A lot of plain concrete piers are used as railway structures at present. At the time of a large earthquake, the horizontal perforated crack or slide along the construction joint and spalls under the construction joint are frequently occurred due to their earthquake-resistant lowness.
 In this study, the behavior, the failure mode, and the validity for plain concrete piers on the static test and the dynamic test with the large seismic device were experimentally investigated using the 1/2.5 scale specimens and the one with the movement restraining devices for the construction joint.
 Test results indicate that the maximum and the residual displacement of the specimen with the movement restraining devices are smaller than the specimen without the devices. Moreover, the behavior of spalls under the construction joint and the range of the load acting on the pier above the construction joint are clarified.

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 Effective stress analyses based on the finite element method are often used as a reliable tool to predict liquefaction occurrence in soil-structure systems during earthquakes. In the analyses, the soil properties are typically specified by using a deterministic model although they intrinsically have spatial variability even in the case of horizontally layered ground. In this study, nonlinear finite element analyses under undrained conditions are performed to investigate the effects of soil heterogeneity on the liquefaction behavior of stochastically heterogeneous soil deposits subjected to seismic loading through a Monte Carlo simulation approach. A series of analyses has revealed that the heterogeneity of the shear wave velocity (or initial shear modulus) has no significant effect on the distribution of the computed excess pore water pressure (EPWP); while the mean value of the maximum EPWP ratio is partially influenced and becomes up to 20% less (in comparison with the deterministic case) by considering the spatial variability in the internal friction angle and the N value under the given seismic loading.

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 Because of a partial loss of area for opening, the shaft having opening secures a necessary shear strength by the residual section exept the opening. In general, the three-dimensional behavior is not considered with the structure around the opening, that may be not rational. Therefore, we checked the effect on the shear strength of the shaft by three-dimensional FEM analysis to simulate the concrete and the reinforcing bar. And also, we confirmed the influence of the thickness, the concrete strength, the quantity of the distributing bar and the layout of the opening, that have a large influence on the shear strength of the shaft. As a result, we confirmed that we might be able to evaluate the shear strength of the shaft having opening with a simple numerical expression.

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 The purpose of this research aims to develop a cost-effective sheet-pile quay wall with high seismic performance by applying reinforced earth method which has been widely used in land construction works. In the past, authors have already conducted a centrifuge test using geogrid reinforcement under 50g and confirmed its high seismic performance by evaluating the reduction in lateral displacement and bending moment of sheet pile. In this paper, using non-linear elastic-plastic analysis towards past centrifuge test is first conducted, and a series of parametric study by changing length, height, and number of geogrid reinforcement are made to clarify the mechanism. The results showed that friction force act on the geogrid which is proportional to the effective normal stress countervails the earth pressure during shaking, and enough length of geogrid reinforcement is necessary to excess the distance between sheet-pile and active collapse angle curve. Further, length of the bottom geogrid reinforcement contributes most to the overall stability.

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 In the 2016 Kumamoto Earthquake, two severe ground shakings occurred consecutively on April 14 and 16, and caused extensive damage to bridges. Among them, it should be paid strong attention that numerous lateral displacement confining devices were suffered sever damage. Their function was to constrain a superstructure from developing displacement if a bearing support is destroyed and to prevent collapse of the superstructure. However, brittle damages were observed in the devices themselves or the anchorage portions, and one bridge was collapsed due to the mainshock because the device had been damaged due to the foreshock. In this paper, the seismic analysis of the collapse bridge was conducted to estimate the pounding force to the device, and the failure mechanism of the device was estimated.

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 To reliably predict surface rupture around the active fault, we need to compile much knowledge such as fault plane shape, subsurface structure, regional stress field, geo-material properties, and the scaling law represented by Matsuda's equation. This paper presents a basic scheme to incorporate those knowledge into the finite element analysis, especially focusing on the treatment of Matsuda's equation. After the scheme introduction, I performed a case study of displacement assessment on the Uemachi fault system in the Osaka basin and then compared the simulated displacement with that obtained from borehole drilling survey. This comparison showed that the simulated displacement (1.51 m) was almost in good agreement with the field survey result (1.6 m – 2.4 m). In addition, the simulation revealed the severe regional stress condition having ESE-WNW orientation of compressional axis which maximizes the displacement on most fault planes in and around the Osaka basin. Also, the simulation disclosed the interaction effect between the Uemachi fault segments and other fault planes. These results provide new insight in terms of the robust design of infrastructures upon surface rupture assessment.

