two parameters with 50m-mesh is calculated and the validity of the proposed model was confirmed by the interpolation estimation using the observed spectra of the 3 earthquakes.

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  • Yoshihiro SHISHIKURA, Yujin YAMAMOTO, Kazuaki WATANABE, Satoshi KOMATS ...
    2021 Volume 77 Issue 4 Pages I_174-I_183
    Published: 2021
    Released: July 22, 2021
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     As a part of the studies on the improvement for seismic performance verification of RC underground structures (box culverts), we conducted horizontal bilateral benchmark experiments on a full-scale RC column member (more than 1 m thick), which are rarely conducted, to obtain basic data for studying the improvement of the accuracy of three-dimensional nonlinear analysis. In this study, a simulation analysis of the benchmark experiment was performed using a generic analysis code. First, a comparison between the experiment and the analysis for the initial loading under repeated loading in horizontal bilateral directions was made to confirm the applicability of the three-dimensional material nonlinear analysis method using discrete bar. And, the effect of the horizontal bilateral loading on the shear fracture behavior of a member was studied numerically using the analytical model that was confirmed to be applicable. Also, the three-dimensional propagation and the openings associated with repeated loading were analyzed from the crack generation situation obtained by analysis.

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  • Yong YANG, Shunsuke TANIMOTO, Takaharu KIRIYAMA
    2021 Volume 77 Issue 4 Pages I_184-I_195
    Published: 2021
    Released: July 22, 2021
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     In this study, dynamic centrifuge model tests were carried out to investigate the seismic retrofitting effect for existing bridge abutment pile foundations in liquefied ground with large thickness. The seismic retrofit of bridge abutment was designed with three different methods. It was confirmed that when the steel pile wall was constructed at the front side of the existing bridge abutment, the lateral flow of liquefied ground as well as the earth pressure on piles was effectively suppressed and thus, the abutment displacement, rotation and the pile bending moment were significantly reduced. On the other hand, when the battered steel pile or the steel pile wall was constructed at the two sides of existing bridge abutment, due to the large earth pressure of the liquefied layer with large thickness, the abutment displacement and rotation could not be effectively restrained and the large bending moment occurred on piles, showing the limited retrofit effect.

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  • Satoshi TAKISAWA, Showta NOMOTO, Keita ABE, Susumu NAKAJIMA, Tsutomu T ...
    2021 Volume 77 Issue 4 Pages I_196-I_206
    Published: 2021
    Released: July 22, 2021
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     In past major earthquakes such as The 2011 off the Pacific coast of Tohoku Earthquake, the masonry train platform collapsed and underwent large deformation. Therefore, we consider that the masonry train platform needs to be reinforced to increase seismic performance, and we are developing an efficient seismic reinforced method. On the other hand, we have not understood seismic performance for masonry train platform with automatic platform gate yet. Therefore, we conducted a shaking table test of the model in a 1G filed in order to investigate the seismic performance of the masonry train platform with automatic platform gate. As a result from the experiment, it was confirmed that the seismic performance of the platform with up the automatic platform gate than one without the automatic platform gate. In addition, a simple reinforcement method was proposed based on the behavior observed in the model experiment. As a result from experiments from the proposed method, improvement of seismic performance by reinforcement was confirmed.

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  • Yasuko KUWATA, Hiromi SAKURAI
    2021 Volume 77 Issue 4 Pages I_207-I_214
    Published: 2021
    Released: July 22, 2021
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     Referring from the case where several pipes with large diameter had damaged with cracks by the earthquake in northern Osaka in 2018, it is considered that not only factors such as insufficient strength and deterioration but also that the pipes with larger diameters is more vulnerable than those with small diameters for the seismic resistance in the transverse direction, which is a so-called size effect. In this study, the more accurate calculation method using soil-and-pipe FEM model and giving inertial force without using soil spring. The influence of the diameter on the seismic response for water pipes with small to large diameters are made clarified. Furthermore, the seismic resistance was compared under various conditions with regard to the damage factor of the 900 mm diameter pipe during the last earthquake. As a result, it was found that the reduction in pipe thickness due to corrosion deterioration contributes more as a damage factor than the increase in hydraulic pressure during the earthquake.

