Assessing Probabilistic Extreme and Fatigue Responses of Wind-Excited Structures through Integration of Both Uncertainty and Directionality with a System Perspective

更好地模拟和量化风荷载对建筑物和结构的影响对于结构设计和减轻风灾是至关重要的。风洞研究和结构动力响应分析提供了风致极端响应和疲劳响应随风速和风向变化的信息。然后通过进一步考虑风速和风向的变化来评估结构的整体抗大风性能。由于在给定风速下引起最大风荷载和结构响应的最不利风向并不一定与最强风向一致，因此考虑方向性的影响比用忽略风方向性的“最坏情况”方法分析可以得到更经济的结构设计。研究发现，目前对方向性效应的预测与现有方法存在很大差异。此外，这些方法不能在统一的框架内考虑不确定性和方向性。由于缺乏对这些方法的准确性和有效性的审查，以及缺乏针对不确定性和方向性的统一方法，从风洞研究中获得的详细和全面的风荷载信息不一定会导致风振结构设计的预期改进。本研究将以系统的观点在统一的框架内考虑风、空气动力学和结构特性的不确定性和方向性。将制定简化的程序，以便在未来的设计规范和标准中使用。这些新的工具和知识还可以用于基于性能的设计和结构系统抗多种危险的评估。本研究的目的是探索透明和可靠的方法，以更好地评估概率多极限状态响应，以支持风振结构的可靠性和基于性能的设计。这项研究的目标如下：1)非高斯响应过程的概率极值和疲劳响应的建模；2)定向极值风速的建模；3)同时考虑不确定性和方向性的概率极值和疲劳响应的预测；4)考虑多个极限状态响应的不确定性和方向性的影响，评估结构的性能。研究结果将有助于就如何最好地量化风向影响达成共识，从而可以减少或消除现有方法的巨大差异。该框架还将帮助风工程实验室更好地将风洞研究结果与风模型相结合，以便针对风荷载进行结构的成本效益设计。

Better modeling and quantification of wind load effects on buildings and structures are essential for structural design and wind hazard mitigation. Wind tunnel studies and structural dynamic response analysis provide information of wind-induced extreme and fatigue responses as functions of wind speed and direction. The overall structural performance to strong wind is then evaluated by a further consideration of variations of wind speed and direction. As the most unfavorable wind direction that causes the largest wind load and structural response under given wind speed does not necessarily align with the direction of strongest wind, consideration of directionality effects can result in more economical design of structures as compared to the analysis with the "worst case" approach of disregarding wind directionality. The discrepancies of predictions from current existing approaches on directionality effect are found to be significant. Furthermore, these approaches cannot account for uncertainty and directionality in a unified framework. Due to a lack of scrutiny on the accuracy and effectiveness of these approaches, and a lack of a unified approach for both uncertainty and directionality, the detailed and comprehensive wind loading information derived from wind tunnel studies may not necessarily lead to expected improvement in the design of wind-excited structures. This research will consider the uncertainty and directionality of wind, aerodynamics, and structural characteristics in a unified framework with a system perspective. Simplified procedures will be developed for possible use in future design codes and standards. The new tools and knowledge can also be used for performance-based design and assessment of structural systems against multiple hazards.The goal of this research is to investigate transparent and reliable approaches for better assessing probabilistic multiple limit state responses to support a reliability and performance-based design of wind-excited structures. This research has the following objectives: 1) modeling of probabilistic extreme and fatigue responses of non-Gaussian response processes, 2) modeling of directional extreme wind speeds, 3) prediction of probabilistic extreme and fatigue responses considering both uncertainty and directionality, and 4) assessing structural performance with the effects of uncertainty and directionality accounting for multiple limit-state responses. The research findings will help develop consensus on how wind directionality effects are best quantified, thus the large discrepancies of existing approaches can be reduced or eliminated. The framework will also help wind engineering laboratories to better integrate wind tunnel study results with wind modeling for cost-effective design of structures to wind loads.