中文摘要：

根据现行的《建筑抗震设计规范》（GB50011—2001），结合2个工程实例，通过建立空间三维有限元模型分析了钢结构跃层加层结构的动力特性，并分别用振型分解反应谱法和时程分析法对分离式和整体式外套框架跃层加层结构进行了地震反应分析，比较了2种结构的地震响应和抗震性能。结果表明：整体式跃层加层结构所受地震力较大，层问剪力峰值持续时间较长，衰减较慢。所得结论可为具有类似加层结构的抗震设计提供参考。

英文摘要：

According to the actual Code for Seismic Design of Building （GB 50011--2001） and combining with two engineering cases, the dynamic characteristics of adding extra-floors spanning existing building with steel structure were ana and the seismic responses of the separated an response spectrum method and time history ana zed through making 3-D finite element model, integral coat framing were obtained by using sis method of vibration mode. The results show that the seismic force of adding extra-floors spanning existing building with steel structure is bigger, and the time of top values of shearing force between layers is longer, and the reducing is slower. The seismic responses and seismic behaviors of two kinds of structures were compared. The conclusion can be served as the references of such structure design.