Long-period ground motion class, as an evaluation method for the action difficulty during the shaking and the indoor damage in high-rise buildings, has been issued by Japan Meteorological Agency in 2013. Applicability of this method based on the absolute velocity response spectra (AVRS) should be validated by the actual floor response records and indoor damages in high-rise buildings. In this study, we propose the evaluation method of the AVRS by taking into account the participation function and variation of the fundamental natural period during the massive shaking. Using the floor response records of super high-rise residential buildings during the 2011 off the Pacific Coast of Tohoku earthquake, the proposed method provides better evaluation of AVRS than the current evaluation method. Relationship between the actual indoor damage and long-period ground motion class is clarified from the equation of the building response and the damage evaluation value based on the questionnaire survey.

The Fukui Earthquake wreaked havoc on the Kuzuryu River levee. In this study, we carried out microtremor observations densely on the Kuzuryu River bank. An extended SPAC analysis was applied to the collected array observation data to estimate Rayleigh wave phase velocities. Transfer functions between the top and toe of the dike and H/V spectra of the levee crowns were calculated to determine the predominant periods of the embankment-ground systems. S-wave velocity structures were back-analyzed based on the H/V spectra. It was confirmed that the earthquake damages on the embankment were harmonized with the back-analyzed structures.

This study investigated the cyclic softening and volumetric compression behavior of fine grained soil under various plasticity index. The volumetric strain was obtained using the drainage test after cyclic loading, and it was observed the effective stress path and stress-strain relationship during cyclic loading process. The volume strain after cyclic loading is different for Liquefied soil and cyclically softened soil. The soil became to liquefaction will cause a large volumetric strain. The main conclusion of this study is that there is a difference in cyclic softening and volumetric compression behavior due to the difference in plasticity index. The non-plastic silt was liquefied and the clay undergone cyclic softening. The volumetric strain after cyclic loading decreases as the plasticity index increases.

Nowadays, scenario-based strong motion prediction is strongly required quantitatively to show its variation or uncertainty. We focus on the variation or uncertainty of source parameters such as area and stress drop of strong motion generation area (SMGA). Repeating M6-class plate-boundary earthquakes occurring off Kesennuma, northeast Japan, were analyzed. The latest event on May 13, 2015 (M6.8) has 2 SMGAs, and each event in 1973, 1986 and 2002 has one SMGA. SMGA1 of the 2015 event and SMGAs of the 1973, 1986, and 2002 events are close to each other in space, and their spatial extent was almost same. The variation in the estimated stress drop of SMGA is approximately less than 1.6 times of the smallest event.

Effects of rotation of orientation on amplitude and duration characteristics have been evaluated by use of two orthogonal horizontal components of accelerograms of ground motions. Amplitude (PGA and total power) and three kinds of duration (significant duration, uniform duration and bracketed duration) are calculated for rotated waveform of acceleration by various angle ranging from 0 to 180 degree using accelerograms recorded during Off the Pacific Coast of Tohoku Earthquake, 2011. PGA and total power show partially and completely sinusoidal functional form, respectively, in terms of rotation angle. Significant duration is approximately sinusoidal with negative correlation with total power. Bracketed and uniform duration show rather irregular tendencies. Furthermore, histograms of the ration of the maximum and minimum values to the median for each index and corresponding rotation angle are calculated and the mutual relationships among the indices are examined.

A number of buildings were collapsed at the center of Mashiki city located about 2 km from the Surface Faults during the 2016 Kumamoto Earthquake. On the other hand, there are no collapsed houses in the Shimojin areas above the surface faulting located about 3km east from the center of Mashiki city. This paper discussed relation between strong ground motions and building damage in the center of Mashiki city and the Shimojin areas during the 2016 Kumamoto Earthquake. The estimated long-period ground motions (1∼2s) of fault parallel component in the Shimojin areas by the theoretical method are smaller than that in Mashiki city. The radiation amplitude patterns of S-waves from the seismogenic layer are small in the near-fault region (<1km), that is one of the reasons for the underestimate. The other hand the estimated long-period ground motions (about 1.5s) of fault normal component in the Shimojin areas by the theoretical method are larger than that in Mashiki city. These trends of the estimated long-period ground motions were harmonious with building damage.

