摘要 本文主要在研究利用近似公式來計算隔震樓房的系統反應，文中共提出五種近似公式，而公式推導過程中主要是利用系統的第一模態加以模擬，就可以直接將多自由度系統轉換成多個單自由度系統，此種作法的優點為第一模態是由質量與勁度矩陣直接求得而與阻尼矩陣無關，因此，並不會有像模態疊加法，必須對組尼加以假設的問題存在。 根據研究結果顯示，隔震樓房系統中，第二及第四種方法所計算出來的結構反應皆相當準確；如果在計算一般樓房時，第二種方法優於其他方法；而第一及第三種方法的計算結果會有放大效果，造成較大的誤差。 ABSTRACT This paper is mainly studying how to use similar formula to calculate the response of the system of the isolation building. There are five different kinds of similar formula. The process of the ratiocination of the formula is mainly using the first mode of the system to stimulate. Therefore we can directly transfer the MDOF into many SDOF. The advantage of this method is that the first mode was directly calculated by mass and stiffness matrix. It has nothing to do with the damping matrix. Therefore, it will not be like mode – superposition method, which is necessary to assume the form of damping. According to the result of the study, in the system of isolation building, the response of the structure calculated by the second and fourth formulas are very accurate. When calculating general building, the second formula is better than the other methods. And there will be a magnifying effect when using the first and third methods, which causes a bigger error.