设置间隙式SMA隔震支座的钢筋混凝土框架结构抗震性能分析
Seismic Performance Analysis of Reinforced Concrete Frame Structures With Gap-SMA Isolation Bearings
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摘要: 隔震支座除了保护上部结构, 还应当能控制结构在地震下的最大位移和残余位移.为此, 提出了由预松弛的形状记忆合金(shape memory alloy, SMA)棒和铅芯橡胶支座(lead rubber bearings, LRB)组成一种新型隔震系统, 即间隙式SMA隔震支座.首先, 简述了间隙式SMA LRB的构造及工作原理.其次, 进行了间隙式SMA支座的性能试验.最后, 基于OpenSees, 以一个5层框架结构为例, 对比了有无隔震支座结构的地震响应, 探讨间隙大小对减震效果的影响.弹塑性时程分析结果表明, 该隔震支座在小震时仅拥有橡胶支座提供的较低刚度, 上部结构表现出理想的地震响应.随地震动强度增大, SMA进入工作状态, 提高了支座的水平刚度, 并提供一定的自复位功能, 有效地减小结构残余变形.该装置具有较好的自复位、限位和耗能能力.Abstract: In addition to protecting the superstructure, the isolation bearing should also be able to control the maximum displacement and the residual displacement of the isolation layer under earthquakes. Toward this end, this paper proposed an innovation type of lead rubber bearings (LRB) incorporating gap shape memory alloy (gap-SMA) bars, namely gap-SMA lead rubber bearings (gap-SMA LRB). First, the working principle of the gap-SMA LRB was briefly described, followed by physical tests on gap-SMA bearing specimens. Based on OpenSees, a case study focusing on a 5-story medical building was subsequently conducted, where two types of structure system, namely, fix-based system and gap-SMA LRB system were compared. Besides, the influence of the gap length on the shock absorption effect was analyzed. The results of elastic-plastic time history analysis show that such isolation bearing only has the lower stiffness provided by the rubber bearing during slight earthquakes, and the superstructure exhibits an ideal seismic response. With the increase of the ground vibration intensity, SMA takes effect, increases the horizontal stiffness of the bearing, and provides a certain self-centering ability, effectively reducing the residual deformation. This device possesses prominent self-centering and energy dissipation capacity.