When we conduct the prediction and judgement of liquefaction, the liquefaction properties of soils are evaluated by means of undrained cyclic shear test using in-situ soil specimens. It is considered that there are uncertainties in the liquefaction strength curve obtained because of inhomogeneous of in-situ ground, sampling disturbance and failure mode of elementary test. In this paper, the cause of deviatoric variation in the liquefaction resistance of soils is analyzed based on the data of in-situ specimen collected by Public Works Research Institute after the 2011 off the pacific coast of Tohoku earthquake. As the result, the authors clarified the tendency of the cause of variation included in the liquefaction resistance curves, and showed the superiority of evaluating the degree of liquefaction from the view point of energy.

Earthquake damage occurs due to residual ground deformation when soil liquefies. The residual deformation consists of lateral spreading and settlement. Few attempts have been made to determine the effect of lateral displacement on settlement following liquefaction. In this study, cyclic loading tests under undrained condition were conducted for clean sand using a hollow cylindrical torsion test and reconsolidation tests were carried out following various residual shear strain applications. It was shown that reconsolidated volumetric strain decreases as residual shear strain increases, with a maximum of 20% decrease in loose sand and 50% in dense sand.

Averaged stress drop equations are important in fault modeling for predicting strong ground motions, because they relate the outer and inner fault parameters in an asperity model. We examined several equations, including an equation of a circular crack by using the seismic moment, the area of the asperities, and the stress drop on the asperities. We compared the relationships between the seismic moment and the seismic fault area calculated by each equation with the existing empirical relationships, and concluded that the equation of a circular crack can be applied to small crustal and subduction plate-boundary earthquakes without surface breakings such as the May 1997 Kagoshima-ken-hokuseibu earthquake (M_W 6.1) and the 2003 Tokachi-oki earthquake (M_W 8.1). Most of the results showed that the equation of a circular crack can not be applied to large crustal or subduction plate-boundary earthquakes with surface breakings such as the 2016 Kumamoto earthquake (M_W 7.1) and the 2011 Tohoku earthquakes (M_W 9.0). This is because the equation of a circular crack was derived from the fault model without surface breakings. Our examinations showed that the stress drop equation by Fujii and Matsu'ura (2000) and the dynamic stress drop equation by Irie et al. (2011) for vertical strike-slip faults can be applied to the Kumamoto earthquake and that the dynamic stress drop equation by Dorjpalam et al. (2015) for thrust faults can be applied to the Tohoku earthquake.

We investigated the possibility of joint inversion of surface-wave phase and group velocities toward better estimation of subsurface S-wave velocity structure model. Our numerical experiments showed that the combined use of phase and group velocities that will be obtained from the same dataset has an advantage in constraining thickness and S-wave velocity of the shallower layers without deploying smaller arrays. We applied this technique to microtremor array data measured in the Kathmandu Valley, Nepal (sensor to sensor distances range from 137 to 801 m). Distinct wave trains corresponding to surface waves (Rayleigh and Love waves) were detected by seismic interferometry, making it possible to obtain dispersive characteristic of surface-wave group velocities in the higher frequency range. The estimated S-wave velocity structure model using the joint inversion without smaller array (r > 240 m) corresponds well to those of existing results, indicating that our approach can be a reasonable tool to reduce time and effort for actual microtremor survey.

It is important to validate reproducibility of observed records based on a dynamic rupture model that consider interaction on a fault plane physically. We analyzed the dynamic rupture model with rupture time constraint and the dynamic rupture model with spontaneous rupture for the 2016 Tottori-Chubu earthquake. We extracted information of change rates of stress to slip and stress drops from the slip model by the previous kinematic waveform inversion as much as possible, and we successfully reproduced fault rupture behaviors and near source strong ground motions.

We always attempted to grasp the hazard considering the ground vibration characteristics of the area by a relatively simple method using the H/V spectrum ratio of the microtremor single point observation. We compared the dominant period peak obtained from HVSR of microtremor always with the dominant period peak obtained from strong motion observation and confirmed a certain degree of correlation. Therefore, as a hazard evaluation of the ground, we examined the applicability of hazard multiplied by Tm and Rm of HVSR. It was confirmed that the hazard map created is consistent with the AVS 30.

Although a cyclic undrained triaxial test with constant cell pressure is the most popular laboratory test method for estimating liquefaction resistance of improved soil by chemical grouting and unsaturated soils, it is assumed that underestimation of liquefaction strength was reported due to necking of the specimen at extension side. In order to solve these problems, cyclic undrained triaxial tests under mean principle stress p constant condition for improved soil by chemical grouting and unsaturated soils were carried out in this study. And then, the results from these tests were compare with the result of usual liquefaction test by cyclic triaxial test apparatus.

