基于最敏感斜拉索张力指标的斜拉桥主梁损伤识别方法  

Damage Identification Method for the Main Girder of Cable-Stayed Bridge Based on the Tension Indices of the Most Sensitive Stay Cable

作　　者：李延强[1] 赵世英[1] 杜彦良 

机构地区：[1]石家庄铁道大学工程力学系,河北石家庄050043

出　　处：《中国铁道科学》2014年第2期20-25,共6页China Railway Science

基　　金：国家自然科学基金资助项目(50778116);河北省自然科学基金资助项目(E2012210061);河北省教育厅重点项目(ZH2012068);河北省科学技术研究与发展计划项目(11215611D);河北省人力资源和社会保障厅项目(436018)

摘　　要：斜拉桥结构主梁的损伤会引起恒载内力重分布,进而引起斜拉索张力变化。根据这一规律,结合BP神经网络算法,研究并提出基于最敏感斜拉索张力指标的斜拉桥主梁损伤识别方法。通过分析斜拉索张力对主梁损伤的敏感性,确定对主梁损伤最敏感的斜拉索,并将该斜拉索在主梁损伤前后的张力变化率定义为最敏感斜拉索张力指标;将主梁发生不同位置、不同程度损伤时对应的各最敏感斜拉索张力指标作为BP神经网络的输入并训练网络,根据训练误差自动确定网络的隐含层结构,由训练好的BP神经网络的输出确定主梁的损伤位置及损伤程度。以实验室独塔斜拉桥试验模型为例,采用有限元软件ANSYS建立其空间板壳有限元模型,运用给出的主梁损伤识别方法对该斜拉桥试验模型的主梁损伤进行识别,结果表明:该方法仅用1组4根斜拉索便可以较好的识别率实现对斜拉桥主梁不同位置、不同程度单点损伤的识别。Dead-load internal force will be redistributed and stay cables＇ tension will be changed when the main girder of cable-stayed bridge is damaged.According to this law and combining with BP neural network algorithm,a new damage identification method based on the tension indices of the most sensitive cable is studied and put forward to detect the damage in the main girder of cable-stayed bridge.The most sensitive stay cables for main girder＇s damage of cable-stayed bridge are obtained according to the analysis on the sensitivity of stay cable tension to main girder＇s damage,and the variation rate of the stay cable＇s tension before and after main girder＇s damage is defined as the tension index of the most sensitive stay cable.The corresponding tension indices of the most sensitive stay cables,obtained when the damage occurs to the main girder at different positions and degrees are regarded as the inputs of BP neural network,and the network is trained.The hidden layer structure of the network is determined automatically according to training error.Both the location and degree of damage for main girder are indicated by the outputs of the trained BP neural network.Taking the test model of a single-tower cable-stayed bridge for example,a space plate shell finite element model is established by ANSYS.The main girder＇s damage of the test model is detected by using the given method.It is shown that a good identification result for the main girder＇s single damage at different positions and degrees can be obtained by using only one group （four stay cables）cable tension indices.

关 键 词：斜拉桥 主梁 损伤识别 斜拉索 张力指标 神经网络 敏感性分析 

分 类 号：U448.27[建筑科学—桥梁与隧道工程]