Parameters Optimization for Seismic Isolation Layer in Double-tower Structure on Vehicle Depot Upper-cover
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摘要: 城市大平台建筑上盖结构隔震技术设计受到广泛关注,有必要进一步研究这类结构体系的隔震技术原理并对其隔震参数进行优化。本文以车辆基地上盖隔震双塔结构为研究对象,首先基于振型叠加理论建立了结构简化计算模型,采用随机振动分析方法,建立了上盖塔楼结构加速度响应及基底剪力均方值显示表达式;其次,利用遗传算法,提出了以结构响应最小为优化目标的隔震层刚度和阻尼比优化设计方法;最后,采用MATLAB开展了车辆基地上盖隔震双塔结构隔震层参数优化分析,得到了隔震层的优化设计参数。研究结果表明,考虑下部结构一阶振型参与系数的简化模型可保守计算结构的基底剪力响应;当以上部结构绝对加速度响应最小为优化目标时,体系最优频率比取最小值0.05,隔震层阻尼比取值在0.3~0.5;当以体系基底剪力方差最小为优化目标时,随体系质量比的增加,体系最优频率比取值逐渐减小,隔震层阻尼比取值逐渐增大。实际工程结构设计中建议采用多目标优化设计方法。Abstract: Seismic isolation technology for the upper cover structure of large urban platform buildings has garnered significant attention. To enhance this technology, it is essential to further investigate the seismic isolation mechanisms of such structural systems and optimize their parameters. This study focuses on an isolated double-tower structure on a vehicle depot upper cover as the research object. A simplified calculation model of the structure was first established based on mode superposition theory. Using random vibration analysis, expressions were derived for the acceleration response of the upper tower structure and the root mean square value of the base shear force. Next, an optimization method for the isolation layer’s stiffness and damping ratio was proposed, aiming to minimize structural responses through the use of a genetic algorithm. Finally, MATLAB was employed to conduct the optimization analysis of the isolation layer parameters for a practical double-tower structure on a vehicle depot upper cover, leading to the determination of optimal isolation layer design parameters. The results show that the simplified model, which accounts for the participation coefficient of the first-order mode of the lower structure, can conservatively estimate the base shear response of the system. When minimizing the absolute acceleration response of the upper structure, the optimal frequency ratio is found to be 0.05, with the damping ratio of the isolation layer ranging between 0.3 and 0.5. When the objective is to minimize the variance of the base shear at the system level, the optimal frequency ratio decreases and the damping ratio increases as the system’s mass ratio increases. The study recommends using a multi-objective optimization approach for practical engineering structural design.
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表 1 楼层质量和刚度分布
Table 1. Distribution of story mass and stiffness
结构 楼层 质量/kg x方向刚度/(kN·m−1) y方向刚度/(kN·m−1) 下部结构 1 2.564×107 18.9×106 21.6×106 2 2.033×107 19.6×106 23.7×106 T1塔楼 4 0.102×107 1.57×106 2.07×106 5 0.102×107 1.18×106 1.57×106 6 0.102×107 1.06×106 1.43×106 7 0.102×107 1.02×106 1.38×106 8 0.102×107 0.99×106 1.34×106 9 0.102×107 0.97×106 1.30×106 10 0.098×107 0.92×106 1.23×106 11 0.094×107 0.77×106 0.97×106 12 0.094×107 0.77×106 0.93×106 13 0.094×107 0.73×106 0.84×106 14 0.089×107 0.58×106 0.62×106 表 2 简化三质点系模型计算参数
Table 2. Computation parameters of simplified three lumped mass model
质量/kg 刚度/(kN·m−1) 阻尼系数/(kN·s·m−1) m1 m2 m3 $ k_{{\mathrm{eq}}}^{} $ $ k_{{\text{ur}}}^{\text{b}} $ $ k_{{\text{ul}}}^{\text{b}} $ $ c_{{\mathrm{eq}}}^{} $ $ c_{{\mathrm{ur}}}^{\mathrm{b}} $ $ c_{{\text{ul}}}^{\text{b}} $ 3.13×107 1.20×107 1.20×107 1.04×107 4.89×104 4.89×104 6.75×104 1.05×104 1.05×104 表 3 结构首层及隔震层的地震响应
Table 3. Seismic response of the first floor and isolation layer
楼层 响应 地震波激励 白噪声激励 无控结构 fopt=0.56 f=0.05 f=0.2 无控结构 fopt=0.56 f=0.05 f=0.2 首层 绝对加速度 0.97 1 1.06 1.01 0.96 1 1.09 1.02 层间位移 0.99 1 1.13 1.03 1.02 1 1.08 1.02 剪力 1.04 1 1.11 1.02 1.07 1 1.04 1.01 隔震层 绝对加速度 1 0.86 0.18 0.66 1 0.85 0.19 0.63 层间位移 1 2.16 13.7 5.76 1 2.13 31.55 5.15 剪力 1 0.91 0.11 0.54 1 0.85 0.14 0.39 -
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