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 According to the analysis of seismic observation records, the site characteristics of strong motions at engineering base layer in Kanto region show the regionality. We have been conducted numerical simulation analyses to understand the reason of this phenomenon. Our tentative view of the reason is due to the amplification effects generated by the deep ground structure. In this study, the validity of 3D FEM numerical simulation was investigated with comparing the calculated results to the observation record. At the same time, parametric study was carried out in order to obtain the optimum source model. Then, the correction of calculated ground motion with respect to distance attenuation was performed to examine the quantitative spatial characteristic of simulation results. The attenuation relation model of ground motions at engineering base layer was developed by using the observation records in the target area. Quantitative investigation with respect to the mechanism to produce the regional site effects on seismic ground motion at engineering base layer in Kanto region was implemented by the process mentioned above.

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 This paper forms a part of a comprehensive study on developing a high-performance seismic damper termed Buckling Restrained Rippled Plate (BRRP) damper. In order to increase the load carrying capacity and to fulfill compactness of existing BRRPs, a new type of BRRP seismic dampers are proposed in which a set of two parallel core rippled plates are utilized to form a single BRRP named Twin-BRRP. To examine the deformation and low-cycle fatigue performances of Twin-BRRPs cyclic loading tests and analyses with variable and constant amplitudes have been performed. Furthermore the pushover behavior of the restraining members after the core plate having contacted are examined through tests and analysis.

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 In this study, in order to investigate the effect of overburden depth on the reduction effect of sectional force of piers founded deep in the ground by using isolation bearings, we conducted dynamic analysis considering overburden depth, bearing structure as a parameter and evaluated the response plasticity rate and the degree of shear allowance of the body. As a result, under the analysis conditions of this study, the sectional forces of the body are effectively reduced by the isolation bearings when the overburden depth is less than about half of the height of the pier. On the other hand, when the most of body is buried in the ground, the effect of reducing the sectional force by using the isolation bearings decreases due to both the increase of the kinematic interaction effect caused by the large overburden depth and the decrease of the inertial interaction effect caused by the decrease of the ground surface acceleration.

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 For probabilistic seismic hazard maps produced by the Headquarters for Earthquake Research Promotion, the comprehensive database of earthquake occurrence models in and around Japan is compiled and provided via the website of the Japan Seismic Hazard Information Station (J-SHIS). Taking advantage of the database, this study evaluates the relationship between population exposure to five ranks of JMA (Japan Meteorological Agency) seismic intensity scale and the probability of occurrence of earthquakes within 30 years ("P-PEX relation") for all the potential events of earthquake. On this basis, seismic risk curves and expected population exposure are assesses for the period of 30 years. Finally, as an extended application, risk assessment of disruption of utility lifelines are performed for electric power, water and city gas supply focusing on four kinds of duration of disruption: immediately, three days, one week and one month after the earthquake.

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 A method to evaluate the system reliability of road networks during a catastrophic tsunami disaster was newly proposed based on physical tsunami damage functions of roads and bridges, which were derived by assessment for damage data in the 2011 off the Pacific coast of Tohoku earthquake tsunami. In the framework, the features of shortest routes between targeted substantial public facilities in a tsunami disaster are identified by using Dijkstra Algorism. In addition, the features of routes between them preferentially passing through main roads are identified. Finally, vulnerable roads and bridges on which tsunami countermeasures should be taken and which should be restored preferentially are revealed. This proposed framework was applied to the case studies for road networks in Tokushima city, which is expected to be suffered greatly from the anticipated Nankai Trough earthquake tsunami, and the possibility of road disruption in a tsunami disaster was also investigated.

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 After the 1995 Kobe earthquake, the structural performance concept of a bridge in Japan considers two levels of seismic excitation which are named as Level 1 and Level 2. However, the Level 2 of ground motion input is a large seismic coefficient demand. Also, the problem of bridge rubber bearing support which commonly is used in Japan lost expected seismic performance due to the deterioration. Some possible causes of the deterioration are the aging, the compression fatigue, or the frequent lateral deformation which triggered by traffic load, wind load, thermal expansion, creeps, and shrinkages phenomena of daily load. While the behavior and the parameters of reinforced concrete (RC) column accompanied with friction device were determined successfully based on the experiment and numerical analysis. This study proposed the structural system of integrated bridge pier with triple RC column connected by friction damper plus gap which is expected to substitute the conventional bridge pier system avoiding the use of rubber bearing. In the investigation of its behavior and seismic performance, numerical analysis was performed with fiber cross-section of non-linear beam-column-based element model on the longitudinal direction of the bridge structure. As the analysis result, the proposed structure had an excellent performance not only under small deformation to allocate frequent lateral deformation but also under seismic load. Furthermore, in the structural simulations, the consideration of different limit state of column location and the various yield strength of reinforcing steel configuration can obtain a better structural cost-performance option.

