2022 年 88 巻 908 号 p. 21-00389
For the past several years, large scale earthquakes happened. A lot of industrial facilities were damaged. For example, a lot of power plants were stopped in The 2011 off the Pacific coast of Tohoku Earthquake or The Southern Hyogo prefecture earthquake in 1995. These earthquakes had larger acceleration level than the seismic design level. Therefore, the earthquake proof measures are required. In this study, earthquake proof effect of the beam with initial torsion is focused. The design guidelines for application to the thin-walled beam with initial torsion structure is proposed. The thin-walled beam with initial torsion is modelled by FEM and calculated. The static and dynamic loading characteristics of the actual beams are compared with the analytical results to verify the validity of the analysis. The comparison result of analysis and experiment shows that the FEM analysis of the beam element is valid up to 0.23 aspect ratio. The analysis was used to clarify the static characteristics, for example, stiffness or displacement, and dynamic characteristics, for instance, frequency or vibration mode, under the conditions of the aspect ratio and total torsion angle of the beam. By the time history analysis, it was shown that the vibration response changed by the initial torsion, and that it was possible to reduce the acceleration response. In order to evaluate the response reduction effect, the acceleration response for the condition of the aspect ratio and total torsion angle of the beam was analyzed. And the response reduction map is proposed. Using this map, it is possible to estimate the advantage of the initial torsion effect for the response reduction effect in a simple manner.
