强/台风过程大型跨海桥梁多重不确定性复合抖振动力可靠性分析

The wind-resistant safety problem of the large scale sea-crossing bridge has drawn great attention with the rapid development of the costal transport infrastructure system. The dynamic reliability problem of the buffeting response under hurricanes/typhoons is the frontier and hotspot in the bridge wind-resistant study. The current researches in this field are in quite limited number; several challenges fall on the understanding, analysis and quantification for the different types of uncertainties in this problem. This project focuses on the fundamental researches on the dynamic reliability of the buffeting response for the large scale sea-crossing bridge under hurricanes/typhoons. The probabilistic model analysis method of the non-stationary spatial-temporal random field and the effective hierarchical probabilistic model analysis method of the complex multi-modeling engineering problem are established by expanding the earlier achievement of the applicant to these two research fields. The controlling factors and their influences on the spatial-temporal non-stationarity of the wind field are studied; the hierarchical non-stationary spatial-temporal random wind field model considering external influencing factors and the hierarchical probabilistic model of non-stationary buffeting analysis are constructed. Then the methods for the dynamic reliability computation and sensitivity analysis considering coupling effects of random structural parameters and design uncertainties are established based on the proposed probabilistic analysis methods and models. Finally the dynamic reliability analysis approach of the buffeting response with multi-uncertainty coupling is generated. This project can improve the bridge wind-resistant theory and help promoting the dynamic reliability analysis of the buffeting response from theory to practice. The research outcomes are of significant meanings both theoretically and practically.

随着我国沿海交通基础设施的高速发展，大型跨海桥梁抗风安全问题突出，其中强/台风过程抖振动力可靠性问题是该领域的前沿和热点，现有研究十分有限，在对各类不确定性因素的认识、分析和量化这一核心问题方面尚存难题。项目拟就强/台风过程大型跨海桥梁抖振动力可靠性分析开展基础性研究。通过将申请人前期工程概率模型分析研究成果拓展至时空随机场和多模型复杂问题领域，提出非平稳时空随机过程的概率模型分析方法和复杂工程问题的实用层次概率模型分析方法，探明风场时空非平稳性的控制性因素及其影响规律，建立考虑外部参数影响的多层次非平稳时空随机风场模型和非平稳抖振分析层次概率模型。然后基于建立的概率分析方法和模型，提出考虑结构随机参数和分析不确定性复合的动力可靠度计算及敏感性分析方法，建立多重不确定性复合抖振动力可靠性分析流程。研究成果可完善桥梁抗风理论体系，推动抖振动力可靠性分析由理论走向实践，具有科学意义和实用价值。

大型跨海桥梁是沿海交通系统的重要节点和关键基础设施，面临来自海洋环境的各类型极端灾害作用，强/台风作用下的大型跨海桥梁安全问题是当前研究的热点和前沿。项目首先进行了跨海桥梁风荷载研究，根据进化谱理论通过引入调制函数模拟三维非平稳风速场，基于CFD数值风洞技术来获取桥梁构件的风特性参数，并在时域范围求解静风荷载、非平稳抖振力和非平稳自激力，构建了跨海桥梁非平稳随机风场及风荷载分析的方法流程。然后项目开展了桥梁风致稳定性安全评价研究，考虑系统问题中的多模型/多重不确定性复合提出了复杂问题的层次概率模型构建方法，基于提出的方法建立了广泛适用性的静风稳定性概率分析模型和颤振稳定性概率分析模型，并对案例桥梁进行了风致稳定系统可靠性分析。最后项目进行了抖振动力可靠性研究，基于风荷载分析结果采用精细化非线性时程分析获得桥梁非平稳抖振响应，考虑响应非平稳特征基于首次超越破坏准则求解不同平均风速下主梁非平稳抖振时变动力可靠度沿跨长的变化曲线，构建了跨海桥梁非平稳风致抖振可靠性分析的方法流程。上述研究有助于完善大型跨海桥梁结构抗风理论体系，为强/台风作用下大型跨海桥梁动力可靠性分析在工程设计实践中的应用奠定理论基础，具有理论意义和实用价值。