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  • Yukio SHIBA
    2021 Volume 77 Issue 4 Pages I_215-I_228
    Published: 2021
    Released: July 22, 2021
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     The author has been studying on the analytical model and calculation method for use of seismic design for underground vertical shaft structures, and improved the current and popular “beam-and-spring model”, and verified practical performances of the new method. One of the most difficult problems remained for completing the method is adequate modeling of “ground-spring”, mechanical part substituting sophisticated dynamic soil-structure interaction.

     In this paper, a new analytical model, “3D-soil-and-beam model” is discussed for the purpose to find a way out of the “ground-spring” problem. This analytical model is composed of a vertical beam which substitutes the behavior of the underground shaft body, and 3D-FEM solid elements around the beam which is built-up with solid elements of FEM and acts as “ground-spring”. The nodes of the beam and the nodes of the surrounding soil ground are mechanically connected by numerical binding condition of “rigid-beam”. Seismic calculation with this analytical model is done in the way of dynamic response analysis or static technique like the GRAMBS (Ground Response Acceleration Method for Buried Structures). A several examples of calculation with use of this new method are illustrated in this paper, and good performances and utility of the method is shown.

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  • Koichi MORIMOTO, Masakatsu MIYAJIMA, Masato IMAGAWA
    2021 Volume 77 Issue 4 Pages I_229-I_242
    Published: 2021
    Released: July 22, 2021
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     In Japan, earthquake or heavy rain have caused large-scale ground deformation. Therefore, buried water pipelines were damaged seriously. Seismic type ductile iron pipes have not been damaged and have passed water after large-scale ground deformation, because those joints have extension and contraction function, bend performance, and separation preventing performance. But there were few cases that seismic type pipelines were buried at the sites occurring large ground deformations. Ground deformations have been classified by type, such as liquefaction, embankment failure. And different type of countermeasures for ground deformation have been implemented for buried pipes. The pipeline behavior influenced by different type of ground deformation may show similar behavior, because the researches of behavior of pipeline influenced by ground deformations and the test to confirm behavior of pipeline influenced by ground deformations showed that some joints of seismic type pipeline extend, contract, or bend by following ground deformations. However, there are few study cases to compare the ground deformations by using the behavior of seismic type pipeline, without classification by type. In this study, we analyze the behavior of seismic type pipeline influenced by ground deformation, and consider whether it is possible to deal with different type cases of ground deformation as the same classification.

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  • Hiroshi NAKAZAWA, Tomohiro ISHIZAWA, Toru DANJO, Yasuhiro ONOUE
    2021 Volume 77 Issue 4 Pages I_243-I_255
    Published: 2021
    Released: July 22, 2021
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     In recent years, various disasters due to climate change and extreme weather caused by global warming have frequently occurred. On the other hand, there has been recognized many large-scale damages caused by earthquakes. When these are combined, the aspect of the damages becomes even more serious. In this study, both shake table and rainfall sprinkling tests using a simple slope model were carried out in consideration of the combination of rainfall and earthquake. As a result, it was confirmed that the earthquake resistance and the mechanism on slope stability after that differed depending on the previous external factors. In particular, changes in the permeability characteristics and differences in saturation degree due to preceding external factors are considered to be the major factors on occurrence of slope damage.

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  • Koji ITO, Kimitoshi SAKAI, Yoshitaka MURONO
    2021 Volume 77 Issue 4 Pages I_256-I_265
    Published: 2021
    Released: July 22, 2021
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     The damage level of railway structures after earthquakes was judged by the change in eigenvalues of the first-order modes. In this study, we investigated the improvement of this method for the structural integrity assessment. At first, an eigenvalue analysis was carried out by changing the damage location of the structure. From this analysis, the relationship between the location of damage and the change in natural frequencies including higher-order modes was evaluated. In the case of the RC piers, damage to the piers has a significant effect on the first mode natural frequencies. On the other hand, damage to the foundation has a significant effect on the higher mode natural frequencies. In other words, it is possible to identify the location of damage to a structure by understanding the change in natural frequencies of the higher modes.