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 Recently, damage due to aging deterioration is observed in aged rubber bearings used in highway bridges. Effect of such deterioration of rubber bearings on the seismic safety of the bridges is of great concern considering uncertainty due to the individual difference of their performance and the level of earthquake ground motions. Countermeasures against the above problem are required to ensure that the safety of the bridge is not impaired on the premise of a range of variations in the involving factors.
 In this study, the effectiveness of application of restraining cables to existing bridges with aged rubber bearings is assessed as a measure to ensure bridge safety against not only level 2 (MCE) earthquakes but also ground motions exceeding the design level. To assess its effectiveness, the Incremental Dynamic Analysis is conducted considering variation in the characteristics of the rubber bearings and cables. The analysis showed that the restraining cable application is effective in reducing the girder displacement, mitigating the possibility of the failure of the bearings and the piers, and reducing variations in the structural response.

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 A new procedure was proposed to estimate incident seismic wave in time domain based on vertical array records. Conventional methods solve a simultaneous equation including the equation of motion for the response of ground above the bedrock and the basic equation for the viscous boundary, where, unlike ordinary forward analyses, the incident wave is output rather than input. In the new method, there equations do not constitute a simultaneous equation anymore; first, the response of the ground is calculated and then the incident wave is estimated based on the basic equation for the viscous boundary. In the new procedure, any program that has been used for the forward analyses can be used for the estimation of the incident wave, without rewriting the source code. As an application of the method, the incident wave was estimated based on the vertical array records at Port Island, Kobe, Japan, during the 1995 Kobe earthquake.

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 In this paper, daily traffic volumes on highway networks damaged in the 2016 Kumamoto Earthquake Disaster were spatiotemporally visualized and analyzed. The network functions of highways in Kumamoto and Oita prefectures were severed immediately after the main shock. Once the traffic restrictions and controls were lifted, traffic volumes got back to normal after mid-May. Next, in order to understand an initial response after an earthquake, trends of restoration and traffic flow, average daily travel speeds were also shown. Moreover, three kinds of highway network performance measures were assessed. Two physical measures describing the number of sections and total distances opened to traffic decreased by approximately 60% to 100% than normal in Kyusyu expressway and Oita expressway, while the functional measure describing traffic volumes decreased by approximately 50% to 80%. Each measure got back to normal within three weeks after the earthquake. Comparison with the past two catastrophic disasters, the Great Hanshin-Awaji Earthquake Disaster and the Great East Japan Earthquake Disaster were made. The functional measures were consistently lower than the physical measures, reaching the pre-quake level after the physical measures completely recovered.

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 The 2016 Kumamoto earthquake caused severe damage of civil infrastructures, including bridges which were constructed after 1995 Kobe Earthquake. The aim of this study is to estimate the failure mechanism of RC hollow bridge columns with rubber bearings. In our field survey, the typical crack pattern of the RC hollow columns and a land slide in the mountain beside the bridge were observed. In order to clarify whether the main factor causing the damage is the strong ground motion or the land slide, static analysis was conducted and the results were compared with the measurement after the earthquake. This research revealed that the main factor is the inertial force acting on the bridge column and it has the possibility to rupture the rubber bearing on the column.

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 In this study, a cyclic torsional shear test using various seismic waveforms observed by the strongmotion seismograph networks, K-NET and KiK-net, was performed. Furthermore, the effect of the waveform and its duration on the liquefaction strength and its characteristics were explored. The test results were analyzed and compared with those obtained using a general sine wave. The used seismic waveforms were typical waveforms of the 2016 Kumamoto earthquake (inland earthquake), and the 2011 Great East Japan Earthquake (subduction earthquake). The weighting factor concerning the irregular nature of seismic wave C₂ exhibited a correlation with the significant wave number. Moreover, it proved that the respective C₂ values of Mashiki main shockwave and the Haramachi wave differed by a factor of 2. The evaluation of the liquefaction strength property with respect to the cumulative dissipation energy showed that the sine wave becomes nearly identical against the difference in the cyclic number. Meanwhile, the test results concerning the seismic waveforms showed that the cumulative dissipation energy among them differed by a factor of 10.

