基于首超破坏机制的大跨斜拉桥抖振动力可靠性分析

Dynamic Reliability of Buffeting Responses in Long-span Cabled-Stayed Bridges by the First Excursion Mechanism

分别采用泊松分布和马尔可夫过程 ,给出了在一次强风作用下以及在设计基准期内桥梁结构某一特定截面或节点的抖振动力可靠性分析方法。然后 ,考虑斜拉桥的结构特点及其承受风荷载的具体情况 ,确定了以斜拉桥的主梁系统为研究对象的结构体系抖振动力可靠性分析模型。在此基础上 ,采用串联失效模式 ,建立了斜拉桥主梁系统抖振动力可靠性分析过程。本文采用有限元法分析结构的空气静力响应。为了快速、准确地计算结构的抖振响应 ,考虑气弹力与抖振力的联合作用以及多模态耦合效应 ,采用有限元法和虚拟激励法相结合分析结构的抖振响应。最后 ,以某大跨斜拉桥为工程背景 。

In this paper the dynamic reliability of buffeting responses (DRBS) for the structural system of long-span cable-stayed bridges is studied based on the first excursion mechanism. Firstly, based on the assumptions of Poisson and Markov processes respectively, the analytical approaches of the DRBS are studied for a specific cross-section or point of the bridge structure subjected to a strong wind attack or during the whole structural design reference period. Then, according to the characteristics of the structural system and wind loads of cable-stayed bridges, their deck systems are taken as the basic analysis models in the research of DRBS. Based on the serial destructive mode, the computational process of the DRBS for the deck system of long-span cable-stayed bridges is established. The aerostatic responses of long-span cable-stayed bridges are computed by means of the finite element method (FEM). In order to compute the dynamic responses of the structure accurately and more efficiently, the finite element method (FEM) combined with the pseudo-excitation method (PEM) is used to analyze the buffeting responses. The self-exited forces associated with the buffeting forces as well as the multi-mode influence are also taken into account in the above buffeting analysis. Finally, with a long-span cable-stayed bridge as a case study, the dynamic reliability due to the buffeting responses of the bridge deck is evaluated.