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  • Keita UEMURA, Kento GOTO, Yoshikazu TAKAHASHI
    2021 Volume 77 Issue 4 Pages I_266-I_283
    Published: 2021
    Released: July 22, 2021
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     In order to realize anti-catastrophe of bridge structures, the structural technology to ensure the performance for beyond design basis events is required. In this study, a concrete hinge structure with a self-centering function and restoring force equivalent of 0.2 G as recovery performance is proposed, and cyclic loading tests are conducted on RC columns with the proposed concrete hinge. As a result, it was confirmed that the proposed concrete hinge achieved a self-centering function and restoring force equivalent to 0.2 G by a steel pipe confining the concrete hinge and an unbonded high-strength rebar placed in the concrete hinge. It was also shown that the restoring force properties of the concrete hinge can be reproduced by the fiber model. When the structure was embedded in RC columns, a large number of shear cracks were observed in the RC columns. However, load decrease wasn’t observed and the function of the concrete hinges inside the RC columns was maintained.

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  • Kimitoshi SAKAI, Akira SUZUKI, Tatsuya DOI, Kenichi KOJIMA
    2021 Volume 77 Issue 4 Pages I_284-I_295
    Published: 2021
    Released: July 22, 2021
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     In this research, a method to efficiently evaluate the seismic performance of railway embankments was proposed. The fundamental characters such as yield seismic intensity were calculated for many railway embankments based on their geometry and soil parameters, and these results were stored in a data-base. When we evaluate the seismic behavior of an embankment, the yield seismic intensity of embankments would be estimated by searching the database using the geometry and soil parameters of embankment. Using the yield seismic intensity from the database, the earthquake displacement is able to calculated, and the damage degree of embankment is judged. The proposed method made it possible to reduce amount of calculations, times and costs, because calculations for estimating seismic parameters of each embankment was not required. The displacement of embankment caused to earthquake given by the proposed method showed good agreement with many design calculations of railway embankments. By using this method, it is possible to evaluate the seismic performance that cannot be judged only by the height or the yield seismic intensity of embankment. This method is effective for the supporting system to determine the priority of seismic reinforcement for railway embankments.

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  • Seiya YAMAKI, Aiko FURUKAWA, Junji KIYONO
    2021 Volume 77 Issue 4 Pages I_296-I_308
    Published: 2021
    Released: July 22, 2021
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     At present, a lot of masonry piers built between Meiji and Taisho era are still in service in Japan. However, it is known that masonry structure is weak to earthquakes. In this paper, the static loading experiment of a masonry pier reinforced by steel plates was firstly simulated by the refined DEM to confirm the validity of the numerical method. The load-displacement relationship before the yielding of the anchor reinforcing bar could be simulated with high accuracy. However, the accuracy after the yielding of the reinforcing bar was low due to the inaccurate modeling of the loading condition. Next, the seismic performance of an existing masonry pier was investigated using the refined DEM. The brick failure and the horizontal displacement at the pier top was observed as the increase of the input acceleration. It was confirmed that the brick failure and the displacement at the pier top can be suppressed by the reinforcement using the steel plates. It was also confirmed that there is a possibility that the reinforced model with hither natural frequency experiences severer failure depending on the frequency characteristics of the input ground motion.

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  • Yoshio SHIOZAKI, Yousuke OHYA, Eiji KOHAMA
    2021 Volume 77 Issue 4 Pages I_309-I_320
    Published: 2021
    Released: July 22, 2021
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     Pile-supported wharves in ports tend to have stringent design conditions due to increased loads and seismic forces. Therefore, even if high-strength steel pipe piles with yield stress of 450 MPa are used, the design may not be easily established. This paper has examined the application of steel pipe pile with yield stress over 450 MPa in port structures. The results are as follows. 1) Cyclic loading experiments of steel pipe pile have been carried out. It has been confirm that the strength and deformation performance were as expected. 2) FEM analysis have revealed that the design method of the bending moment-curvature relationship and the ultimate curvature for yield stress up to 450 MPa is also applicable up to 700 MPa.