Effects of subsurface soil properties on the spatial variability of ground motions between adjacent sites are examined by analysis of site response considering heterogeneous soil models. The statistical analyses of coherence of the ground motion indicate that the spatial variability increases as the size of the soil model is increased in the depth direction, but the spatial variability becomes stable even if the soil model is deepened from a certain depth. That depth of the soil model can be considered as the depth that affect the spatial variability of ground motions h_r, and it is found that h_r becomes deeper as the distance between observation sites gets larger.

The objective of this study is to identify the deformation characteristics and pore water state of unsaturated soils during dynamic loading. In this study, laboratory tests have been carried out to understand the liquefaction behavior of unsaturated soil with the varied pore water state. To change the moisture condition in the unsaturated soil air entraining agent was added into the unsaturated soil sample to forcibly change the state of the pore air and pore water and to imitate the condition of soil during mudflow slope failure due to the earthquake. As the test results, it is concluded that the dynamic deformation behavior of unsaturated soil is not determined only by the amount of water but also greatly depending on water state (pore air and pore water).

The effects of partial fairings and grating slabs on reducing tsunami-induced forces on bridges were studied. Fairings are effective to reduce drag, but have limited effect on reducing lift. Therefore, this study conducted numerical simulations to propose an effective fairing and an open grating floor slab. A semicircular fairing was attached to the side of the bridge deck model and a grating floor slab was modeled as a hollow space in the deck. Forces on the bridge deck model were compared between various types of models with and without a fairing and a grating slab. The results show that using a fairing and an open grating slab can reduce lift as well as drag caused by a tsunami. A fairing that covers more than 75% width with an open grating slab could reduce both the drag and the lift in 20% compared to the original bridge model.

The coefficient of lateral subgrade reaction of pile is generally given in proportion to -1/2 to -1 power of the pile width. However, since this relationship was obtained from the test results of relatively small diameter piles, the applicability to large diameter piles has not been clarified. The influences of pile width and pile stiffness on lateral subgrade reaction were investigated by centrifugal model tests. When the pile diameter is very large, the lateral subgrade reaction converges to a constant value. The validity was confirmed in comparison with the horizontal loading tests on actual ground.

Design ground motions used for verification of load carrying capacity of road bridges are set considering the influence of variations in the seismic vibration characteristics and the like, but the possibility of occurrence of earthquake motion exceeding the design ground motion cannot be denied. Moreover, it is considered that it is difficult to secure performance against extremely large actions that do not conduct direct design checks such as tsunami, slope deformation, fault displacement, etc. Therefore, we present the results of research on design method of the damage scenarios of bridges. The research aims to make it possible to build bridges that are highly resilient against excess action by considering the fatal state for whole bridge system, or that are easier for emergency restoration than usual.

On seismic design of underground reinforced concrete structure, numerical analysis is applied considering material non-linearity of structure and surrounding ground. On its past retrofit study, laterally cyclic loading test and its analyses were carried out, to confirm the effectiveness of cement-treated soil improvement adjacent to structure. Two types of effective stress analyses were conducted considering material non-linearity of liquefiable ground and cement-treated soil improvement with subloading surface model, one is two-dimensional block-type and another is three-dimensional lattice-type, to confirm its effectiveness. Based on the response results of structure and soil improvement body, rational and acceptable specifications of cement-treated soil improvement were presented.

In regards to seismic response of secondary systems, maximum floor acceleration and floor response spectrum have been studied by many researchers. But characteristics of seismic torsional responses of secondary systems have not been clarified yet. In this paper, seismic torsional responses of secondary systems are investigated through response history analysis. A structural frame for secondary systems is assumed to be linear without irregularity. Secondary systems are also assumed to be linear but with plan irregularity. Characteristics of seismic torsional responses of secondary systems are clarified comparing with those of primary systems.

In this paper, free vibration and shake table tests of uplifting structures with asymmetry due to mass eccentricity are conducted. The effect of asymmetry on response with uplifting is experimentally examined. Moreover, a formula based on the balance of energy in the undamped free vibration in an uplifting excursion is modified and applied to estimate the maximum force, and the correspondence with the test results is confirmed. It is shown that rocking angle and story shear coefficient are shifted to positive or negative side due to asymmetry in the structure, and that the prediction by undamped free vibration theory roughly corresponds to the trend of test results even in asymmetric uplifting structure.

In this article, the time-varying function of ground acceleration is formulated by using Fourier amplitude and the difference of Fourier phase angle. Then the time-varying function of the momentary energy input, proposed by Inoue and his co-authors, to a linear elastic SDOF system with viscos and complex damping is formulated in the form of Fourier series. The numerical analysis results show that (1) the time-varying function formulated using Fourier series corresponds to the envelope of ground acceleration, and (2) the maximum momentary input energy evaluated from formulation in this paper agrees well to that obtained from time-history analysis results.

