调谐惯容电磁阻尼—摩擦摆组合隔震体系的需求导向设计方法研究

DEMAND-ORIENTED DESIGN METHOD OF THE HYBRID-ISOLATED BUILDING EQUIPPED WITH TUNED INERTER ELECTROMAGNETIC DAMPER AND FRICTION PENDULUM BEARING

  • 摘要: 为解决强震下摩擦摆基础隔震结构隔震层位移需求过大的问题,本文提出一种调谐惯容电磁阻尼—摩擦摆组合隔震体系(TIED-FPB)。考虑FPB和电磁阻尼的非线性特征,将FPB隔震结构简化为两自由度体系,建立该组合隔震体系的运动方程。借助FPB和电磁阻尼的随机等效线性化模型构建等效TID-2DOF体系。基于白噪声激励下隔震层位移的"H" _"2" 范式推导等效TID设计频率比和阻尼比的闭合解。结合复振型分析、复完全平方组合(CCQC)和随机振动分析求解等效TID组合隔震体系在功率谱密度激励下隔震层位移和阻尼相对速度的最大值。给定隔震层位移需求目标,通过迭代更新策略得到等效TID的设计质量比。由TID中黏滞阻尼的相对速度最大值和阻尼系数确定TIED中电磁阻尼的特征速度和特征阻尼系数,进而实现TIED的需求导向设计。为验证本文所提方法的合理性和TIED-FPB组合隔震体系的抗震性能,在OpenSees中构建电磁阻尼材料模型,根据规范设计谱选择44条地震动对一7层隔震Benchmark模型进行非线性时程分析。结果表明:与FPB隔震结构相比,TIED-FPB组合隔震体系的隔震层位移减小25.8%,加速度响应的鲁棒性提升32.3%。

     

    Abstract: To address the risk of the excessive displacement demand of the isolation layer in the friction pendulum bearing (FPB) based isolation system subjected to severe earthquake excitation, a hybrid isolation system with tuned inerter electromagnetic damper and FPB (TIED-FPB) is proposed in this paper. Considering the mechanical nonlinearity in FPB and electromagnetic damping, the governing equation of the TIED-FPB system is constructed by simplifying the base-isolated structure into a two-degree-of-freedom (two-DOFs) system. By virtue of the stochastic equivalent linearization model of FPB and electromagnetic damping, the equivalent TID-two-DOFs system is constructed. The closed formula of the design frequency ratio and damping ratio of the equivalent TID is derived by considering the H2-norm of the basement displacement response under the white noise excitation. In combination with the complex mode analysis, complex complete quadratic combination (CCQC), and stochastic vibration analysis, the maximum responses of the basement displacement and the relative velocity of viscous damping in TID were approximated when the isolation system subjected to the power spectrum density excitation. Given the displacement demand target of the isolation layer, the mass ratio of the TID is obtained through the iterative update strategy. The critical velocity and critical damping coefficient of electromagnetic damping in TIED are determined from the maximum relative velocity and the equivalent damping ratio of the damping in TID, further realizing the demand-oriented design of the TIED. To verify the feasibility of the proposed optimization method and the seismic performance of the TIED-FPB isolation system, a new uniaxial material for mimicking the electromagnetic damping was added in OpenSees software, and 44 seismic ground motions were selected according to the standard design spectrum to perform the nonlinear time history analysis of a 7-story seismic isolation benchmark model. The time history results show that compared with the FPB-based BI system, the proposed TIED-FPB reduces the displacement response of isolation by 25.8% and improves the robustness of acceleration response by 32.3%.

     

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