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  • Isamu NISHIMURA, Tatsuya NOGUCHI, Takao KAGAWA
    2021 Volume 77 Issue 4 Pages I_321-I_336
    Published: 2021
    Released: July 22, 2021
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     On October 21, 2016, an earthquake with MJMA 6.6 occurred in the central part of Tottori Prefecture, Japan. Observed JMA seismic intensities were 6 lower at Kurayoshi city, Yurihama and Hokuei towns. Housing damages due to the earthquake were concentrated in limited areas. In this study, we carried out microtremor observations around damaged areas, and estimated velocity structures and ground motion characteristics including previously conducted studies. We confirmed relationship between ground motion characteristics and damages due to the earthquake. Low-velocity layers with S-wave velocity less than 200 m/s were estimated at all observation sites and the layers tend to be thicker to coastal plain and thinner to inland areas. Thicknesses to deeper layers with S-wave velocity more than 700 m/s were different in west and east of Hokuei town from earthquake ground motion data. However, estimated ground responses with one-dimensional velocity structures do not match well with the observed damages in the target area. The damages mainly occurred in the area where sedimentary layer thickness changes drastically, and it is suggested that two-dimensional or three-dimensional irregularity of subsurface structure affects much on the damages.

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  • Ibuki AYASHIRO, Keita UEMURA, Yoshikazu TAKAHASHI
    2021 Volume 77 Issue 4 Pages I_337-I_347
    Published: 2021
    Released: July 22, 2021
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     In this study, the dynamic stability of nonlinear single-degree-of-freedom systems with the movement of oscillation center axis (drift) is theoretically and analytically investigated to understand basic dynamic response characteristics of structures in the region of reduced restoring force. Specifically, The response magnification factor of the drift to forced frequency is derived and validated by numerical analysis. As a result, the theoretical value calculated from the response magnification factor was reproduced by the analysis. In addition, it was confirmed that the response diverges to one side rapidly at the singularity on the drift-frequency relation derived from the response magnification factor. Thereby it was suggested that the amount of drift on the singularity may be an important indicator for the dynamic stability of structure systems.

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  • Koki NISHINE, Keita UEMURA, Yoshikazu TAKAHASHI
    2021 Volume 77 Issue 4 Pages I_348-I_359
    Published: 2021
    Released: July 22, 2021
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     In order to realize anti-catastrophe of bridge structures, the structural technology to secure human life and improve the recoverability is required. In this study, a RC column with an embedded concrete filled steel tube with dead weight support capacity was proposed, and its performance was evaluated by cyclic loading tests. In the proposed structure, the embedded concrete filled steel tube was placed so that the bottom of the steel tube and the top of the footing were aligned. As a result, it was possible to prevent the tensile force from being transmitted to the embedded concrete filled steel tube and reduce damage to it. It was also found that the proposed structure exhibits restoring force characteristics and ultimate modes similar to those of ordinary RC columns. After the experiment, the longitudinal bars and the concrete surrounding the embedded concrete filled steel tube were removed. From the results, it was confirmed that the acting axial load could be supported only by the remaining concrete filled steel tube.

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  • Michio OHSUMI, Hisashi NAKAO, Satoshi ISHIZAKI, Gaku SHOJI
    2021 Volume 77 Issue 4 Pages I_360-I_372
    Published: 2021
    Released: July 22, 2021
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     Considering the possibility of occurrence of earthquake motion exceeding the design earthquake motion, we developed a collapse scenario design method. It realize the seismic performance that has been ensured through the conventional seismic design of road bridges, and the function is kept as much as possible, or the function can be recovered quickly against excess motion. In this method, we can select a more desirable scenario by showing the damage mode of the bridge according to excess motion level. We showed how to realize the design of the bridge against the maximum seismic motion by controlling the rupture likelihood after considering the various strengths of the structural elements of the bridge.

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  • Kimitoshi SAKAI, Hoshito MATSUMOTO
    2021 Volume 77 Issue 4 Pages I_373-I_383
    Published: 2021
    Released: July 22, 2021
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     In this paper, a new method to carry out rapid damage estimation of the railway bridges and viaducts was proposed. The proposed method made it possible to estimates the damage occurrence probability of each structure immediately after an earthquake, by improving the nomograph used for seismic damage estimation. The proposed method is more reliable over the conventional method since it reflects the resonance of structure and earthquake by considering the ratio of the dominant period of seismic motions to the intrinsic period of the structures. In addition, proposed method explicitly considers the differences in the yield strength and deformation performance of each structure, depending on the year of construction and the seismic retrofit records. It follows that resulting damage estimation given by the developed method would be applicable for decision-making with regard to resuming train operation after earthquake.

