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Abstarct A new simplified method is developed for the analysis of the impedance and foundation input motion of foundations with a large number of piles. In this proposed method, the neighboring piles are replaced by a single equivalent pile. This process of replacement reduces the number of degrees of freedom, computer memory requirement, and calculation time. To validate the simplified method, the impedance and foundation input motion of a raft foundation and an embedded foundation supported by piles groups are calculated through both the simplified method and the rigorous numerical method. Results show that the proposed simplified method for the impedance and foundation input motion of a foundation with a large number of piles has sufficient accuracy and good computational efficiency.

A simplified method is developed to analyze the impedance and foundation input motion of foundations supported by pile groups. In the proposed method, neighboring piles are replaced by a single equivalent pile. This replacement process reduces the number of degrees of freedom as well as the required computer memory and calculation time. To validate the simplified method, the impedance and foundation input motion of a raft foundation and an embedded foundation supported by pile groups with rigid and pin-jointed conditions between the pile head and foundation are calculated using both a simplified method and a rigorous numerical method. The results show that the proposed simplified method for the impedance and foundation input motion analysis of a foundation with a large number of piles yields sufficient accuracy. The simplified method is also applied to estimate the dynamic response of an isolated structure with a foundation supported by 2203 cement–soil piles with consideration of the soil–structure interaction. The results show that the dynamic response of the structure can be precisely simulated using the simplified method.

Listening to a sound representing ground motion is valuable to intuitively understand an earthquake, compared with conventional methods such as observing waveforms, Fourier spectra, and response spectra. In this study, we propose a new method for generating sound representing an earthquake, which has several differences in comparison with existing methods. In our new method, an earthquake‐like sound is generated by modifying the frequency information of a generating function based on the symmetric Fourier analysis theory. Applying the method to existing seismograms illustrates three features of the sound generated by this method: the sound has the same duration as the seismogram, the sound pitch corresponds to the instantaneous frequency of the seismogram, and the sound volume corresponds to the envelope amplitude of the seismogram. Furthermore, we constructed a web‐based earthquake‐like sound generating system called Naion. Other applications will be implemented in the future.

Earthquake simulation is helpful in order for society to experience real seismic waves in safe environment. Cable-driven parallel mechanisms have advantages over conventional serial and parallel mechanisms. Prototype simulator which covers 1 m stroke in each direction has been built. In this paper, conceptual design of an earthquake simulator using cable driven parallel mechanism is presented. Spatial arrangement of cables is investigated in terms of the stability and safety of the simulator by dynamic analysis of the simulator. It was revealed that increasing the vertical angle of the cables with the ground while connecting them closer to the center of mass of the output link with low coefficient of friction between the ground ensures the most stable motion.

We measure an axial strain of CFT columns of real buildings by optical fiber sensor, and compare an analysis result with a measurement result and analyze it. It was comparatively good about the dynamic axial strain of small amplitude, but it was difficult as a result of past examination. Evaluation of the influence such as the shrinkage behavior of the filling concrete of CFT columns was always hindrances of the conversion to column axial force from column axial strain by the dead load. We performed an experiment to grasp shrinkage behavior of the filling concrete of CFT columns from such a background. Furthermore, We performed loading test and considered influence of the shrinkage of the filling concrete.

In this paper, an earthquake response analysis model based on seismic performance indices is proposed to evaluate actual seismic performance of public management apartment buildings appropriately. Damage ratio of buildings are calculated using this proposed model and observed seismic ground motions during the 1995 Hyogo-ken Nanbu Earthquake. As a result, the relationships between an index of seismic ground motion and calculated damage ratio of buildings show good agreement with vulnerability functions based on actual damage data of buildings in the 1995 Hyogo-ken Nanbu Earthquake. Through this study, it is pointed out that damage ratio of buildings could be overestimated, if load carrying capacity which has not been considered in the seismic design is not properly evaluated. Additionally, it is shown that the effect of slit on reinforced concrete wall has a big influence on the damage ratio of buildings.

