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This paper proposes an experience-based lecture style that offers dual-scale experiments in combination. Lectures for vibration engineering were designed based on the proposed style and offered to undergraduate students. In the proposed style, experiments on free vibration on a seismic building for second-year students and advanced vibration control using an effective device for fourth-year students are examined in combination. The lecture style trials were repeated twice, once each in 2015 and 2016, with about two hundred second-year students; the students felt the free vibration of the five-story building which had a 6,100 ton weight inside and witnessed the mechanism of the base-isolated layer. To follow the demonstration steps, we developed an experimental device. The experimental device is composed of a vibration component corresponding to a building, and a motor cart with a handle corresponding to the ground. These are connected via a linear actuator that can exert one-dimensional force on the vibration component as a function of the input voltage. In the lectures conducted in 2017 and 2018, the students oscillate the cart and observe the motion of the vibration component. In addition, the virtual reality cameras for offering students a visually rich experience attracted students' interest. The questionnaire results showed that almost all of the students valued the lectures as useful. Since most of the students answered that the combination of the large-scale demonstration and scale-down experiment was useful, the proposed lecture style achieved the expected overall goals.

Characteristics of long-period seismic ground motion and response of tall buildings are investigated in this paper to promote earthquake proof countermeasures considering the damage caused by the 2011 Tohoku earthquake. 3D finite difference method and the reciprocal theorem are used to examine the effect of sedimentary basin structures on seismic wave amplification. Natural period and damping of tall buildings are evaluated by ambient vibration tests and earthquake response observation during construction or demolition of the buildings. The effects of dynamic soil-structure interaction on response amplification of tall buildings are confirmed applying wave propagation theory to a continuum building model. Finally, a newly built base-isolated building with an isolated rooftop laboratory is introduced for full-scale long-period shaking experiment by installing actuators and jacks. Experience of long-period shaking in the building is also available with virtual reality view of indoor damage, which is effective for promotion of seismic countermeasures such as fixing furniture and safe evacuation.

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.

Listening to a sound representing ground motion is valuable to understand an earthquake intuitively compared with only seeing a waveform. In this paper, we propose a new method to make a sound of earthquake, in which several rules different from existing methods are used. In our new method, a sound of earthquake is generated by modifying the frequency information of generating function based on the theory of symmetric Fourier analysis. Applying the method to the JMA Kobe seismogram in 1995 South Hyogo Prefecture Earthquake and predicted waveform at Sannomaru, Nagoya, in future Tokai and Tonankai earthquake, three features of the sound generated by this method are confirmed: the sound has same duration time as the seismogram, high sound is heard when the seismogram has high frequency, and loud sound is heard when the seismogram has large amplitude.

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。