A “k-out-of-n shutoff system” has been defined in order to examine the property of emergency control criteria of city gas supply based on seismic monitoring. The functional fragility function describing the probability of shutoff in a service block in terms of observed spectral intensities within the block was developed for emergency shutoff of city gas in the 2011 off the Pacific coast of Tohoku Earthquake. System properties of k-out-of-4 systems (k=1, 2, 3, 4) were compared and clarified. The bootstrap simulation adopting replacing / non-replacing resampling was performed to generate 10, 000 samples of k-out-of-n shutoff systems. Average and standard deviation of shutoff ratio obtained from the entire samples provide useful information for management of shutoff activation.

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 In this study, statistical features of frequency dependent damping models of SH wave in the subsurface ground are investigated. The damping models are identified from the vertical array observation records installed in the various locational conditions sites.
 We discussed the appropriateness of damping models estimated from the seismic ground motion data recorded from the dense vertical array observation system located in the typical horizontally-layered ground. The frequency dependent model and the frequency independent model are compared with reference to information criterion. Akaike's information criteria show that the frequency dependent damping model is adequate to explain the observation records.
 Then, frequency dependent damping models of 29 sites identified from seismic observation data recorded by the vertical array observation system are analyzed statistically. It followed that average damping models grouped by the topographic classifications or the representative S wave velocities are obtained.

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 Determining the accurate shape of active fault is an important subject from the viewpoint of both hazard mitigation and urban planning. Traditionally, the methods for that purpose are roughly categorized into two types. One is based on the fault-related fold theory consisting of some fundamental deformation patterns such as the layer-parallel slip, the flexural slip, and the inclined shear, the other is based on the inversion with the Okada model using Green's function defined on a semi-infinite elastic body. Understandably, the fault-related fold theory is not applicable if the geological fold cannot be recognized at the ground surface. Also, the use of the Okada model is limited only to semi-infinite elastic body formed by a single material. In order to avoid these drawbacks, we have developed a novel inversion system by coupling the FEM with the topology optimization. We first define a set of mathematical programming for fault shape detection with a special regularization, and then perform parameter adjustment of the objective function to be minimized. Finally, the precision of proposed system is confirmed through some numerical examples. The results show that the system successfully detect the fault shape without any predefined information even if multiple faults exist.

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 The nomograph of seismic damage estimation has been proposed for a general railway bridge, whose damping is depending on its natural period. Therefore, it might not be applied to the structures with various damping characters. Then, the new nomograph estimating a seismic damage of structures with various damping was proposed. This method evaluates a response ductility simply by using PGA, PGV, the natural period of structure, yield seismic intensity, and damping. It was checked that the variation coefficient of the fragility curve given by the proposed method is smaller than that estimated only by using a single parameter of the earthquake motion. Consequently, the proposed nomograph estimates the damage of the structures having arbitrary damping and natural period, considering resonant motion due to an earthquake.

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 The damage positions of pile are affected by the soil-pile interaction and the different damage position affect the seismic response of structure. As the fundamental study on this problem, we study the effect of the damage position on pile by sensitivity analysis. In the analysis, we use the analytical model of the soil and pile that complies with shaking test. Using this analytical model, we change the damage position, and study the difference of seismic response. From this analysis, we found that if the damage position is deeper than 1/β(β: the characteristic value of a pile), the response of the structure is restrained to a limited extent, whereas the shallower damage position than 1/β dominates the response of the structure significantly. Especially, due to the damage at shallower position, the displacement response can be increased.

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 This paper points out the refinements about the seismic damage estimation formulas and various correction factors for buried water pipes through a comparative analysis between the damage to water pipelines in Sendai City and Iwaki City caused by the 2011 off the Pacific coast of Tohoku Earthquake and the damage estimated by four kinds of existing damage estimation formulas.
 In addition, this paper shows that an existing damage estimation formula using modified correction factors, such as pipe material, pipe diameter and soil condition, enables us to improve the damage estimation accuracy.