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 Site boundary lines are often drawn in close proximity to the rear side of leaning retaining walls constructed on cut banks along urban rail lines; thus, it is difficult to apply conventional seismic countermeasure methods, where micropilings are inserted perpendicularly into the bank. In this study, methods of seismic countermeasure were developed for leaning-type retaining walls in which micropilings inserted at sharp angles from the rear side of the walls in the area within the site boundary line are linked to the upper part of walls. In order to confirm the reinforcing effect and mechanisms of such a method, shaking table tests were conducted in the gravity field using a 1/10 scale model. Through these tests, it was confirmed that the earthquake resistance improved according to length of the micropilings, with significant deterring effect on overturn displacement. The calculated displacement based on Newmark's method using experimental data was smaller than that observed by experiment.

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 This study estimates the number of floating population using the GPS data collected by smartphones. Because the frequency of data acquisition by mobile apps varies from several tens of seconds to an hour, it was difficult to estimate the number of population only from the recorded locations. Hence, the individual's pathway was obtained based on the function of GIS to find the shortest route following the GPS logging data. This study also considers the relationship between the number of the GPS data obtained by smartphones and that of pedestrians, and a series of regression analyses is performed to develop a numerical model for the estimation of the number of floating population. The results of this study are helpful to consider the countermeasures of a large earthquake in Tokyo Metropolitan area.

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 In seismic design for RC columns, it is necessary to improve ductility and prevent sharp load decrease of RC columns. In this research, the hook with head is suggested to prevent buckling of longitudinal bars, and the advantage effect of the hook with head was examined by cyclic loading tests. As a result, it was more effective for improving load decrease to use the hook with head than to use hoops. However, the hook with head can't resist buckling deformation of longitudinal bars because of opening of the hook after the buckling of longitudinal bar occurs. Therefore, improvement of the hook with head is necessary so as not to open the hook.

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 A method for mode decomposition and synthesis of velocity response spectra has been proposed using Karhunen-Loéve transform (KLT) . Eigenvalues and eigenvectors are solved for correlation matrix of the 101-dimensional feature vectors representing velocity response spectra calculated using a number of accelerograms. Next, the feature vectors are transformed to principal components using the orthogonal matrix composed of the eigenvectors. Several principal components are adopted to recompose the original response spectra without much loss of information. Illustrative examples using acceleration records observed in the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan are shown. Modal synthesis using approximately three to twelve principal modes has been found to effective to recompose original response spectrum for damping ratio 5%. Less number of modes are required for damping ration 20%. It has been found that the orthogonal bases derived from KLT of all the ground motion records from nine major earthquakes can be modeled by simple cosine functions which can be universally used for discrete cosine transform (DCT).

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 The purpose of this study is to reveal the relation between yield strength of structure limiting excessive displacement and the load that shear cracks occur on the abutment. Especially, the relation of design seismic load and damage form are focused on. From the analytical result, stiffness changes radically when the load is 3798kN because reinforcing bar of displacement restriction structure is yield. Secondary, as the seismic load is decrease, the number of the shear cracks increase in the excessive displacement stopper. Finally, it would be necessary to lift up the height of structure limiting excessive displacement in order to damage the structure limiting excessive displacement before the shear cracks occur in the abutment.

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 This study tries to develop a more accurate numerical model to estimate the restoration time of the expressways after an earthquake. The previous model developed by Uehara and Maruyama (2016) underestimated the restoration time after the 2016 Kumamoto earthquake. Hence, the authors performed a series of logistic regression analyses to develop the numerical model for the estimation of the restoration time of the expressways after an earthquake. The authors modified the numerical model to include the effects of road-structural types on the restoration time after the actual earthquakes. The numerical model was applied to a scenario earthquake in the Nankai Trough, and the restoration time was estimated.

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 It has been known that existing bridge abutment in liquefied ground suffered great damage during past earthquakes. Rapid countermeasures become necessary when bridge abutment can't satisfy performance requirements of current standard. In this research, construction methods which can be conducted simultaneously with transportation or with less restriction based on conventional liquefaction countermeasures, ground anchor method and soil improvement method are discussed, and shaking table test is conducted to verify the strengthening effect. The result showed that ground anchor method performed well at restraint towards displacement of bridge abutment. However, additional countermeasures are still needed to be concerned for great settlement of the back ground. For soil improvement method, especially for the case when bridge abutment is enclosed by soil improvement body, proper space need to be established to avoid the risk of adverse effect.

