基于联合智能算法的大跨度斜拉桥体系可靠度评估  

System reliability assessment of cable-stayed bridges based on a combined intelligent algorithm

作　　者：鲁乃唯[1,2] 刘扬[2] 肖新辉[2] 殷新锋[2] 

机构地区：[1]东南大学土木工程学院,南京210096 [2]长沙理工大学土木与建筑学院,长沙410114

出　　处：《应用力学学报》2015年第5期858-864,902,共7页Chinese Journal of Applied Mechanics

基　　金：国家重点基础研究发展计划(973计划)(2015CB057705);国家自然科学基金(51378081);江苏省博士后科研资助项目(15010458)

摘　　要：在随机荷载作用下,大跨度斜拉桥结构体系具有显著的失效历程,使得运营期的体系可靠度评估尤为重要。根据大跨度斜拉桥结构体系失效特点建立了数学模型,提出了基于径向基函数神经网络和β约界法的联合智能算法。以具有4对斜拉索的法国Brotonne斜拉桥为算例,验证了该方法对于斜拉桥结构体系可靠度分析的可行性。最后,将该智能算法应用于主跨为420m的双塔混凝土斜拉桥在承载能力极限状态下的体系可靠度评估,并进行了参数分析。研究结果表明:联合智能算法在具有显著失效历程特征的斜拉桥结构体系可靠度评估中具有较好的适用性;Brotonne斜拉桥简化结构的体系可靠指标上限和下限分别为3.1571和3.1103,刚构体系混凝土斜拉桥的主要失效路径为边跨斜拉索强度失效导致塔梁交界处索塔弯曲失效;斜拉索抗力退化是影响斜拉桥结构体系可靠度的重要因素,与斜拉索疲劳损伤相比,斜拉索锈蚀导致斜拉桥在运营期的体系可靠度下降趋势更大。斜拉索的养护和及时更换对保证在运营期斜拉桥的体系可靠度水平具有重要的意义。Long-span cable-stayed bridges exhibit remarkable failure sequences under random loads, which make it important for system reliability assessment of these bridges. The corresponding mathematical models are established based on the failure properties of the long-span cable-stayed bridge. A combined intelligent algorithm associated with RBF(radial basis function) neural networks and β-bound method is proposed. A numerical example associated with Brotonne Cable-stayed Bridge, which had four couples of cables, is presented to demonstrate the feasibility of the proposed method for structural system reliability assessment. At the end, as an engineering example, a two-tower concrete cable-stayed bridge with a mid-span of 420 m is adopted to demonstrate the application of the proposed method. System reliability of the bridge under ultimate limit state is analyzed. Numerical results show that, the intelligent algorithm is applicable to system reliability assessment of cable-stayed bridges, which exhibit significant failure sequences. The upper bound and lower bound of system reliability index of Brotonne cable-stayed bridge are 3.1571 and 3.1103, respectively. The main failure sequence of the cable-stayed bridges is strength failure of cables in side-span followed by bending failure of towers in the cross section of tower and girder. Degradation of cables is the main factor to influence on system reliability of cable-stayed bridges. Compared with fatigue damage of cables, the corrosion of cables leads to a larger decline of system reliability indices. It is important for managers to provide maintenance and prompt replacement measures in order to ensure the system reliability of cable-stayed bridges in operational period.

关 键 词：桥梁工程 斜拉桥 联合智能算法 体系可靠度 失效路径 抗力退化 

分 类 号：U448.27[建筑科学—桥梁与隧道工程]