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 This study conducted two-dimensional and also three-dimensional analyses on tsunami forces acting on a girder bridge using OpenFOAM, which is open-source software. The trapped air between the girders affects on the pressure distribution acting on the bridge due to tsunami flow. As the trapped air escaped from girder ends, obtained tsunami loads from the two dimensional analysis was different from the experimental results. The difference was particularly in lift and moment. A three dimensional analysis was necessary to estimate the tsunami loads for girder bridges, which showed good agreement with experimental results.

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 West Asian region is a very active area of a crustal deformation, many historically huge earthquakes have occurred, crustal movement has continued up to today. To investigate the most suitable solution for the crustal movement will contribute greatly to this region's earthquake and tsunami disaster mitigation. Pitazzoli (1986) suggests that traces of upheaval caused by the AD 365 earthquake on the Greek coast in the Holocene shows the event which occured in the period called the Early Byzantine tectonic paroxysm (EBTP) turbulent period from the mid-4th to the mid-6th centuries. Evidence of a 9 m upheaval by the AD 365 earthquake movement was found in a detailed survey and by radiocarbon dates by Pirazzoli et al. (1996), the date of the casualties' were estimated from coins found in a collapsed house by Stiros (2010), and by the ruins of an old harbor that existed, give the proof of the position of the sea surface at that time by the location of the quay wall. The AD365 earthquake occurred near Crete (e.g., Fischer (2007), Shaw et al. (2008), Stiros (2010), Papadimitriou and Karakostas (2008)). This study selected the most reliable parameters, which each researcher defined, and non-uniform distribution in the fault plane, which is based on Papadimitriou et al. (2008). The calculation of the AD365 earthquake's waveform gave an indication of th maximum acceleration by using the stochastic Green's function method with the selected parameters. Thus, an estimation of the damage to masonry structures could be made. The ancient Crete city of Aptra amd Chania were both hit by the AD365 earthquake. Aptera built on out-cropping rock will be 80 % destroyed whereas Chania built on thick sedimentary layers will be completely destroyed. Chania in the north-west of Crete is expected to be high seismic intensity area. Thus, it is necessary to pay attention to the seismic risk at the high densely populated area with thick sedimentary layers.

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 A lot of railway embankments suffered to the collapse, crack among wide area in East Japan, by the 2011 off the Pacific Coast of Tohoku Earthquake. All railway embankment maintained by East Japan 8 Railway Company within much damaged area are investigated for categorizing with height, gradiation, geomorphologic classification, and so on. The result of this investigation is databased. And the influence level of each category is analyzed by assuming weight points and verification with the database.
 This study says that the difference between damaged and no-damaged embankment has a strong correlation to geomorphologic classification, emvironment around the site, height of embankment, past-damaged, and so on.

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 The 2011 Off the Pacific Coast of Tohoku Earthquake caused damages of railway embankments in East Japan area widely. We calculated the deformation of damaged and no-damaged railway embankments in 10 areas. We used the Newmark method (circular slip surface analysis) for calculating the deformation.
 This study says that railway embankments of which yield seismic intencity is less than 0.3 was severely damaged. Neverthless, those of which yield seisimic intencity is over than 0.3 was severely damaged in case that the groundwater leve was high, and the fine fraction content of lower embankment materials or upper ground soils were less than 35%, or bearing stratum contained thick organic soil layer.

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 Evaluation of residual displacement was conducted in order to simulate process of damage and non-damage to a residential fill slope, Nankodai 6 chome, Izumi Ward, Sendai City, Miyagi Prefecture, during the 2005 off Miyagi Prefecture Earthquake and the 2011 off the Pacific coast of Tohoku Earthquake. First, analyses based on Newmark's Sliding Block Method were carried out using ground motions of the 2005 main shock and 2011 main shock at the site estimated from temporary earthquake observation records. Analyses based on dyamic FEM calculation were then conducted considering the estimated ground motions. The result of the analyses due to the 2005 main shock and the 2011 main shock coincides with the actual damage and non-damage to the residential fill slope of interest.

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 Verification of strong motion at damage or non-damage site of interest due to a large-scale earthquake is frequently carried out based on comparison of observed and estimated waveforms. However, the strong motion estimation is sensitive because of different site factors between the site of interest and its circumference observation stations. Therefore, we proposed practical use of 3-D DEM calculation of tombstone nearby the sites of interest, in order to confirm the applicability of the estimation method for the strong motion. In this study, overturning analyses of tombstones in the graveyards in hypocentral region for the 2000 Western Tottori Earthquake were performed based on the estimated three component ground motions considering site effects. The calculated fall-down rates agree well with the actual data observed after the main shock.