We propose a method to identify story stiffness and damping coefficients through responses of shear type multistory building influenced by SSI effects. It is assumed that sway and rocking motion of the base and the horizontal motions of all the floors are observed. This method utilizes the base-fixed modal responses of substructure models extracted from the whole SSI model with using quasi-complex modal parameters. Having applied this method to the numerical model of a 6-story RC structure, the evaluated story stiffnesses and damping coefficients coincide well with the target values.

Analytical method to detect internal void of seismic rubber bearing was studied. Currently, there is no way to evaluate the presence or absence of internal void of a seismic rubber bearing without cutting it. Therefore, this study aimed to clarify how elastic waves are affected by a void in the seismic rubber bearing using numerical analyses. The validity of this numerical analysis using RCIP method was shown by comparing the experimental results with the analysis results. The results showed that the void affected the amplitude of the observation waves, if the void was near the receiver.

Upon the Great East Japan Earthquake, the city gas suppliers in the Tohoku region suffered from tremendous damage, and 16 suppliers took measures to suspend supply to ensure security. Among them, at the Sendai City Gas, which stopped supply of approximately 360,000 houses, the damage of the low-pressure gas pipeline was concentrated in the improved hill. In this paper, we analyzed the damage of the low pressure gas pipeline at the improved hill considering the depths of cut and fill estimated from aerial photogrammetry.

To investigate shaft friction of a piles during an earthquake, a horizontal cyclic loading test with overturning moment, a vertical monotonic loading test, and a vertical cyclic loading test were conducted by using a geotechnical centrifuge. The amplitudes of the shaft friction under the horizontal cyclic loading were remarkably larger than those under the vertical loadings. This tendency was significant at the upper part of pile, suggesting that the horizontal subgrade reaction on the pile increased the confine pressure around the pile.

Estimation of yield load for Cross laminate timber (CLT) bolt connection with steel plate were performed and confirmed by experiments. Estimation were based on the European yield theory. The parameter of estimations and evaluation were connection types (single, double shear with steel attached plate and double shear with inserted steel plate), thickness of CLT (3L3P l=90mm and 5L5P l=150mm) and diameter of bolts (d=12, 16, 20 mm). Calculated yield loads were in good agreement with experimental results in the range of normally used length diameter ration of connector (l/d).

Based on the earthquake response analysis, the Building Standards Law in Japan requires that a steel-braced frame must withstand an increase in stress of up to 1.5 times in the event of an earthquake. On the other hand, a similar provision was enacted for a wood-braced frame, but it is believed that there is room for rationalization with respect to the design force amplification factor “beta.” Therefore, the intention of this study is to propose appropriate design force amplification factors corresponding to the type of wood-braced frame by the earthquake response analysis using different types of wood-braced walls.

At the transition zone between embankment and bridge, lateral resistant force of ballasted track likely to decrease by the deformation of embankment under earthquake. Particularly, under the high temperature in summer season, axle load of rail increases and the risk against rail buckling tend to increase. To evaluate the stability against rail buckling by the deformation of embankment and ballast, shaking table test with coupled scale model of ballasted track and structure was carried out. Reinforcement of embankment and counter measure against rail buckling effectively prevented the rail bucking under the large earthquake.

A seismic response analysis method using high-fidelity model for large-scale reinforced concrete structures is being developed. In this research, implementation of a constitutive relation of concrete and an appropriate model contraction method for reinforced concrete structures are described. Especially, implementation of the constitutive relation of concrete which is suitable for conjugate gradient method is important. We show the performance of the developed method using analysis of loading tests of a reinforced concrete structure. We also show the convergence check of analysis of reinforced concrete structures as basic validation of the developed method. We finally apply above method to a seismic response analysis of a simple nuclear power plant building model and discuss applicability of the method.

Natural period and damping ratio are important vibration characteristics in seismic design. These characteristics can be evaluated using the public database of the 3-D Full-Scale Earthquake Testing Facility of the NIED, referred to as E-Defense. However, it has been pointed out that the rocking motion of a shaking table influences the vibration characteristics when superstructure weight is large. A larger than typical damping ratio has been observed for a few specimens in a previous study. This study focuses on the impact of the rocking motion of a shaking table with a large weight RC specimen as the target. Moreover, the vibration characteristics are corrected based on the rocking motion and evaluated using a system identification approach.