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 In this paper, analytical studies on damage detection of RC viaduct by microtremor observation are conducted. Plastic hinge at the bottom of pier is represented as damage, following three cases are set up, the case of no damage (Case0), the case in which damages occur on one side of bridge axial direction (Case1), the case in which damages occur on one side of bridge axial rectangular direction (Case2). In each case, characteristic vibration mode is estimated by eigenvalue analysis, and dynamic analysis in which two directional microtremor waves are input to the bottom of pier is carried out. The difference of Case0~Case2 is evaluated by comparing transfer functions at representative points. As a result, it is verified that transfer function given from microtremor observation is effective to specify damage area.

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 In April 2016, a series of earthquakes named as the 2016 Kumamoto earthquakes struck at central Kyushu area in the southwest of Japan. During the first and main shocks, large velocity records were obtained at the Mifune interchange on the Kyushu expressway. The records were much larger than observation records in the surrounding area. Our research focuses on studying the generation mechanism of the strong velocity records at the Mifune interchange. In this study, we conduct microtremor observations and estimate shallow S-wave velocity structures at Mifune interchange and two other neighborhood locations. Based on the obtained shallow S-wave velocity structures, the velocity waves at Mifune interchange were simulated for both the first and main shock events. The simulation results agreed well with the observation records. The study found that the site amplification by the shallow subsurface soil layer was one of the reasons causing strong velocities at the Mifune interchange on the Kyushu expressway.

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 An accelerometer, whose sensor adopts a crystal oscillator, can be expected even with higher sensitivity, and smaller and more accurate sensor than a conventional accelerometer which consists of a pendulum. However, the crystal oscillator is strongly affected by fluctuation of temperature. We modify a manufactured product of accelerometer to a kind of oven controlled crystal oscillator (OCXO), and examine its basic performance through two types of observations. A relationship between output values of temperature and acceleration is discussed and modeled using a simple regression expression to correct acceleration with value of temperature. It is found that the accuracy of the modified sensor is less than 3 mGal in root mean square after applying the correction.

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 In this study, geographical data on the road network downloaded from OpenStreetMap and altitude data from the Geographical Survey Foundation Map were used to quantify the possibility of isolation of a village during earthquake in a mountainous area. The possibility of isolation was defined by the probability of disconnection of the road network between a settlement and the local government office in the target area. The probability of failure of nodes and links constituting the road network was evaluated by using the probability of slope failure that was calculated with the equation by Sakai et al. (2013). The disconnected probability of the road network was calculated by the Monte Carlo Method. For the evaluation by the constructed method, the influences of countermeasure works and the difference of the digital elevation model to be used were discussed. Furthermore, the advantages and disadvantages of using OpenStreetMap on the evaluation of isolation possibility of earthquake in the mountainous area were summarized.

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 It is required to determine proper countermeasures of a railway embankment by evaluating failure mode of the embankment that is selected as that assumed to fail during earthquake in order to carry out seismic countermeasures for preventing failure of the embankment. Although a study on selection of the embankment that assumed to fail is performed, it is confirmed that position of slip surface calculated by stability analysis based on the circular slip surface that does not include progressive failure of a soil can be deeper than that obtained from a model experiment. Hence, in this study, numerical study utilizing mesh free method that can deal with the progressive failure and residual deformation of the embankment was performed in order to investigate influence of the progressive failure on the failure mode of the embankment.

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 In this paper, the nonlinear dynamic analysis method of liquefied ground by equivalent single degree of freedom model was proposed. First, time history of the strength change of the whole ground were calculated by using the liquefaction strength curve of whole ground and cumulative damage rule. Second, by introducing this strength change into the equivalent single degree of freedom model, it is possible to easily calculate the ground response directly considering its nonlinear behaviors such as strength reduction and elongation of natural period due to liquefaction. It was verified through numerical simulations that the ground response evaluated using the proposed method generally agreed with that obtained by the effective stress analysis method. The proposed method is advantageous over other methods that only three parameters are necessary for calculation; natural period of ground, the strength of whole ground and the strength change curve of ground. These parameters can be easily evaluated from the soil boring log. The proposed method is effective as a simple evaluation method of earthquake motion in liquefied ground.

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 In this study, a series of shaking table test of an abutment model with 1.0 m high that was designed as a 1/8 scale model of a gravity abutment with 8.0 m high was performed using L1 and L2 seismic waves and 3.0 Hz sine waves that were incrementally increased step by step in order to investigate mechanism of generation of seismic earth pressure interacting on the abutment. Behavior of the abutment model and a backfill soil during shaking was analyzed by an image analysis tracing displacement of markers installed on the model and soil using a high speed camera. It was confirmed that the generation of seismic earth pressure was influenced by small relative displacement between the abutment model and backfill soil as well as response acceleration of the backfill soil as a result from the shaking table test. Also, it was found out that relationship between the seismic earth pressure, inertial force of the backfill soil, and the relative displacement between the abutment model and backfill soil was different depending on height of the abutment model and influenced by the behavior of the abutment model and backfill soil.