A series of shaking table tests on a high-rise building are conducted in order to assess effects of retrofit using steel dampers. The specimen consists of a four-story steel frame and an upper substitute layers made of concrete slabs and rubber bearings. Steel brace dampers are attached to the steel frame, and modeled steel dampers are utilized for the substitute layers. Long-period ground motions and a design ground motion are used for the tests. Total input energies of the specimen reasonably correspond to the estimations of energy spectra. The deformations of specimen are reduced especially in the portion having dampers. In the steel frame, the energy is mostly dissipated in the steel brace dampers. The capacities of the steel brace dampers are estimated about ten times larger than the seismic demand in a strong long-period ground motion.

In this paper, analytical examinations have been carried out in order to understand the torsional input motion induced by foundation's shape and the use of composite foundation. Analytical models are divided into five general categories; L-shape foundation or triangle-shape foundation supported by identical piles, square shape foundation supported by different diameter piles or supported by different length piles, and square foundation with partially embedment. It is clarified that the difference of pile section and partial embedment influences a lot on torsional input motion while the effect of foundation's shape and difference of pile length is not so much.

In this paper, we analyzed the damage of reinforced concrete buildings due to the 1923 great Kanto Earthquake in the City of Tokyo based on the major two damage investigation reports. One is made by the Shimizu-gumi construction company, which is newly analyzed in this paper, and the other is well known report by the Imperial Earthquake Investigation Committee. As a result, the damage of RC buildings was clearly related with their building type and use, number of floors and distributed area. Detailed investigation on some damaged buildings revealed the situation of reinforced concrete buildings at that time, as well as the properties of damage investigation by a construction company. Microtremor observation and soil boring log collection were newly done at 53 sites of damaged buildings. Surface soil conditions obtained from H/V spectra of microtremor and drilling data were examined and shown to be related with reinforced concrete building damage. The difference of seriously damaged area of reinforced concrete buildings and wooden houses was observed which will be important aspect of seismic hazard distribution in the Tokyo city area.

Two inelastic devices, a collapse model of a wooden structure and a liquefaction model, are developed for repeatable experiments. This paper contains the outline and use of them. In the wooden model, rubber cords and magnets are installed not only for tying beams and columns, but giving restoring force and stiffness to the structure and keeping configuration of each part. In the liquefaction model, flushing system with a small pump demonstrates simplified liquefaction. Thanks to the portability as well as easy repeatable experiments of collapse and liquefaction arriving to inelastic ranges, these are useful for education of earthquake disaster mitigation.

We have been measuring the performance of plural buildings by mounting optical fiber sensors capable of measuring static and dynamic displacement on some columns of plural buildings in the process of being constructed, in order to grasp and verify their performance from the difference between the performance of actual buildings and their design performance. We analyzed the results of the measurement and reached the conclusion that measurement using optical fiber sensors is applicable to (1) evaluations of the performance of buildings, structural systems, and construction quality based on the analysis of the difference between the performance of actual buildings and their design performance, (2) feedback to future design, and (3) the estimation of the degree of damage to buildings after a disaster. In this paper, we describe particularly dynamic measurement results of the measurement we have conducted on two skyscrapers whose elevational shape is irregular, or regular, and describe the utility of the measurement system to suggest, and show future prospects.

In long-period ground motions, high-rise buildings are subjected to large cumulative deformations as well as large story drifts. Retrofitting with dampers may be one of the most effective solutions reduce such seismic responses. This study examines the influences of steel dampers partially installed into the lower part of high-rise buildings. A series of dynamic response analyses are conducted for typical steel high-rise buildings. A long-period ground motion is adopted whose energy spectrum has a peak amplitude at three seconds, and twenty-one story buildings and thirty-five story buildings are substituted by frame models. The results show that the total energy absorption of the dampers installed into forty-percent stories can be equivalent to that of the dampers installed into the whole stories. On the other hand, the maximum drift of the story located right on the lower part having dampers would become 1.4 times larger than those of the lower part.

