Nonlinear dynamic analyses on the seismic response of reinforced concrete chimneys are carried out. An existing and a new design methods are applied to the design of the model structures. An existing design is equivalent to the current seismic standards in Japan, which is based on the allowable stress design, whereas the new design adopts capacity design concept where two plastic hinges are assumed at the mid-height and the bottom of the structure to protect RC chimneys from a collapse subjected to extremely strong ground motions. It is revealed that the extent of plasticity and location of yielding sections are varying drastically by the natural periods of the chimney and the predominant periods of the ground motions if the existing design are applied. So ductile detailing is necessary for all the region along the height. It is also revealed that the discontinuity of flexural strength is quite critical and sometimes results in unintended concentration of nonlinear deformations. On the other hand, the new design based on capacity design approach is found to have advantages in reducing the uncertainty of the non-linear responses and reducing maximum moment in the most part of the chimney, which ensure elastic response except the two potential plastic hinge zones. It may result in bringing the reduction of longitudinal reinforcements as well as eliminating the necessity of ductile detailing in the other elastic response region.%本論で得られた主な結論を以下に示す。（1）現行の告示の設計用応力によって設計される煙突は，煙突の高さや地震動の卓越周期によって曲げ降伏する位置や損傷範囲に影響があった。高さ63メートルの正方形断面を有する煙突を対象とした解析から，入力波が短周期で高次モードの振動が卓越する場合，煙突の全高さの約1/2Hより上部で曲げ降伏が発生したが，入力波が長周期で1次振動が卓越する場合は煙突の最下部及び高さの約1/2Hより下部で曲げ降伏が発生することがわかった。
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