In this study, the collapsing simulation for timber house was conducted in order to estimate the seismic damage quantitatively. Wallstat, which is numerical analysis program for timber frame structures, is used for the collapsing simulation. The two-story timber house and 12 observed earthquake waves were used for the simulation. Correlation between the response acceleration and seismic damage, calculated by non-linear state of seismic walls such as elastic, plastic, decreasing strength and loss of strength, was found in the analytical results.

Authors plan to introduce a real time seismic diagnostic system to the disaster prevention centers. This system consists of the seismometers installed in the building and observation data are saved in Internet clouds. Immediately after the earthquake, the system performs a simple diagnosis on the residual seismic performance of the building and notifies the results by e-mail. In a few hours after the disaster, the system conducts a detail analysis and evaluate the damage section of the structure. This paper explains the proposed system and introduces the results of trial operation to the actual city hall buildings.

Train operation control during earthquakes is based on the intensity of ground motions observed by seismometers which are installed at a certain interval. To improve the stability of running trains, it is important to consider not only the ground motions but also the structural responses along railway lines. In this study, we observed seismic and microtremor motions at a target railway section to investigate vibration characteristics of both the subsurface ground and the structures performing. Examining the observed data, we propose the method to consider both characteristics and conclude the method is useful to make the train control more appropriate.

The variation of daytime population affects the performance of tsunami evacuation. This study comparatively studied two municipalities nearby Sendai city, whose mortality rates by the East Japan Great Earthquake Tsunami differed much from each other. In addition to the effect of increase and decrease of the daytime population, author discusses the road network which connects coastal area to high land, the preparedness for tsunami evacuation based on past tsunami experiences, the large seaport artificially excavated 40 years ago, the visibility of sea, and the difficulties to control the visitors who are in the commercial areas, in the swimming beach and on the roads.

The assessment model for post-earthquake serviceability of utility lifelines had been proposed and validated by authors. However, the model tends to slightly overestimate the time required for restoration with some earthquakes. Therefore, in this paper, we examined a method to improve the accuracy of the estimation model focusing on the fact that the difference in disaster scale affects the time required for restoration. We define two indicators: the first represents the ratio of observed to the estimated value using cumulative affected population. The second represents the disaster scale using weighted PEX (Population Exposure to shaking intensity). Based on the relationship between the two indicators, estimated values of time required for restoration in electric power and water systems are corrected to agree with observed values. It is shown that the accuracy of estimation for the major earthquakes tends to be improved the time required for restoration.

In this study, we discuss the effects of earthquake-induced compound disasters that have not been considered so far. That is, considering the victims trapped in the damaged house where the evacuation behavior cannot be performed due to indoor scattering and the collapse of houses, we proposed the human damage evaluation formula on compound disaster of earthquakes and tsunamis. In addition, damage evaluation was performed using this formula in Kushiro City, Hokkaido, and even if evacuation started simultaneously with the occurrence of an earthquake, a scenario was revealed in which approximately 20,000 residents would die from the tsunami due to trapped-in debris and other factors. Furthermore, we aimed to propose an example of a safer urban form as a fundamental disaster prevention for Kushiro City based on the social phenomenon of declining birthrate and aging. On the basis of the result on the future population prediction applying the cohort model, we estimated the mitigation effect on the self-help by residents, the mutual-help by neighbors, and the public assistance by the local government, and we considered the ideal way of the disaster mitigation strategy which should be in the future.

In recent years, high-rise buildings are required to possess the higher performance for earthquake disaster, not only for the conventional input ground motions of L1 and L2, but also for the L3 earthquake motions (maximum considered earthquake). Also, important facilities such as high-rise building is adopting the idea of the resilience based design in U.S.A., which comprehensively evaluates the higher seismic performance of buildings not only safety but also economical and recoverability. We set criteria targeting L1 to L3 earthquake for existing high-rise building, and made a comparison by earthquake response analysis between non-damping and damping reinforcement models. First, we probabilistically evaluated reduction of earthquake response value by damping reinforcement, and considered the cost effectiveness. As a result, expected damage cost greatly decreased, and there was merit in total price including cost of damping. Next, we made an evaluation using the life cycle cost considering earthquake occurrence probability, but results were different depending on earthquake probability evaluation model (engineering model by L1 to L3 earthquake, or the seismic hazard model from the earthquake ground motion prediction map). From now on, it is thought that probability evaluation model based on consensus with the societies of science and engineering will be important for promotion of higher seismic performance, such as the resilience-based design.