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 Siphon pipe is a crucial structure as a part of trunk line for water supply. Since the channel slope is high, the seismic evaluation for the direction of crossing as well as for the direction of running is necessary. However, most of the existing siphon pipes were constructed before establishing of calculation method of seismic design. The studies on seismic performance of siphon pipe have been done few. In this study, the check method of seismic performance for siphon pipe was set and the problems on seismic performance was made clear based on this check method throughout the parametric studies of dynamic analysis. In addition, the priority index on selecting the siphon among several ones was proposed as the first stage of the seismic performance check. As the results, the check to the bending moment is considered as an indicator of determining the priority on seismic evaluation. It was shown that the channel slopes strongly affected seismic performance in the direction of running.

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 Response displacement method have been used for evaluating seismic response values of bridge, viaducts and underground structures. At this time, it is necessary to evaluate ground displacement as seismic action and it is evaluated from the natural period of surface ground which is calculated from the initial stiffness of each soil layer. However, in case of inputting the strong ground motion, the nonlinearity of surface ground has a large effect on ground displacement.
 Therefore, in this study, we propose an evaluation method of ground displacement considering the shear strength of surface ground, which is called ground strength ratio K_f, for the improvement of the conventional method. K_f can be easily estimated from the information of general soil surveys. So, this method is considered to be effective method as an evaluation method of ground displacement for applying response displacement method.

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 This study evaluated the topographic characteristics at the landslide outbreak locations based on the covariance structure analysis and the machine learnings. The support vector machine (SVM) and random forest (RF) were employed in this study to achieve the objective. The estimated results were compared to investigate the accuracy of the detection of landslide occurrences. The SVM and RF gave reasonable results if a technique for oversampling is applied to correct for a bias in the training dataset. Lastly, the discriminated results were projected onto a map to evaluate the possibility of landslide occurrences.

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 Although more than a year has passed since Kumamoto earthquake in April 2017, the reason of the collapse of Asooohashi has not yet been cleared. Initially, while it was thought that Asooohashi was collapsed by landslide disaster, recently it was also thought by ground deformation around the arch abutment of Asooohashi. However, neither of them has been clearly verified.
 In this study, FEM analyses were carried out focusing on the ground deformation due to a few fault raptures and mudflows due to landslide disaster to estimate the cause of the collapse of Asooohashi. With regard to the ground deformation, the amount of ground displacement was measured by an aerosurvey. And it was found that the relative displacement between the right bank and the left bank was 2.24m in the longitudinal direction of the bridge and 0.68m in the transverse direction of the bridge. FEM analyses were conducted based on these values, and markedly high equivalent stress was occurred in the entire arch ribs. Therefore it is shown that the possibility that Asooohashi collapsed by ground deformation was extremely high. With regard to the mudflow, FEM analyses were conducted on the assumption that the mudflow with 1m or 2m reached 1/2 or 1/4 arch span. And it was found that the possibility that Asooohashi collapsed by the mudflow was small.

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 Recently, significant damage of underground structures due to the fault rapture displacement was reported. Many researchers focus on the force induced by fault rapture displacement based on analytical and experimental studies. However, the study on damage of underground structures subjected to the fault is insufficient. This study clarifies failure mechanism of RC box culvert subjected to the fault rapture displacement based on 2D Finite Element analysis with three parameters of structure depth; 20m, 10m and 5m from the top slab. Based on the analytical results, it is found that shear force acted in side walls due to fault rapture displacement depends on the depth of structures and results in failure mechanism; the side wall in deeper RC box culvert with depth of 20m collapses in diagonal shear due to large soil pressure, while the shallow RC box culvert with depth of 5-10m failed in slip shear at the bottom of a side wall.

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 This paper presents the result on estimation of ground motion at Mashiki Town in Kumamoto prefecture where the strong ground motion hit and many infrastructures were damaged at the time of the 2016 Kumamoto Earthquake. Focusing on relative displacement and conduits damage, the relationship of them are analyzed. Using the SDOF model of surface layer based on the data from microtremor measurement, strong ground motions are simulated so as to evaluate relative displacement. Large velocity and relative displacement affect on conduits damage from the calculation results.