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 During a scenario earthquake with M_W9.0 along the Nankai Trough, not only strong motion but also huge tsunami is predicted in Kushimoto Town, Wakayama Prefecture, Japan. In this study, first, based on the empirical relationship between microtremor H/V spectrum and site amplification factor, the site amplification factors from seismic bedrock to ground surface at the 525 sites in the tsunami attack area were evaluated. Seismic waveforms in the area were then predicted with very high density based on the SMGA models considering the empirical site amplification factors. Using the detailed distribution of several indices due to the predicted seismic waveforms, finally, we discussed the influence which the action of the strong motion has on tsunami evacuation.

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 Progress of numerical simulation technique such as DEM (Discrete Element Method) permits prediction of down-slope movement of rock debris to some extent. It is, however, not reasonable to predict how far the falling rocks reach and how seriously they affect structures in concern deterministically because large uncertainties are involved in the prediction. This study proposes a method to assess the probability of collision to the structures when a distribution of falling rocks are obtained by some numerical simulation methods. Severity of collision in addition to the probability is needed in order to assess the influence on the structures. Hazard curve with respect to residual distance, which is defined as the moving distance from the structure when the falling rock does not collide with it, is proposed and estimated.

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 The excess pore water pressure dissipation method is one of the liquefaction mitigation techniques. It is designed generally not to liquefy for the ground motion level 1. Though some kind of drainage effects might be expected even if a ground motion is larger than the level 1, the quantitative effects of this method is unknown. In order to quantitatively evaluate these effects, an effective stress analysis using the strain space multiple mechanism model is conducted for the centrifuge model tests which conducted in the past. In addition, in order to evaluate a drainage effect against the real large earthquakes observed in the past, an effective stress analysis using the same model is conducted for the ground model using in the centrifuge model tests.
 Based on the results of this study, it was found that the strain space multiple mechanism model might be applicable to quantitatively evaluate the drainage effects by the excess pore water pressure dissipation method in horizontal bedded ground during a large earthquake.

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 Based on the damage data of 819 bridges except the damage caused by tsunami among 960 bridges due to the 2011 off the Pacific coast of Tohoku Earthquake, the analysis in this report was carried out to make clear the relationship between the damage features and the structural characteristics, and the intensity of earthquake ground motion. The records obtained at 517 points observed in 6 prefectures in Tohoku region with the surrounding 4 prefectures of Niigata Prefecture, Gumma Prefecture, Tochigi Prefecture and Ibaraki Prefecture were used to estimate the intensity of earthquake ground motion such as the peak ground acceleration (PGA) and the peak ground velocity PGV by Spline interpolation method.
 As a number according to the damaged element of bridge, most damaged element is level differences behind abutments. Subsequently, there is much collapse of shoe. Moreover, damage about failure of a bridge pier or abutments is few. The damage behind abutments has few differences according to bridge type. Failure of shoe has occurred in a steel bridge mostly.It is found that the damage probability of level difference behind abutments becomes more than 30% around 30 cm/s of PGV, and that the damage of shoe has the high correlation with the component of velocity of an earthquake ground motion, but that it also has relationship with acceleration.

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 Damage points, damage lengths and damage modes of seawalls with or without steel-type piles at Yamada fishing port in Iwate Prefecture, affected by the 2011 off the Pacific coast of Tohoku earthquake tsunami were clarified by analyzing associated Google Earth data and structure drawings of subject 187 seawall units. Dependency of the damage ratios defined as the number of damaged seawall units divided by total number of exposed seawall units by the associated inundation depths and overflow depths was revealed, with considering the failure and non-failure mechanism on sliding and turning failure modes of the 42 seawall units without steel-type piles based on computation of safety factors.