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  • Tanto MASAKI, Hisakazu SAKAI, Yoshio KAJITANI
    2021 Volume 77 Issue 4 Pages I_384-I_393
    Published: 2021
    Released: July 22, 2021
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     In Japan, slope disasters occur on an almost annual basis because there are many mountainous areas in which torrential rains and earthquakes act as triggers. In addition to direct damage to buildings in the immediate vicinity, slope disasters also cause secondary disasters: cutting off areas due to the disruption of infrastructure. To mitigate the damage caused by slope disasters, it is important that measures addressing dangerous slopes be adopted before the disaster occurs. This study combines data from multiple sources, including the slope charts managed by the Niigata Prefecture where the Mid Niigata prefecture Earthquake in 2004 and the Niigataken Chuetsu-oki Earthquake in 2007 occurred, the earthquake motion intensity index data, precipitation amount data, geological maps, soil maps, vegetation maps, and other spatial information data. From both geological and statistical perspectives, the characteristics of the damage caused by slope collapse are clearly understood. Using the latent variables obtained from the covariance structure analysis of multiple explanatory variables, we created a logistic model with high explanatory power for the observed values of slope failure. We have applied the obtained model to other disasters and clarified that it is necessary to consider the variables to be used, the size of the applicable hazard, and other conditions in order to construct a more general model.

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  • Koto ITO, Masaaki WANI, Seiji SAITO, Shun SUZUKI, Kenjiro TERADA
    2021 Volume 77 Issue 4 Pages I_394-I_405
    Published: 2021
    Released: July 22, 2021
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     In this study, we propose the seismic response analysis method with the scheme of separated multi-scale analysis based on the homogenization method. In order to represent the mechanical behavior of sedimentary layered rock mass, we adopt the von-Mises elasto-plasticity and the orthotropic Hill type elasto-plasticity. Also, to identify the macroscopic material parameters, the numerical material tests with the microscopic constitutive law are conducted. Finally, the validity and applicability of the method is verified by performing seismic response analysis of the virtual rock tunnel and comparing it with the result of seismic response analysis by general nonlinear analysis.

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  • Yuki MAEDA, Yusuke ONO, Rusnardi Rahmat PUTRA
    2021 Volume 77 Issue 4 Pages I_406-I_413
    Published: 2021
    Released: July 22, 2021
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     A M9 class earthquake followed by a massive tsunami is predicted to occur near the Mentawai Islands. Residents in the Mentawai Islands need to reach safety in a short time because the tsunami may reach the island within a few minutes after the earthquake. To reduce the time required for evacuation, motorcycles could be used. Motorcycles are the main means of transportation in the Mentawai Islands. In this study, we developed a multi-agent evacuation simulation model that incorporates the behavior of an evacuee on a motorcycle assisting other evacuees on foot. The developed multi-agent evacuation simulation model was used to conduct a case study of Tuapejat on Sipora, which is the administrative center of the Mentawai Islands.

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  • Hirofumi OYABU, Shuichi FUJIKURA, Kentaro TAKAHASHI, Minh Hai NGUYEN, ...
    2021 Volume 77 Issue 4 Pages I_414-I_423
    Published: 2021
    Released: July 22, 2021
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     Although a laminated rubber bearing has been widely used in many bridges as a seismic isolation bearing in Japan, some laminated rubber bearings were damaged during the major earthquakes in recent years. Therefore, it is important to develop a different type of bearings from the laminated rubber bearings in order not to rely on one type of bearings. Spherical sliding bearings (SSB) have been applied for seismic isolation since the 1990’s in some seismic regions. In this study, to investigate the seismic behavior of a single spherical sliding bearing, a series of shaking table tests for bridge model with single SSBs was carried out for applying the SSB to the bridges in Japan. Especially, the influence of the single SSBs to the substructure was investigated.

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  • Manabu HAYASHI, Keita UEMURA, Yoshikazu TAKAHASHI
    2021 Volume 77 Issue 4 Pages I_424-I_435
    Published: 2021
    Released: July 22, 2021
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     In Japan, which is one of the world’s largest earthquake nations, repair work to restore the seismic performance of bridge piers damaged by the occurrence of a large earthquake and seismic reinforcement work to improve seismic performance along with the revision of the technical standards for seismic design have been carried out. Considering the uncertain phenomenon of earthquakes, it is desirable to develop a metabolic seismic pier structure with metabolic functions that can adapt to future technical standards. In this study, it was verified that seismic performance could be recovered by using precast reinforced concrete for the plastic hinge replacement from the viewpoint of early recovery and labor saving, and by using the embedded joint structure in the horizontal joint.