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 An earthquake of M_JMA 6.6 occurred in the central part of Tottori prefecture in Japan on October 21, 2016. Recorded JMA seismic intensity were 6 lower at three observation points. Serious damages were concentrated in partial areas. Aftershock observations were conducted at damaged area to clarify causes of the damage. In this study, we evaluated strong ground motions at aftershock observations points using empirical Green's function method. It was found that damaged sites tend to have high peak ground velocity and high response values in period range around 1.0sec.

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 This study performed a series of driving simulator experiments to investigate an effective way to transmit evacuation information to drivers in case of tsunami. The traffic information was transmitted through a car navigation system, and eye movements were recorded during an experiment. The 28 examinees were employed for the three types of experiments, and the results were compared to reveal the effective way to transmit the information to the drives. According to the results of the experiments, the information of traffic congestion is not sufficient to improve the evacuation rate. However, hazard map is an effective tool to notice the tsunami-inundated area to the drivers.

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 In Nepal, Many gabion retaining walls for road were damaged after 2015 Nepal Gorkha earthquake. In this study, a full-scale model experiment was conducted to estimate an earthquake behavior and a residual deformation of an erect triple layer placing gabion retaining wall which is 3m high as typical gabion structures seen there. A full-scale model was constructed by packing round stone materials into gabions and filling Masado soil behind the retaining wall in a large soil container. After construction, 4 times shaking tests were conducted and, an expansion of collapsed back fill due to dynamic behavior of the retaining wall was confirmed. According to the measurements of residual deformations, a large inclination of the retaining wall and horizontal displacement of about 80cm at the crest are confirmed. As a result, it was found that the gabion retaining wall is relatively flexible, but it doesn't lead to catastrophic destruction.

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 The purpose of this research was to discuss the un-differentiable features hidden in observed earthquake acceleration records. On the assumption that the Fourier transformations of acceleration time history, such as the real and imaginary parts as well as the amplitude and phase, are continuous stochastic process with respect to (wrt) the circular frequency, we investigated their stochastic characteristics such as the mean square sum and the distribution feature. We found that probability distribution functions of the first derivative of real and imaginary parts of the Fourier transform of acceleration time history wrt the circular frequency were expressed by the Levy flight distribution with same parameters. This resulted in that the real and imaginary parts were un-differentiable function wrt the circular frequency because the variance of Levy flight distribution could not be defined. Based on this fact we, therefore, suggested a possibility that the jerk (the derivation of acceleration wrt time) of observed acceleration records is a discontinuous functions wrt time.

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 By utilizing ortho images of aerial photographs taken within 3 days after the mainshock of the 2016 Kumamoto earthquake, we classified the damage of buildings into 4 damage levels. In addition, we separated the age of buildings by comparing with the National Land Image Information published by Geospatial Information Authority of Japan (GSI), and divided into wooden and non-wooden buildings with each shapes of buildings. And that, we developed approximately 320,000 GIS data by checking up with the Fundamental Geospatial Data published by GSI. In addition, we verified the accuracy of aerial photographic interpretation data with visual judgment data by field investigations. Furthermore, we generated GIS data with 250 meter square meshes which interpolated seismic intensities and damage ratios, then compared these data with 2 different ages of wooden buildings both in case of the foreshock and the mainshock of the 2016 Kumamoto earthquake.

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 Recently, the problems concerning deterioration in the laminated rubber bearings has become obvious. In order to protect laminated rubber bearings from fracture during earthquakes, establishing adequate damage assessment technique is an urgent issue. In this research, the acoustic emission (AE) method which is one of the non-destructive testing methods was used for damage assessment of the laminated rubber bearings.
 This study observed AE activities by laboratory tests. The AE activities and their parameters of the damaged bearings were compared with those of new bearings. The results of the cyclic compression loading tests showed that the internal damage of the rubber bearings could be estimated through the activities of the AE parameters. Many AE hits and large AE energy were observed from the damaged rubber bearings through the cyclic compression loading tests, however, few AE activities were observed from new bearings. AE measurement technique was effective to assess the damage of the laminated rubber bearing.

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 Many bridges suffered huge damage due to 1995 Kobe earthquake in Japan. After this disaster, many concrete bridge piers were repaired and strengthened using steel plate jackets. If a steel plate jacket is peeled from concrete, the assessment its inside is so difficult. Thus, this study aimed to evaluate the peeling location between steel plate jacket and concrete.
 As fundamental study, the analyses were conducted to investigate the effect of peeling area to the detection wave-forms and the maximum amplitude were different in relationship between the regular and damaged specimens.