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 This study aimed to examine the failure mechanisms of the Fujinuma Dam and introduce possible seismic strengthening methods for earth dams. The study consists of field and laboratory experiments and a numerical simulation of the dam. Laboratory experiments were conducted to acquire necessary information. For the seismic analysis, a coupled solid-fluid finite element formulation was applied. The observed and simulated motions of the 2011 Tohoku Earthquake were used as input motions. Frequency and dynamic analyses were performed thereafter; dam behavior and possible failure mechanisms are presented. In addition, the seismic strengthening techniques of the studied dam are introduced and discussed.

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 Three hundreds of fault rupture scenarios considering uncertainties are generated for both strike slip and reverse faults with magnitude around Mw 6.6, in this paper. Ground motions are simulated by stochastic Green's function method at 10,201 sites in 200 km x 200km area with 2km grids. Very simple distribution of average ground motion is derived from the results, however, distribution of variation coefficent is rather complex but accountable from radiation pattern and forward directivity effect.
 Applying fault rupture model on PSHA, it is expected to get over an intrinsic problems of general PSHA based on empirical attenuation formulae. The formulae are based on data set of observed ground motions at various sites due to limited number of earthquakes; i.e. spatial variation, although required design basis ground motions should be defined at a target site from an assuming source fault with uncertainties of repeating fault ruptures; i.e. temporal variartion. In probabilistic earthquake hazard analysis, this problem is supplemented by ergodic property. Using the calculated data sets above, ergodic property of uncertainties are examinned. Through the study, it is assumed that temporal variations are remarkably smaller than spatial variations. The results encourage future study for reducing variations of strong ground motions used in probabilistic analysis.

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 Experienced shear strain dependency of high damping rubber bearing which is induced by Mullins effect of rubber is one of influencial dependency to seismic responce. So the effect of experienced shear strain dependency on seismic responce of isolation structure should be evaluated.From past studies, we indicated that loading history must be taken into account. And then seismic responce analysis are performed by bi-linear double target model which is able to take into account the experienced shear strain dependency. From seismic responce analysis, the effects of experienced sherar strain dependency on seismic responce are evaluated.

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 If an earthquake occurs inland, a gap of a fault may appear at ground surface and it may reach several meters. Therefore, water pipelines across a fault must be designed carefully. However, the design method of ductile iron pipes with earthquake resistant joint buried across a fault is not established. In this study, we analyzed the behavior of ductile iron pipes with earthquake resistant joints buried across a fault and studied the behavior of joints every dip of a fault. In addition, based on the analysis, we clarified the availability of an estimate method of behavior of ductile iron pipeline with earthquake resistant joints buried across a fault.

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 It is very severe circumstance for underground public works structures such as subway tunnels that the surrounding soil is greatly distorted during an earthquake. This paper adds new knowledge to the previous paper which studied that what kind of base input-earthquake-motion waveform cause large shear strains in the subsurface ground.
 In this paper, a single-cycle-rectangular-shape wave is taken up as base input acceleration motion which forms a single-triangular-shape wave in the velocity of the base movement, and the shear strain induced in the subsurface is analytically studied. Then the mechanism of the subsurface strain generation by this excitation condition is elucidated, and it is pointed out that the amplitude and the rise time of the base motion velocity govern the magnitude of the shear strains. It is strongly presumed that the microscopic mechanism of shear strain generation that has been studied about the elementary wave is revealed in response of the subsurface to a real base excitation with a random waveform.

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 Wastewater treatment plants are usually constructed at coastal zone and river mouth area because of gravity system for collecting sewage. Consequently, they can be attacked by not only strong motion but also tsunami at earthquake time. In this study, we proposed isolation structural method against strong earthquake motion and tsunami by utilizing asphaltic viscous fluid isolator. Applicability of the method was examined by numerical analyses based on incompressible smoothed particle hydrodynamics. As a result, it is considered that wave pressure induced by tsunami can be reduced due to three-dimensional cushion effect of isolator.

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 In order to study the mechanism of wave force on bridge girder and propose the evaluation formula of tsunami wave force, by applying the bridge girder model, the experiment simulating bore wave at surge front of tsunami was conducted. The experimental results of wave vertical force, the pressures on the girder top and bottom surfaces were concentrated. As a consequence, it was found that the measured vertical force agreed with the integration of the vertical forces calculated by multiplying the pressures on the model bottom and compression areas of the model bottom, and from the results of wave height parametric study, it was obvious that the wave vertical force became greater with the increase of wave height. Therefore, it was concluded that the wave vertical force was the function of wave height and compression area of bridge girder bottom.