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  • Karina A. SUJATMIKO, Koji ICHII
    2021 Volume 77 Issue 4 Pages I_436-I_445
    Published: 2021
    Released: July 22, 2021
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     On September 28, 2018, a 7.5 earthquake in Palu, Indonesia, triggered multiple phenomena including liquefaction, landslides, and tsunamis. A video recorded the landslide in Jono-Oge, located near Palu Valley, and was captured by a local citizen from his home, which was carried along by a debris flow. The video shows that the land moved like water, carrying buildings, and trees, whereas some other structures remained. The moving camera raises difficulties in the analysis because it operates with various degrees of movement. However, a velocity estimation is possible by applying two types of camera-angle analysis using non-moving buildings captured on the video as a point of reference. In this case, a red roof house and a steel tower were used. We identified that the camera moved from east to west and started at an elevation of 70 m, located 1000 m from the top of the Jono-Oge landslide at the irrigation canal. At an elevation of 68 m, the landslide velocity was 5.1 m/s and slowed down to 4 m/s after moving 200 m to an elevation of 62 m. This deceleration might correspond to a decrease in the slope inclination, from 3% to a gentler slope of only 1%. This result will be informative for the parameters used in landslides and landslide-induced tsunami simulations.

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  • Hayato NISHIKAWA, Tatsuya NOGUCHI
    2021 Volume 77 Issue 4 Pages I_446-I_456
    Published: 2021
    Released: July 22, 2021
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     In this study, we evaluated the source effects, path effects, and site amplification effects by spectral inversion analysis using the records of the seismic observation sites in and around the epicenter area of the 2018 Hokkaido Eastern Iburi earthquake. Amplification factors for indices of earthquake motion were evaluated from the analysis results of attenuation relation. We also investigated the relationship between ground conditions and site amplification effects, which have not been sufficiently evaluated in previous studies. As a result, the correlation between the average S-wave velocity at the surface layer of 30 m and the site amplification effect was highest around 2 Hz. Regarding the amplification factors for indices of earthquake motion, the peak ground motion velocity was higher than the peak ground motion acceleration. Furthermore, Comparing the theoretical transfer function based on microtremor observation and the site amplification effects for three seismic stations, In K-NET Mukawa, it was clarified that the velocity structure to the layer corresponding to the engineering basement has a great influence on the shape of the site amplification effects.

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  • Masahiro HATTORI, Hideo OHISHI, Masaki NAKAMURA, Kazuya MAGOSHI, Masaa ...
    2021 Volume 77 Issue 4 Pages I_457-I_466
    Published: 2021
    Released: July 22, 2021
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     Earthquake damage simulations in expressway network targeted major earthquakes in the future has been researched in Hanshin Expressway. In this study, 1995 Kobe earthquake was tried to reproduce by using this earthquake damage simulation to verify this simulation accuracy. As a result, the damage dispersion of the actual structures at 1995 Kobe earthquake and this reproduction simulation were coincided. In addition, earthquake damage simulations targeted various epicenter were conducted, such as Nankai Trough earthquake and Uemachi earthquake. It was clarified that this simulation system is possible to evaluate pier damages and the amount of step displacement before earthquakes.

     In this paper, 1995 Kobe earthquake was tried to reproduce by using this earthquake damage simulation to verify this simulation accuracy again. In addition, the study on how to use these simulations in our business was showned.

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  • Hiroki KATO, Nobuoto NOJIMA, Yuyu JIAO
    2021 Volume 77 Issue 4 Pages I_467-I_478
    Published: 2021
    Released: July 22, 2021
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     In a large-scale disaster, comprehensive collection of damage information becomes difficult, therefore, the prospect of recovery process of lifelines is inevitably based on limited information. In this study, fundamental analysis was performed for decreasing processes of electric power outage in order to develop a sequential update model of recovery prediction. Firstly, the decreasing process of electric power supply associated with major disasters in Japan was compared using a mixed exponential distribution model which divides the whole process into short- and long-term effects. Next, the sequential update of the prospect of recovery was performed by applying an exponential function to the trend of recovery process at an arbitrary point of time. On this basis, time required for 80, 90 and 95% recovery of power outages was estimated and compared with the observed values. The results suggest that appropriate setting of time interval for curve fitting to the recovery trend is required for rapid and stable update of prediction.

