隔震结构反应谱复振型叠加法关键问题研究

Now the conventional response spectrum real mode superposition method, which is based on the assumptions of classical and small damping, is always adopt in the design of isolated buildings. However, the effect of non-classical damping is ignored in this method such that the isolated structure responses cannot be predicted accurately, and when the damping of the isolation layer is larger, the method cannot keep the design of isolated buildings safe. Dynamic analysis methods associated with complex modes can address the non-classical damping problem. Based on theoretical method, numerical simulation and experiment approach, this study is aim at developing a response spectrum complex mode superposition method (RSCMSM) applied for isolated buildings. Firstly, a mode contribution evaluation indicator, a mode cut-off criteria, contributions of truncated high-frequency modes, velocity response spectra and high-damping scaling factors, which are closely related to the RSCMSM, are studied using theoretical method and numerical simulation. Then, through numerical simulation and experiment approach, the effect of seismic non-stationary on isolated structure responses is investigated. Finally, utilizing a proper seismic evolutionary spectrum model, a RSCMSM used for the design of isolated buildings is developed to consider the effects of amplitude and frequency non-stationary characteristics of ground motions through random vibration theory. This research is to improve the complex mode theory and response spectrum method for non-classical damping systems and provide theoretical direction and technical support for the design of isolated buildings.

目前，隔震结构设计主要采用经典、小阻尼假定下的传统反应谱实振型叠加法，它忽略了非经典阻尼的影响，无法准确预测隔震结构地震反应，在大阻尼情况下会导致结构设计偏于不安全。基于复振型的动力分析方法可以有效地解决非经典阻尼问题。本项目拟通过理论研究、数值分析和试验手段，紧密结合隔震结构长周期、大阻尼的特点，建立针对隔震结构设计的反应谱复振型叠加方法。首先，通过理论研究和数值分析，研究与复振型反应谱方法相关的振型贡献评估指标、振型截断准则、高阶振型贡献、速度反应谱和大阻尼修正系数；然后，将数值分析与试验手段相结合，研究地震动时、频非平稳特性对隔震结构反应的影响规律；最后，基于随机振动理论，采用合适的地震动演变谱模型，建立考虑地震动时、频非平稳特性的复振型反应谱隔震设计方法。本项目旨在发展与非经典阻尼系统有关的复模态理论和反应谱方法，为隔震结构设计提供可靠的理论指导和技术支持。

随着减震(振)控制技术的发展、应用，愈来愈多的实际结构表现出非经典的大阻尼特性，基于经典的小阻尼假定建立起来的传统反应谱振型叠加方法，已不能适应抗震设计发展的需求。本项目针对隔震结构，结合其长周期、大阻尼和局部非线性特性，建立了一套复模态分析理论和设计方法。首先，提出了复振型质量参与系数的概念，用来评估各个振型的贡献程度，确定合理的振型参与数目；其次，建立了复振型截断修正的静力和加速度方法，考虑高阶振型对结构响应的影响；同时，研究了非经典阻尼系统临界阻尼和过阻尼特性，建立了广义的复振型叠加方法，并将其推广到了连续系统，完善了复模态理论；最后，针对隔震结构的局部非线性问题，提出了基于复振型反应谱的等效线性化设计方法。本项目部分成果已被《建筑隔震设计标准》(GBT 51408-2021)采纳，相关隔震设计软件也已大量推广，这些展示了本项目的理论指导意义和工程应用前景。