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 The purpose of this study is to select proper locations of disaster response bases in case of tsunami. The emergency traffic roads were graphed by means of the space syntax theory. The emergency traffic road network in Iwate Prefecture were analyzed following the fact of the 2011 off the Pacific Coast of Tohoku Earthquake. Further, the emergency traffic roads in Kouchi Prefecture and Shikoku District, where will be affected by tsunami associated with a gigantic earthquake in Nankai Trough, were evaluated following the same manner. Based on the results, proper locations of disaster response bases in Kouchi Prefecture were proposed.

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 Sliding bearing provide less seismic force delivered to substructures and are effective for ensuring the seismic safety of bridge structures. For more rational and effective use of the sliding bearing, the authors consider a damage controlling method by use of combination of sliding bearings, knock off members and displacement restrainers as bridge bearing. In this paper, a modeling method using spring elements of the proposed bearing for dynamic response analysis is verified through comparisons between experimental and analytical results.

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 The long-term use of wood is a means of mitigating global warming and rejuvenating forestry. Accordingly, the authors have been developing a liquefaction countermeasure that uses logs. To investigate the effect of this method against liquefaction, a large-scale shaking table test was previously conducted. Results of that experiment indicated that the log piling liquefaction countermeasure is more effective than soil densification, likely because of densification between piled logs and increase of horizontal earth pressure. In regard to this experiment, the present paper discusses the stress-strain relation and effective stress path, and considers the results of sounding tests at the ground between piled logs, comparing them with the shaking table tests and the results of element tests. The results confirm that the log piling liquefaction countermeasure is two times more effective than soil densification in the rage of relative density more than 60 %.

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 A deformation evaluation method for asphalt pavements on the ground improved by the grid-type improvement during and after earthquakes was examined. A liquefaction analysis was conducted to evaluated the effect of liquefaction countermeasure during the earthquake and a consolidation analysis was conducterd to evaluated ground deformation caused by dissipation of excess porewater pressure after the earthquake. And the analysis results of the grid-type improved ground was compared with non-improved ground and the chemical grouting improved ground. As a results, deformation reducing effect of the grid-type improvement equivalent to the chemical grouting improvement was obtained. It was shown that the combination of the liquefaction analysis and consolidation analysis is useful to evaluate deformation of the ground improved by the grid-type improvement. Forthermore, it was recongnized that the grid-type improvement with wide grid spacing has effect reducing subsidence.

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 We investigated an isolated bridge subjected to long-period ground motions during the 2011 off the Pacific Coast of Tohoku earthquake. We identified modal parameters of the bridge by using multi-degree-of-freedom systems model consisting of superstructures, piers, and pile foundations. The natural frequency and damping coefficients of the bridge were identified by analyzing the transfer functions computed by the observed acceleration data of decks, pier top, ground surface and pile foundation, compared with the theoretical transfer function.

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 Local government and other private companies have installed motion networks consisting of a large number of seismometers since the 1995 Kobe earthquake, for the purpose of obtaining information on seismic motion in real time and predicting damage immediately after the earthquake. By the way, some of the damage estimation system adapts instrumental seismic intensity calculated from the observed motion. The observation station at which the motion predominant in short-period is frequently observed causes high seismic intensity in the calculation and overestimation of damage. This study focuses on the observation stations in Hyogo Prefecture and attempts selecting the observation station which frequently records high acceleration in the short-period using earthquake records of recent small or moderate earthquakes and comparing differences between the observed value and the value estimated from attenuation relation.

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 A mechanism of the tsunami effect on Miyako Bridge which was survived from the 2011 Tohoku tsunami was discussed based on the video picture and the numerical analysis. The video picture clearly showed the tsunami was approaching to the Miyako Bridge with a slight angle of the tsunami wave front and the bridge was inundated with the tsunami. The analytical results showed that the maximum horizontal and vertical tsunami-induced forces were generated by the hydrodynamic pressure at the overhang, the girders when the tsunami wave acted to the superstructure. It was also suggested from the practical estimation that those forces could not wash-away the superstructure of the Miyako Bridge, which coincided with the actual performance of the bridge after the 2011 Tohoku tsunami.