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  • Shinichiro MORI, Shota SAKO
    2021 Volume 77 Issue 4 Pages I_479-I_489
    Published: 2021
    Released: July 22, 2021
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     Vulnerability assessment of rock slopes is mainly done subjectively and qualitatively by field survey and visual inspection, but an objective and quantitative assessment method has been required. The authors have conducted vibration measurements using running vehicles as the source of vibration, and has been investigating the feasibility of this survey method. In this study, we set up six measuring lines on a rock slope and measured the vibration of a running vehicle both on the slope and on the road surface at each measuring line. As a result, the observed vibrations on the slope were different at each measurement line. One wave group was observed at each point on the road surface, while one or more wave groups were observed on the slope. When the running direction of the vehicle was reversed, the order of the timing of occurrence of multiple wave groups was reversed. It was found that there was a point or were multiple points of vibration generation or a narrow area where waves propagated easily other than the closest point of measurement on the slope. The reproducibility of the Fourier spectral shape of the multiple wave groups of vibration on the slope and the stability of the Fourier spectral ratio of the slope to the road surface were confirmed.

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  • Shinichiro MORI, Takumi KOBAYASHI
    2021 Volume 77 Issue 4 Pages I_490-I_502
    Published: 2021
    Released: July 22, 2021
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     An earthquake (Mj 6.1) occurred in northern Osaka Prefecture on June 18, 2018. Immediately after the earthquake, the Japan Meteorological Agency (JMA) and other organization released the map of estimated seismic intensity distribution, which showed that the estimated intensity is 6-lower on the JMA scale over a wide area of Ibaraki and Takatsuki cities. On the other hand, in these areas, there were many cases of partial damage such as roof damage, but very few completely and partially destroyed houses. The seismic intensity estimated by the tombstone behavior varied from 5 lower to 6 upper in Ibaraki City, but was week as 5 lower or weaker in Takatsuki City. In this paper, we describe the results of dense single-point microtremor measurements carried out to clarify the characteristics of ground vibrations in terms of differences in detailed topography, focusing the area where the tombstone-behavior based seismic intensity varied in Ibaraki City. We clarify that the predominant period of vibration of the ground is approximately 0.1 to 0.2 seconds in the area where the tombstone seismic intensity is 6 upper, approximately 0.07 to 0.1 seconds in the area where the tombstone intensity was 6 lower, and equal to or longer than 0.2 seconds in the areas where the tombstone intensity was 5 upper or weaker.

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  • Peilun SHAO, Gakuho WATANABE, Kenji KOSA
    2021 Volume 77 Issue 4 Pages I_503-I_518
    Published: 2021
    Released: July 22, 2021
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     The bending behavior of the reinforced concrete column structure is governed by the pull-out behavior of axial reinforcement. In this study, we performed a cyclic loading test of a reinforced concrete column and investigated the step history, distribution of the strain of axial rebars, and the damage of the columns in detail. The remarkably asymmetrical damage distribution has been observed in the axial reinforcement at the base of the RC column. And the buckling induced in the axial reinforcements caused the deterioration of the lateral force capacity at the post-peak. To reproduce the above bending behavior, we performed the structural analysis in detail based on the nonlinear finite element analysis. As a result, we found that the appropriate modeling of the bond-slip-strain phenomena between the reinforcement and the concrete can reproduce the bending behavior of the RC column.

     In this paper, we reported the effect of bond-slip characteristics of axial reinforcing bars on the bending behavior of RC column structures.

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  • Taisei MORITA, Mamoru OTSUKA, Hisakazu SAKAI, Yusuke ONO
    2021 Volume 77 Issue 4 Pages I_519-I_532
    Published: 2021
    Released: July 22, 2021
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     Since a masonry stone wall is vulnerable structure to strong earthquake motion, the masonry stone walls and the turrets of the Kumamoto castle have suffered severe damages during the 2016 Kumamoto earthquakes. Although Kumamoto city has been considering some seismic reinforcements for the damaged structures, they have not been able to confirm the effects of the countermeasures yet.

