基于平扭耦联局域共振有限周期性结构的储液罐隔震机制

Storage tanks are widely utilized in many industries and their earthquake damages are likely to induce significant loss in casualties, property and environment. Traditional base isolation by means of reducing natural frequencies is considered effective in protecting tanks and remains dangerous in increasing liquid sloshing, larger response under low frequency earthquakes and unprotect against vertical quakes, which can be solved by adopting periodic foundation. Periodic foundation is capable of filtering and attenuating earthquake energy within the frequency range of superstructures...A 3-stage research is proposed to develop economic finite periodic isolation mechanism for storage tanks with varying frequencies:..1) To develop novel locally resonant periodic element by introducing both an eccentric mass-spring system aiming at translation-rotation coupled local resonance and two bumpers aiming at energy absorption during local resonance, then to investigate vibration performance of the proposed periodic element, the attenuation zone feature of the proposed periodic foundation and threshold condition for the fusion of the lowest two attenuation zones;..2) To investigate the achieved attenuation performance of the proposed finite periodic foundation under earthquakes, and to develop an equivalent simplified model of the proposed periodic element subjected to earthquake waves;..3) To study based isolation performance for storage tanks with the proposed finite periodic and to develop corresponding optimal design theory, then to give relevant design guidelines.

储液罐在各行业广泛使用，其震害易造成重大人员财产和环境损失。传统减小自振频率的隔震技术被认为是有效的储液罐抗震安全保护措施，但尚存在可能加大液体晃动、在低频地震作用下结构反应易加剧和难以竖向隔震等安全隐患。采用选择性滤波的周期性基础隔震技术，既可对覆盖上部结构自振频率的频率范围进行地震波滤波衰减，又可消除上述隐患。..本项目分三个阶段系统研究适合于储液罐自振频率因液面高度变化而大幅度变动的特点且高效经济的有限周期性隔震机制：..1) 采用“平转耦合局域共振”的偏心质量－弹簧系统和“局域共振缓冲”的缓冲器，提出新的局域共振单元并构成周期性基础，研究该单元的振动性能、该周期性基础的衰减域特性及其低频衰减域融合的门槛条件；..2）研究所提有限周期性基础对地震波的衰减规律，建立所提局域共振单元在地震波作用下的等效简化模型；..3）研究所提周期性基础对储液罐的隔震性能和最优设计理论，并提出设计建议。

周期性结构的带通特性使得将其作为隔震基础时，可有效地适用于储液罐自振频率因液面高度变化而大幅度变动的隔震问题。已有工作对周期性基础的隔震机制的研究尚不充分。本项目以简化分析模型和有限元模型结合试验开展了三方面研究：..1) 基于平转耦合局域共振和局域共振缓冲，优化实现了转动惯性放大机制和局域惯容共振机制，并提出了相应的新型周期性基础，通过参数分析及优化实现了低频宽带的衰减域；..2) 揭示了上部结构-周期性基础耦合作用的影响以及有限周期性基础的隔震机制，提出了竖向隔震周期性基础的可行方案并验证了其隔震性能；..3) 针对储液罐应用需求，提出了周期性基础隔震性能优化设计方法，研究了地震作用下土-周期性基础-结构相互作用并验证了相应的隔震有效性，提出适用于新型局域共振单元的新型阻尼器并研究了其低周疲劳性能。