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 Simulation of the in-situ behavior of pile foundation is necessary in the seismic design and assessment for target structural integrity and performance during earthquakes. Generally, the pile behavior is governed by its deformation. For commonly used flexible piles, this deformation is observed to be significantly greater near the ground surface and becomes negligible with increasing depth. This region of significant deformation is defined as the active pile length, L_a. To simply investigate the behavior response of pile embedded in a homogeneous sandy soil, a plane strain condition using the 2D finite element method in nonlinear analysis was done. The subloading t_ij model is used to model the elasto-plastic behavior of the soil and the pile is modeled as a 2D continuum-based beam element. Based on the rigorous solution, piles reach the ultimate state of its side soil under large lateral deformations. In this case, a soil wedge can be observed being pushed up along this active pile length. Therefore, a simplified method using the active pile length as a key parameter to describe the ultimate lateral resistance of piles embedded in sand is presented for more practical approach in the seismic design and assessment of piles.

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 Fracture of fillet welds and partial penetration welds was observed in past strong earthquakes, where the location of crack initiation is subjected to combined shear and tensile stresses. However, studies on ductile fracture under the coupling stress state are limited in the field of steel structures. This study aims to experimentally and numericaly investigate the effect of coupling stress on ductile crack initiation and propagation of several typical steels in bridge engineering. Two series of specimens made of three different steels are employed, where specimens are respectively under pure shear, shear and tension at the initial loading stage. The cracking processes of the specimens are studied. Meanwhile, absorbed plastic energy of the specimens is also investigated.

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 This study is a part of work aimed at clarifying the effect of unwelded ratio as well as welding depth and leg length on the initiation and growth of ductile crack in the steel beam-column connections. Cyclic loading experiments are conducted using specimens with unwelded portion inherent in the beam-column connection. Root gap existed in the cross joint of the beam-column connection in previous studies. But in this study, behavior of ductile crack initiation and propagation of such members without root gap is revealed. It is found that the unwelded ratio has a significant effect on the seismic performance of the steel piers. Even when the root gap is not existed, it is also confirmed that there is the same tendency as in the case of existing the root gap.

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 This study is aimed to investigate cracking mechanisms of welded steel joints. Effect of notch position on crack initiation, propagation and rupture of welded notched single bevel groove welded steel joints was studied by experiments and FEM analyses employing a newly proposed ductile fracture model. Singlebevel groove welded joints with notches at different locations, i.e., base metal, fusion zone, and heataffected zone, were considered. It is concluded that the ductile fracture model can well predict the fracture behavior of welded steel joints subjected to monotonic loading.

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 Damages of houses, sewer buried pipes, and roads subjected to severe liquefaction, which are distributed in mined areas at Fukashiba and Hiraizumi in Kamisu city, were clarified by analyzing the associated statistics. Road damages are related with differences in ground level which occur in the boundary between mined area and non-mined area. These differences might cause the partially damages of houses and the damages of sewer buried pipes such as vertical deformation or gaps at joints of pipes. It was also found that the deeper liquefaction layer causes the severer damage of houses.

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 A catastrophic debris avalanche that ensued from the 1923 Great Kanto Earthquake occurred near the rim of the Hakone crater, Kanagawa Prefecture; destroying Nebukawa town with loss of many lives. Its debris mass travelled along the Shiraito River; uprooting trees on both river walls, burying many houses, and pushed Nebukawa Railway Bridge to the sea. A simplified iterative approach is applied to this debris event for estimation of the velocity of debris slurry. Documented super-elevations of the flowing material along the bends of the flow path are used in this paper. An old topographical map is compared with the current terrain and real field data used as input parameter for the iterative procedure. Several stretches of the river channel are analyzed with the proposed approach and velocities of the debris flow are estimated for the chosen stretches.

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 Hidden-landslides that appeared in an earthquake are not always visible in aerial photographs. All the more because these hidden landslides are at risk of reactivation in heavy rains and snow melting times that follow the earthquake, it is often an urgent need for us to detect their presence for rational rehabilitations Recent development of remote sensing technologies allows us to observe changes in terrains in a very precise manner. However, to deal with land concervation issues, we need to extract Lagrandian soil displacements first, and then separate the hidden landslides. For the separate extraction of hidden landslides, moving average method is used herein to create a series of averages of different subsets of the full data set of the detected Lagrangian displacements, and the most appropriate square-window size for the hidden landslides is examined at Kizawa area where a 300m-long road tunnel was deformed by a hidden landslide.