本研究は, 脅威アピール研究の枠組みから, 小学生を対象とした防災教育が, 児童の感情や認知に変化を及ぼす可能性, および, これらの感情や認知の変化が, 保護者の防災行動に影響する可能性を検討した。135名の小学校5年生と6年生を対象に, 防災教育の前後, 3ヵ月後の恐怖感情, 脅威への脆弱性, 脅威の深刻さ, 反応効果性を測定した。また, 防災教育直後の保護者への効力感, 保護者への教育内容の伝達意図と, 3ヵ月後の保護者への情報の伝達量, 保護者の協力度を測定した。その結果, 教育直後に感情や認知の高まりが確認されたが, 3ヵ月後には教育前の水準に戻ることが示された。また共分散構造分析の結果, 恐怖感情と保護者への効力感は, 保護者への防災教育内容の伝達意図を高め, 伝達意図が高いほど実際に伝達を行い, 伝達するほど保護者の防災行動が促されるという, 一連のプロセスが示された。考察では, 防災意識が持続しないことを理解したうえで, 定期的に再学習する機会を持つこと, そして, 保護者への伝達意図を高くするような教育内容を工夫することが有効である可能性を議論した。

In this study, we observed the vibrations caused by the construction of a roadway tunnel excavated using the New Austrian Tunneling Method (NATM) in an urban area. We analyzed the resulting vibrations and disturbances and their effect on a high-voltage electron microscope (HVEM). The characteristics of the construction equipment, various construction tasks, wave propagation and attenuation in the soil, along with the transmission of vibration forces to adjacent buildings were also clarified. These findings were combined and the effects on the HVEM were examined to model vibration-induced disturbances. The accuracy of these findings was confirmed by comparing the results obtained with actual observations that were recorded later. The findings of this study are expected to enhance the ability to distinguish between the many factors involved in vibration-induced disturbances caused by equipment. The findings could also be applied to monitoring construction activities and predicting the effects of vibration-induced disturbances on high-precision equipment.

Considering the increased population and functionality of urban areas, we have studied the prediction of damages to and disaster mitigation strategies for urban areas which may be devastated when large disaster strikes. We have developed high-precision, high-resolution subsurface soil structure models in Chukyo Area including Nagoya city, by which strong ground motions are first predicted for every site of the area using a pseudo-empirical Green’s function method. Next, major damages are predicted based on earthquake response analyses of various structures such as energy facilities in reclaimed areas, industrial plants in alluvial plains, and high-rise buildings and ordinary school buildings in urban areas. We then have attempted to quantify disaster response capabilities of urban areas to set the target level for disaster mitigation countermeasures. Moreover, we have explained newly developed simulation tools for guiding individual residents to take disaster mitigation precautions by themselves.

Two dimensional long stroke shaking table is developed, which is available for a person to experience realistic earthquake shaking and building response. Indoor and outdoor shaking scene is projected in front of the cage and is synchronized with the shaking table. Input waves are simulated ground motions and building responses which are easily selected on the WebGIS maps. Small-sized shaking table is also developed, and observed responses and video images are available in the large shaking table experience. Such a series of devices and systems provides realistic shaking experience and is effective for promotion of disaster mitigation activities.

We installed the optical fiber sensor which could measure dynamic strain and static strain with high precision in order to identify difference with the result of analysis for structural design as a true building, and to specify the performance of the building.By the analysis of the measurement, building performance evaluation / structure system evaluation / construction quality evaluation can use it, and think that feedback to a future structural design, an estimate of the damage can use it again.By this report, we introduce technology to measure strain and technology to convert strain into stress and we show analysis until the present.

This paper proposes a new place-name classification table considering geographical features and soil characteristics, which helps interpretation of seismic hazard maps. This table is classified into two soil groups (stiff soil and soft soil) based on the origin of their Chinese characters. We select bus-stop name from many kinds of place-name. This reason is the following two points. Distribution density of bus-stop is almost evenly in the city, bus-stop name mostly remain past place-name. The validity of the new place-name classification table and bus-stop name is clarified through case studies on the three major metropolitan areas of Japan.

A portable microtremor observation and analysis system has developed for on-site evaluation of dynamic properties of buildings and ground. The system can evaluate the soil period from the H/V spectrum and the building period and damping using the Random Decrement (RD) method. The software is designed with real-time data processing and easy operation using a graphical user interface (GUI). All of the system components such as sensors, a touch-panel PC, butteries and cables are packed in a carry case. The system is useful especially for easy evaluation of existing buildings with possible resonance which are important for structural design of seismic retrofit.

