远场地震动长周期特性对基础隔震结构地震响应影响研究

Influence of long-period characteristics of far-field ground motions on seismic responses of base isolated structures

与普通强地震动相比,长周期地震动的低频分量丰富,对长周期结构影响显著。隔震结构作为一类具有较长自振周期的结构,其在长周期地震动作用下的动力行为值得研究。选取远场长周期地震记录和远场普通地震记录作为外部激励,以某基础隔震结构作为研究对象,研究了远场地震记录的长周期特性,及其对隔震层和上部结构地震响应的影响。研究结果表明:远场地震动长周期特性对结构地震响应的影响显著,远场长周期地震记录下结构的地震响应明显大于远场普通地震记录,在隔震结构设计中应考虑其不利影响;地震动功率谱与结构地震响应之间存在明显联系,应进行深入研究。研究结果可为长周期地震动作用下隔震结构的抗震设计提供参考。

Compared with ordinary strong seismic ground motions, the low frequency components of long period ground motions are abundant, and these can cause great impact on those structures which have long natural vibration period. As a kind of long period structures, the dynamic behavior of base isolated structures under long period ground motions should be studied. Far field long period ground motions and ordinary ground motions were used as seismic input, a base isolated structure was used as research object, the long period characteristics of far field ground motions, and its influence on seismic responses of isolation layer and supper-structure were studied. The resuits show that the long period characteristics can cause significant effect on structural seismic responses, the seismic responses under long period ground motions are greater than those under ordinary ground motions, and these negative influences should be considered in the design of isolated structures. In addition, the relationship between ground motions power spectrum and seismic responses of base isolated structures is obvious, and it should be studied further. The achievements in this paper can provide references for the seismic design of isolated structures under long period ground motions.