     In this study, we conducted two tests; the repose angle tests of cobblestones and the inclination experiments of brick walls with back-fill cobble stones. We constructed three dimensional Discrete Element Method (DEM) by extending the open source analytical software YADE. We investigated the validation of the methods with polyhedral and some spherical clump models for the above two tests and the past shaking table test for wooden blocks. As the results, all of the three tests were accurately reproduced by the numerical analyses, and we confirmed the validation of analytical method with the clump models.

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  • Takaki MATSUMARU, Toshiyasu UNNO, Yusuke MIDORIKAWA
    2021 Volume 77 Issue 4 Pages I_533-I_543
    Published: 2021
    Released: July 22, 2021
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     In this paper, the numerical simulations were conducted in order to reproduce the tendency obtained in the unsatured liquefaction tests (cyclic tri-axial tests) using volcanic soils (Spfa-1 and En-a) damaged in the 2018 Hokkaido Iburi eastern earthquake. In the numerical simulations, the three-phase porous media theory was applied. However, the simulated results underestimated the unsaturated liquefaction resistance in unsaturated conditions, because the constitutive models used in the simulations were developed for describing the tendency of liquefaction characteristics for saturated soils. Therefore, the evolution rules focused on the change of void ratio were proposed for modifying the dilatancy characteristic of unsaturated soils. The simulated results using proposed method could successfully reproduce the tendency obtained in the tests using both soil.

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  • Ryoh KURAMOTO, Takashi WATANABE, Takeshi YOSHIOKA, Toshiyasu MIYOSHI
    2021 Volume 77 Issue 4 Pages I_544-I_556
    Published: 2021
    Released: July 22, 2021
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     Overturning stability verification of an offshore wind power generator subjected to Level 2 (L2) earthquake, is conventionally evaluated through a static overturning safety factor, which does not consider the dynamic behavior of the system as well as the influence of fluid resistance of seawater. So, there is a possibility of excessive design.

     The current study involves the numerical simulation of a shake table test, performed in previous studies, on an offshore wind generation foundation with gravity-type support structure using the particle method and the discrete element method. The effect of seawater and foundation mound on the wind power generation foundation is examined. From the analysis results, it was confirmed that the effect of seawater fluid resistance on the overturning stability was negligible. On the other hand, it was observed that increasing the seismic wave input level increases the effect of attenuation by the foundation mound layer.

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  • Masataka SHIGA, Takashi KIYOTA, Toshihiko KATAGIRI
    2021 Volume 77 Issue 4 Pages I_557-I_563
    Published: 2021
    Released: July 22, 2021
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     Pleistocene sandy soil are more stabilized in terms of physical and chemical properties than Holocene sandy soil. It is difficult to quantify the effect of the stabilization on liquefaction characteristics, and the conventional liquefaction assessment method has been done within the same framework as conventional sandy soil. In this study, shear wave velocity, which was introduced to quantify soil fabric in previous studies, is applied to the artificially cemented test specimen to investigate the effect on the soil structure. In addition, undrained cyclic loading tests were carried out to discuss the stress path, stress-strain relationship and normalized loss energy.

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JSCE Journal of Earthquake Engineering, Vol.40 (Technical Report)
  • Sumio YANAGIHARA, Masataka NAKAMURA, Yozo GOTO, Miyuki YAMAMOTO, Ryuji ...
    2021 Volume 77 Issue 4 Pages I_564-I_574
    Published: 2021
    Released: July 22, 2021
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     The present study aims to grasp the actual situation of the initial emergency recovery responses of the local construction companies for infrastructure facilities and to extract their issues, immediately after the 2016 Kumamoto Earthquake. The following results were obtained from a set of interview survey and questionnaire on their emergency recovery responses: (1) The disaster agreement should be improved because the delays and the confusions occurred in the initial responses. (2) The supply of the construction resources should be written on the disaster prevention planning etc. because the shorting of necessary resources happened. (3) Although there was no problem in the reimbursement amount for the recovery constructions executed by companies, the processes for the smooth payment and the evidence reporting of construction cost should be improved. (4) The safety training system should be established urgently because the job safety level degraded during the emergency recovery work. (5) For the injured worker in an accident during the emergency recovery, many construction companies hoped to apply equivalent compensation as for an injured public servant case. It is necessary to discuss measures for the compensation system, including legal aspects.

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