【作者】 吴学淑；

【导师】 黄鼎业； 王翠坤；

【作者基本信息】 同济大学 ， 结构工程， 2008， 博士

【摘要】 本文以平面不对称高层建筑结构的被动耗能减震控制研究为核心,从耗能减震高层建筑结构地震响应计算、基于性能的耗能减震设计和阻尼器在不对称结构中的优化分布三方面进行一系列相关联的研究。主要内容包括:(1)阻尼器参数分析。分析阻尼器参数对单自由度体系振动响应的影响。通过参数分析,比较粘滞阻尼器和粘弹性阻尼器对单层不对称结构复模态参数的影响及减震效果。(2)基于改进Ritz法的非比例阻尼高层建筑结构的地震响应计算。改进Ritz法采用基于外荷载空间分布的Ritz向量和基于外荷载频率的Ritz向量。其中,基于外荷载空间分布的Ritz向量用Lanczos法形成;基于外荷载频率的Ritz向量则用外荷载主频的平方进行特征值平移后,再用Lanczos法形成。用改进Ritz法的Ritz向量对结构动力方程进行线性变换,之后采用拟力实模态法对线性变换后的耦联动力方程进行迭代求解。(3)基于性能的耗能减震设计。本文提出两种基于性能的抗震设计方法:①直接基于位移的耗能减震设计方法。性能目标用层间位移角表示。先将多自由度体系等效成单自由度体系,之后依据位移反应谱确定单自由度体系在已定水准地震动下满足目标位移要求所需的总阻尼比,该阻尼比可以近似认为是多自由度体系满足性能要求所需的总阻尼比,继而确定阻尼器的附加等效阻尼比和相应的阻尼系数。直接基于位移的耗能减震设计方法适用于对称结构;②基于多模态的耗能减震设计方法。基于多模态的设计方法将结构的性能指标用多阶模态表示,引入模态等效单自由度体系的最大位移之比,将结构的性能指标表示成关于第1阶模态等效单自由度体系的最大位移的函数,并由结构的性能目标值确定第1阶模态等效单自由度体系的允许最大位移,继而根据位移反应谱确定第1阶模态的阻尼比,确定附加阻尼比及阻尼系数。计算阻尼系数给各阶模态提供的等效阻尼比,依据阻尼比修正最大位移之比和模态的相关系数,进行迭代计算直到阻尼比满足精度要求。由迭代收敛时的阻尼比确定阻尼系数,该阻尼系数就是结构满足性能目标要求需要的阻尼系数。该方法考虑多阶模态的影响,不仅可以用于对称结构,还可以用于不对称的多高层建筑结构。(4)阻尼器的优化布置。以单层不对称结构作为平面不对称多高层建筑结构的简化模型,研究速度型阻尼器在平面的最优偏心位置。用随机振动理论将目标函数表示成关于阻尼器偏心的函数,继而用MATLAB优化工具箱求得目标函数取最小值时的阻尼器最优偏心位置。对阻尼器最优偏心位置进行参数分析,得出结论:影响阻尼器最优偏心的因素比较多,工程实践中难以精确求解最优偏心位置。因此,论文分析目标函数对阻尼器偏心的敏感性,并给出平面不对称结构中阻尼器的近似最优偏心取值的建议。用顺序搜索法优化阻尼系数在结构各层之间的分布,每层阻尼系数的平面分布满足阻尼器近似最优偏心的要求。对比该方法和遗传算法的优化计算结果,结果表明,该方法可以有效地在偏心结构中优化布置阻尼器。(5)将本文的理论分析方法应用于工程实例。更多还原

【Abstract】 In this paper, a series of research is carried out on vibration control of plan-asymmetric high-rise buildings with passive energy dissipation dampers, which mainly includes seismic response analysis of tall buildings with dampers, performance-based design method for structures with dampers, and optimal distribution of dampers in asymmetric structures. The specific contents are as follows:(1) Parameter analysis of dampers. The influence of damper parameters on vibration of SDOF system is analyzed. Base on parameter analysis, comparison is made between viscous and viscoelastic dampers’ influence on modal parameters of asymmetric one-storey structure and vibration reduction effect.(2) Improved Ritz method to analyze seismic response of tall building with non-classical damping. Improved Ritz Method adopts not only load dependent Ritz vectors but also frequency dependent Ritz vectors. Both vectors are generated by Lanczos Algorithm in which the frequency dependent Ritz vectors can be obtained after eigenvalue shift with square of the predominant excitation frequency. A linear transformation is made to the dynamic equation by using the Ritz vectors and then the pseudo-force method is employed to solve the coupled equation after transformation.(3) Performance-based design method for structures with energy dissipation devices. This paper advances two performance-based design methods:①Direct displacement-based seismic design method with performance target expressed by storey drift. MDOF structure is transferred to SDOF system. And the required total damping ratio of SDOF system to satisfy displacement demand for given earthquake wave is evaluated through displacement spectrum, which can be taken as the approximation of MDOF structure’s damping ratio demanded to meet performance requirement. Then the supplemental equivalent damping ratio and the corresponding damping coefficients of dampers are determined. Direct displacement-based design method can only be applied to symmetric structures②Multimode-based design method for buildings with dissipation devices. The performance index of structures is expressed by multi-mode. By introducing maximum displacement ratio of modes’ equivalent SDOF systems, the structure performance index can be represented as a function of maximum displacement of the first mode SDOF system. Then, the allowed maximum displacement of the first mode SDOF system can be calculated from the given performance target. The damping ratio demanded by the first mode can be identified from the displacement spectrum, and the supplemental damping ratio and the damping coefficients are determined. After that, the equivalent damping ratios supplied by the damping coefficients for other modes are calculated, and then the maximum displacement ratio and the correlation coefficients between modes are revised accordingly. Iteration calculation continues until the first mode damping ratio meets the precision requirement. The damping coefficients for the structure can be calculated from the convergent damping ratio. Multimode-based method can be applied not only to asymmetric structures but also to symmetric structures.(4) Optimal distribution of dampers. A single-storey asymmetric structure is employed as the simplified model of plan-asymmetric multi-storey structures to study the optimal plan distribution of viscous and viscoelastic dampers. Based on the random vibration theory, the objective function is expressed as a function of damper eccentricity. The optimum damper eccentricity is found by minimizing the target function with the optimization toolbox of MATLAB. Then, parametric analysis is carried out on the optimum damper eccentricity. It is concluded that there are too many factors influencing the optimal eccentricity of damper to calculate it precisely in practice. So the sensitivity of objective function to damper eccentricity is analyzed and the approximate optimal damper eccentricity is proposed. The Sequential Search Algorithm is employed to optimize the distribution of damper coefficients between different storeys, and the plan distribution of damper coefficients in every storey is in accordance with the approximately optimal eccentricity. The distribution of viscous dampers is optimized by the proposed method and GA algorithm respectively, and comparison of the seismic response reduction effect shows that the proposed method can get favorable result in relatively shorter time and is an effective method for the optimal distribution of dampers. (5) At last the theoretical methods are applied to an actual project.更多还原