In 2011, Great East Japan Earthquake that is the largest earthquake ever observed occurred. The earthquake had large energy, long duration time and many aftershocks. Huge tsunami caused nuclear accidents. At present, a large number of nuclear power plants in Japan have not been operated yet. Then the base load power in Japan was shifted from nuclear power to coal-fired thermal power. Therefore it is very important to improve aseismic performance of coal-fired thermal power plants. Boiler structures in coal-fired thermal power plants are generally high-rise structures. In addition its combustion temperature is very high, so boilers are simply suspended from the top of the support structures in order to allow thermal expansion. Therefore boilers easily vibrate. In order to suppress vibration of boilers during earthquakes, stoppers are set between boilers and support structures. The stoppers are made of steel, and dissipate vibration energy by plastic deformation. However aseismic requirements for thermal power plants against large earthquakes having large numbers of repeat counts have been increased. Then authors have developed a vibration control damper for coal-fired power plants. The damper is set instead of conventional stopper made of steel, and it is able to perform in earthquakes with relatively large numbers of repeat count. Construction of the damper is similar to oil dampers, but inner fluid is viscous fluid. In this paper, a seismic response analysis using an analysis model of a boiler structure is conducted. The analysis model has plural stoppers or plural dampers. The response analysis result is arranged to investigate lifetime of the stoppers or the dampers. The accumulated plastic displacement of each stopper or damper is used for the evaluation. As a result, it was confirmed that the proposed damper has high durability compared with conventional stopper made of steel.

In 2011, Great East Japan Earthquake that is the largest earthquake ever observed occurred. The earthquake had large energy, huge tsunami, long duration time and many aftershocks. Devastated area needed retrieval and revival. However, when electric power was lost, the retrieval delayed. It is necessary to improve seismic proof construction for power plants. In this paper, authors proposed vibration control by adding dampers for coal-fired power plant and developed it. Fundamental analysis and component test of the damper were conducted. As the analytical results, characteristic of the damper was searched what kind of performance is more effective for the coal-fired power plants. In the component test, actual scaled prototype of the developed damper was produced and its performance was checked by loading test. As the test results, suitable characteristic of the damper was searched by the analysis. Finally, authors proposed two analytical methods of the developed damper.

This paper deals with the evaluation of aseismic reliability of actual boiler plant structures in conjunction with seismic ties, installed between the boiler and the support structures. Proof tests were conducted with a coupled model using a large-scale shake table which verified that the ties acted as energy-absorbing devices against severe earthquakes. Since recent boiler structures are designed based on dynamic response analysis considering the boiler-structure interaction and the effect of energy dissipation of the ties, it is necessary to verify the accuracy of simulation methods. In view of this, the numerical models of the ties are discussed in post analysis. As a result of the post analysis, it is confirmed that (1) seismic ties of existing boiler plants designed by dynamic analysis provide sufficient durability, and (2) the support structures designed by conventional methods have enough aseismic reliability.

A purpose of this study is an improvement of seismic proof construction for power plants to supply power stably at an emergency. At present, the most common type of power generation in Japan is thermal. In particular, coal-fire becomes base load power. A proposal of this study is that boiler structure is applied vibration control. The way is that a damper used viscous fluid is set instead of stopper between the boiler and the support structure. However, inside temperature of the boiler structure is higher than the environment of the general because it uses burning of coal and steam. Therefore, this paper shows that the damper has applicability for the environment of the boiler structure. Then it is necessary for structures to endure earthquake with long duration and long period component in Japan. The 2011 off the Pacific coast of Tohoku Earthquake had the largest energy in history of Japan with them. The damage occurred not only in Tohoku but also in far Tokyo and Osaka. Moreover, it is predicted that large earthquakes with them at the south Pacific coast of Japan occur. This paper shows that the developed damper is effective in earthquake with these characteristics by analyses and component tests.

The 2011 off the Pacific coast of Tohoku Earthquake had the largest energy in recorded history of Japan and it caused severe damage. The damage occurred in a large area as well as the Tohoku in various ways. Electric power was one of them. Therefore, rolling blackouts were carried out with lack of power supply in a part of the East Japan. The electric power is indispensable because restoration activity advances at a disaster area. Moreover, Japan is the highly advanced information society. The steady supply in case of the emergency is expected while a large earthquake whose seismic center is Nankai trough is predicted. Therefore, it is necessary to improve seismic proof construction of power plants. At present, the most common type of power generation in Japan is thermal. Even among them, coal-fired power plants become base load power. A proposal of authors is application of vibration control using damper to boiler structures. This study shows the effects while the earthquake with long period component and long duration was used. It is concerned that the damage of the high-rise structure like boiler structure becomes critical by the long period component. Moreover, the durability of the structures and devices is required higher than conventional by the long duration. In this study, authors developed a damper to use for vibration control of the boiler structure and showed the analytical and experimental results of applicability for the earthquake with long period component and long duration of it.