The present study describes the important factors (period, duration, and intensity) involved in evaluating input ground motion and structural response for the design of long-period structures such as high-rise buildings and base-isolated buildings. First, the fundamental dynamic properties of high-rise buildings are explained based on the results of newly introduced vibration observations programs. Next, the distribution of the predominant period and duration of seismic ground motion within the Nobi Plain, one of the largest sedimentary plains in Japan, is discussed with respect to the possibility of resonance of long-period structures. Finally, we introduce a recently developed long-stroke shaking table that is intended to convince structural engineers and building owners to take adequate countermeasures against large floor response in high-rise buildings because of resonance.

In this paper, we research a conventional evaluation method of soil springs in the dynamic soil-structure interaction analysis of buildings with embedment foundations. First of all, the bottom element and the side elements are decomposed from the embedment foundation and the dynamic interaction characteristics that each element possesses are examined. The estimation method developed by WEN and Fukuwa(2006) are applied to this examination. Based on the above results, it is mentioned that the soil spring of the embedment foundation which is composed with the impedance of both side and bottom elements is overestimated. Finally, we discuss impedance evaluation methods in the limit strength method and the sway-rocking model with embedment.

This paper describes a newly developed information system dedicated to promoting the earthquake disaster mitigation practices of residents themselves. The system is based on a type of simulator that presents realistic personal disaster scenarios, related to actual seismic hazards, in order to help each resident gain awareness of his/her own hazard level, and to comprehend the need and methodology for making preparations. The simulator is built around a web-based online geographic information system known as WebGIS, and integrates a series of subsystems that provide a number of features including a highresolution hazard map system capable of creating three-dimensional birds-eye overviews, a system for evaluating earthquake ground motion at a specific location, as well as a system for simulating earthquake effects and the possible collapse of a wooden house at a site (including the risks of falling indoor furniture). Furthermore, in order to provide comprehensive information on seismic hazards and disaster mitigation, various related programs that utilize online systems (including WebLog, Wiki and other interactive interfaces) have been incorporated. The applications of these systems to community disaster mitigation workshops in Nagoya City are described, together with the newly constructed web systems and education facilities of the Aichi Prefectural government.

As seismic retrofit for Aichi prefectural office building, base isolation retrofit method was recognized by Aichi prefectural assembly and we started further study for basic design. We had to budget the seismic retrofit cost for coming year and we investigated important matters for cost such as building foundation level, necessary volumes of soil improving and so on. And we had to decide seismic criterion of retrofit building. We had to study about tender method in addition. This report is summary of basic design.

By use of a newly developed network connected vibration measuring system which is suitable for continuous observation at construction sites, dynamic characteristics of high-rise buildings and their change during construction are discussed. Hundreds of ambient vibration data and several seismic response records were obtained at two neighboring high-rise buildings in approximately twenty months of construction. Observed response characteristics, estimated natural periods and damping ratios are shown with the change of building height under the same soil and foundation condition. Characteristics of higher modes and soil-structure interaction effect are also discussed. By use of forced and ambient vibration data, amplitude-dependent characteristics are clearly displayed as a relation with the velocity response which is proved to be highly correlated with the average deformation angle of stories.

Dynamic properties evaluation by microtremor observation was conducted for valuable modern historical buildings in the architectural museum “Meiji mura”. The estimated natural frequency and damping ratio of all the buildings are accumulated into database together with the structural and historical features of the building. Surface layer characteristics are examined at many points in the museum, and the area of filled ground is clearly shown. The earthquake observation is also conducted at three important buildings. Such observation and database are important for planning seismic retrofit of these buildings.

Web based e-learning system is developed for the education of structural dynamics for University students and for the dissemination of disaster prevention for the society people. This system shows the dynamic response of the 2-dofs lumped mass system. It is possible to easily make a virtual experiment on a web browser. User can produce the seismic ground motion by dragging the ground with the mouse right and left on the browser. The ground can also be shaken by the observed earthquake wave in the database. User can freely make an experiment using various variables. The students easily understand the dynamic phenomena of structure through the combination of formulation, graph, and the experiments using this software.