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 Nozu et al. have been developing the SPGA model, which is suitable for the simulation of strong ground motions for subduction earthquakes. When the model is applied to a historical earthquake, it is desirable to construct an SPGA model which is consistent with seismic intensity data. In this study, as an example of the application of the SPGA model to a historical earthquake, an SPGA model was developed for the Gneroku (1703) Kanto earthquake taking into account seismic intensity data. The position of SPGA and the parameters were determined using the correlation diagram of seismic prediction and seismic intensity distribution. Proposed source model was found to well explain the seismic intensity data.

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 This paper describes the modeling of the end bearing capacity of pile for the two-dimensional effective stress analysis. First, we conducted the vertical loading test in the centrifugal field. Then we simulated the vertical loading test by the three-dimensional analysis to confirm the validity of the three-dimensional analysis. We proposed a model using non-linear spring elements for two-dimensional analysis. As characteristics of the non-linear spring elements, we used the hyperbolic relationship (Hirayama(1990)) that was determined by three-dimensional analysis. We carried out case studies. Thus, we could confirm the validity of the proposed model.

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 After the South Hyogo prefecture earthquake in 1995, adoption of seismic damper for highway bridges to absorb the kinetic energy of upper structure was increased. An ultra fine gained Zn-Al alloy was developed by means of thermommechanical control process. This alloy has super-plasticity properties at room temperature. So, it is effective in the construction of a seismic damper for highway bridges. In this research, cyclic loading test of laminated rubber bearing with Zn-Al alloy plug. Basic mechanical property is compared with lead rubber bearing. Applicability as seismic damper for highway bridges is investigated.

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 The 2011 earthquake of the Pacific coast of Tohoku occurred on March 11^th. Several natural rubber bear-ings of the viaduct in Tohoku district were fractured due to this earthquake. This type of damage was the first experienced in Japan. In this research, a three span continuous plate girder bridge with reinforced concrete piers was selected as a structure for examination. Natural rubber bearings were set up on the top of each pier. A fracture model of the natural rubber bearing was proposed in this research. Dynamic response analysis of the highway bridge considering the hardening and the fracture of the natural rubber bearing was conducted using T-DAP III. The observed record of the nearest point to the damaged highway bridge in Sendai was se-lected as seismic input motion. From the results of the dynamic analysis of the highway bridge, an increase of relative displacement in the natural rubber bearing, depending on the fractured bearing was confirmed in longitudinal direction. The possibility of a fracture progress of the natural rubber bearings was verified. And transversal direction, the rotational motion of the girder occurred after the fracture of natural rubber bear-ings. From these results, the response of the highway bridge considering hardening and fracture of natural rubber bearing was made clear.

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 Nankai Trough quake is predicted to occur in the near future and the disaster prevention and mitigation is becoming important. It is expected that the inter plate earthquake such as the Great East Japan Earthquake in 2011 induces severe damage caused by not only vibration, but also tsunami force from the disaster experience.
 Hanshin expressway has been conducted various disaster prevention and mitigation studies. As one of mitigation studies, the collision analysis between the large drifting ship and the Hanshin Expressway cable stayed bridge located along the coast of Osaka bay was conducted. In this study, the collision effect on the cable stayed bridge was obtained by using the 3-D frame analysis that is a conventional method for seismic analysis and taking the collision force evaluated from the fundamental physical low into consideration. From the results of this study, it was found that the effect of impact force on the cable stayed bridge is not critical.