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 A magnitude 6.6 of JMA scale earthquake occurred in central Tottori prefecture in Japan on 21 October 2016. The fault plane was estimated to be a high-angle left lateral fault with the strike of NNW–SSE direction from CMT solution and after-shock distribution. Strong ground motions were generated near source area and caused severe damage to many houses. This earthquake was generated at the area where an active fault has not been confirmed like 2000 Western Tottori prefecture earthquake of M_j7.3. We constructed a source model by the forward modeling using empirical Green's function method. The source parameters of strong motion generation area were determined from the comparisons of the synthesized broad-band ground motions with the observed ones at several stations including near source. Resultantly, we proposed source model with 2 strong motion generation areas. The relationship between seismic moment and short period level of acceleration source spectrum of this earthquake is expressed in a scaling law of the past study.

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 Prediction of the number of evacuees in an earthquake disaster is an important issue for post-disaster management. In this study, as a fundamental investigation, the initial number and its decreasing process of the evacuees in five municipalities damaged by the 2016 Kumamoto earthquake have been compiled on a daily basis in conjunction with building damage, blackout, suspension of water supply, aftershocks and supply of temporary housing. In addition to the population occupying houses completely or partially destructed and the population without electricity and/or water supply, the time function representing the degree of social resilience has been introduced in order to model the temporal change of the number of evacuees (model 1). In addition, the post-peak decreasing process of the number of evacuees has been modeled using a mixed exponential distribution composed of three kinds of exponential functions corresponding to the short-, medium- and long-term effects (model 2). The change of the number of evacuees have been characterized by the model coefficients.

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 Many of the residential land were damaged by the 2016 Kumamoto earthquake. Large scale embankment slopes and retaining walls collapsed in the residential land of Kumamoto City, Mashiki Town, Nishihara Village, Minamiaso Village. Therefore, local government suffered from the 2016 Kumamoto earthquake asked Ministry of Land, Infrastructure and Transport for Post-earthquake safety assessment. Approximately 1, 000 Post-earthquake safety assessment carried out an investigation into approximately 20, 000 residential land by the end of May from April 17.
 In this paper, we analyzed the damage situation of retaining wall, ground and slope for each district and damaged items from the result of risk assessment survey by the 2016 Kumamoto earthquake, and perfo s rmed a comparison with the past other earthquake damages.

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 The 2011 East Japan earthquake induced widespread liquefaction not only in Tokyo bay area but also in inland area of Kanto region, which damaged numerous residential houses and public buildings. This paper uses three-dimensional dynamic effective stress analyses to evaluate the mechanisms and effects of large-space latticed walls and drains and their combination, which can be installed as measures to mitigate liquefaction of grounds of existed residential houses and buildings. Numerical results show that the shear stress in the walls parallel to the direction of ground shaking is significantly larger that that in the walls perpendicular to the direction of ground shaking.

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 This study is based on the previous three-stage and two-parameter ductile fracture model proposed by our research group, the equivalent plastic displacement at element failure during simulations is obtained by notched specimen tests, and an improved ductile fracture model is presented considering the effect of high stress triaxiality during both the plastic stage and the softening stage. The relationship between the plastic displacement at element failure and a nonuniform ratio (nonuniform ratio is the ratio of the average value of stress triaxiality of notch tip and center) is determined by a series of tests and analyses. Detailed finite element analyses that employ the improved ductile fracture model are show to predict ductile fracture behavior under high stress triaxiality with good accuracy across the mesh sizes, notch radii, and notch degree in terms of ductile crack initiation point, ultimate load point and load-displacement curve.

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 The seismically isolated tunnel, which is one of the countermeasures for linear underground structures against earthquakes, is characterized by reducing the transmission of ground strain to the tunnel by smoothing the tunnel strain in the section where the isolation structure is applied. Therefore, it requires a sufficient length of seismic isolation section. Thus, in this paper, as an attempt to shorten the length, the seismic isolation with both functions of Slip and Separation (SaS) is proposed. It is a new seismically isolated tunnel with flexible joints with a function of small amount of displacement absorption at both ends of slip-type seismic isolation. By analyzing earthquake tunnel axial response of the shield-driven tunnel in surface soil deposits with SaS isolation structure and comparing it with the case of conventional slip-type seismic isolated shield-driven tunnel. Then, this paper demonstrates that SaS seismic isolation structure shows a remarkable effect of reducing the tunnel axis distortion which is superior to the conventional seismic isolated structure.

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