塔状鋼構造物の動特性に関する実験的研究

Abstract

This paper presents the distribution properties of the shear forces of steel tower structuressubjected to earthquakes from the results of shaking table experiments.Dynamic properties of the steel tower itself were initially examined by using a rod model, alatticed tower model and the models with additional lead weights which were installed at differentlocations of the original models, so as to generate various shear force distributions. From the re-sults, the shear forces of models predominantly viblating in the fundamentary mode were greaterthan which specified by the latest Japanese building code, at the middle height part of the mode.Whereas, model predominantly viblating in the secondary mode showed similar shear force distri-butiona as the building code, but the relative response of the top of the model was greater, whenthe mass of the top was smaller.Secondary, a coupled model consisted of the towers and cables simulated actual power trans-mission tower lines was tested in order to assess the effect on dynamic response of biaxial excita-tions. From the results, it has been shown that dynamic response of individual towers are re-markably influenced by the stiffness of the cables at the longitudinal excitation, whereas the re-sponse at the transverse direction was smaller caused by damping effect of cables. And thus, aseismic safety of actural power transmission towers subjected to the longitudinal excitationsassessed by taking account of the existence of electric lines.