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 It is important to consider the spatial variability of soil properties to evaluate the uncertainty of dynamic response of subsurface structures subjected to earthquakes. Although there are many proposed models for generation of stochastic fields, few researches have been conducted to understand the basic feature of the response variability of the system having those stochastic fields. This paper examines the response variability of the underground structures and surrounding ground subjected to the earthquake ground motion, modeled with random fields. Series of Monte-Carlo simulations were conducted for linear and nonlinear models under various conditions, e.g. shear wave velocity V_s, thickness H, correlation length of the ground shear stiffness θ, and so on. From those results, it turned out that the response variability can be estimated with the variance function proposed by Vanmarcke for liner model with choosing appropriate local averaging lengh, while for nonlinear model, the variance of the response becomes much larger than estimated by variance function when the ratio of local averaging length and correlation length takes a certain value corresponding to each response to be examined.

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 Risk evaluation of slope failure against nuclear power plants, which is induced by unexpectedly large earthquakes, has been urgent need for disaster prevention measures. Specially, for risk evaluation of slope failure, understanding of information such as traveling distances, collision velocities, and collision energies is very important. Discrete Element Method (DEM) such as particle simulation method contributes important role on predicting the detailed behavior of slope failure physics. In this study, instead of accurately predicting the complicated behavior of sliding and falling for each rock, we introduce the DEM modeling to evaluate the average traveling distance of collapsed rocks and its statistical variability. First, we conduct the validation test of the proposed DEM model on the basis of reconstruction of experiment results. Next, we conducted the parametric studies to examine sensitivities of important parameters. Finally, validity of the proposed method is evaluated and its applicability and technical assignments are also discussed.

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 We focus on sloshing behavior of intermediate state of solid and fluid, which simply model a liquefied layer. In order to simulate the behavior, we introduce common governing equaions representing both solid and fluid materials, and develop a numerical scheme in Lagrange coordinate system. It is verified by two types of numerical simulaitons: static behavior on a tilted recutangular tank and sloshing behavior. From the simulation results, free surface shapes are different between solid and fluid.

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 This report proposes a simple detecting method for non-linear characteristics of surface layer of the ground. Calculating time variation of dominant period and acceleration amplitude from ground motion record, relative displacement is calculated. The change of acceleration and displacement can be expressed in the characteristic diagram, then non-linear characteristics is known from the shape of the diagram. In the case of subsoil liquefaction, the shape is widely spread and some values which indicate non linear characteristics can be known.

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 Seismic retrofit design of a PC hinged rigid-frame bridge against Level 2 earthquake ground motions was performed by using seismic response control devices at piers and the central hinge, and continuing main girders at the central hinge section. Three-dimensional non-linear dynamic time history analyses were carried out using earthquake ground motions specified in the current specifications for highway bridges, in order to improve seismic performance of the bridge. Dynamic performances were compared by changing the type and arrangement of the seismic response control devices. For installing seismic response control devices at piers or the central hinge, effects on seismic response reduction were confirmed, compared with the as-built bridge. For installing shear panel dampers both at piers and the central hinge, more effects on seismic response reduction were confirmed. It was also found that continuing main girders at the central hinge section and installing shear panel dampers at piers was effective with retrofit areas and retrofit members getting smaller.

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 Many rubber bearings have been adopted to highway bridges with the application of the horizontal seismic force distribution design and the seismic isolation design. However, it is recently reported that a considerable number of LRB (lead rubber bearings) served for decades are suffered of evident deterioration damage. In this study, the mechanism of aging deterioration of LRB is disucced based on 3D FEM analysis of LRB under cyclic deformation due to the thermal action to the girder. Since the significant loss of damping performance can be attributed to the fracture of lead plugs observed in the experimental study, a particular interest is placed on the lead plug behavior under cyclic deformation at an extremely low rate and its contribution to the deterioration mechanism. The analysis result shows that plastic strain that can develop cracking and fracture is found to be induced in the tensile zone of the lead plug during cyclic deformation due to the thermal action.

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 To simulate the local buckling of steel pipe piles on damaged open-type wharves, we revised model parameters in the two-dimensional effective stress analysis as follows : 1) The appropriate modeling of shear strength of soil around the piles; 2) Using the real yield strength of steel pipe piles, not a standard value. However, using the bi-linear beam element for piles with coarse element division, it was difficult to grasp the detailed local buckling position and residual strength. In this paper, the M-φ relationships of steel pipe piles in consideration of the local buckling are obtained by three-dimensional FEM analysis using shell elements. It has been found that the accuracy of the numerical simulation is improved by the proposed M-φ relationships.

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