基础隔震是通过在结构物与基础间设置隔震装置来延长结构自振周期并增大结构阻尼,从而阻止地震能量向上部结构传递以减小结构地震响应的一种技术手段。采用天然橡胶支座、铅芯橡胶支座、弹性摩擦滑板支座加阻尼器的组合基础隔震系统可以充分发挥不同减隔震器的特性并控制支座变形,从而达到良好的隔震效果。通过高烈度区乙类建筑工程实例,阐述了组合基础隔震系统的设计方法、支座选择与布置原则,以及设计过程中控制参数的验证。时程分析表明,组合基础隔震系统可以有效减小结构的地震响应;罕遇地震作用下,结构顶层X,Y向加速度响应可分别减小66.6%和73.6%;结构底层X,Y向层间位移角可分别减小65.2%和64.2%,剪重比可分别减小62.2%和64.3%。
The base-isolation technique, setting isolation devices between basement and superstructure, could prolong the vibration period of isolated structure and increase structural damping to prevent the quake motion transfer from ground to superstructure, thus reducing the responses of structure subjected to earthquake. A combined base-isolation system composed of natural rubber bearings, lead rubber bearings, elastic sliding bearings and viscous dampers was introduced. The combined base seismic-isolation system can take full advantage of properties of different isolation dampers to control bearing displacement to achieve good seismic isolation effect. Based on B-class practical building engineering in high seismic precautionary intensity region, the design method, selection and arrangement principles of bearings and verification of design parameters of the combined base seismic-isolation system were discussed. Time-history analysis shows that the combined base seismic-isolation system can effectively reduce seismic response of the structure ; Under the rare earthquake, roof acceleration responses are reduced by 66. 6% and 73.6% respectively for X and Y directions, drift ratios of bottom layers are reduced by 65.2% and 64.2% respectively for X and Y directions, and shear-to-weight ratios of bottom layers are reduced by 62.2% and 64.3% respectively for X and Y directions.