考虑实测交通流的数字孪生系统在斜拉桥结构状态评估中的应用

Application of Digital Twin System Considering Measured Traffic Flow in Structural State Evaluation of Cable-stayed Bridge

为评估运营期间桥梁结构健康状态,构建了以实测交通流荷载为连接的桥梁数字孪生系统。依靠ETC门架车辆荷载监测系统及索力监测系统的海量监测数据,提出了一种包含物理数据的采集与前处理、虚拟模型的构建与蒙特卡洛模拟、模型间的交互及结构状态评估的数字孪生技术框架。该方法依仗ETC门架车辆监控数据提取桥梁车辆荷载分布特征,利用蒙特卡洛方法丰富运营期间车辆荷载负样本,应用有限元模型定义结构极限状态。分别以塔底截面弯矩、主梁跨中挠度作为承载能力极限状态和正常使用极限状态的目标向量,通过具有车辆荷载特征的群索索力搭建了物理空间与虚拟空间的联系。最后基于相异测度建立了斜拉桥结构状态评估的评价指标和阈值体系,并依托国内某混凝土独塔斜拉桥工程项目对该评判方法进行了论述。结果表明:经实测车流特征修正后的相异测度具有更强的分类能力,且更贴近结构的实际响应行为;以相异测度构建的评价指标和阈值体系的评估结果符合桥梁结构服役期间状态变化特征,可应用于运营期间的结构状态评估工作;数字孪生技术融合了有限元模型中整体结构内各构件的响应协调关系和监测数据中结构的真实变化规律,能够胜任桥梁结构全生命周期的健康状态评估工作。

In order to assess the health status of bridge structure during operation,a bridge digital twin system connected by measured traffic flow loads is constructed.Relying on the massive monitoring data of ETC gantry vehicle load monitoring system and cable force monitoring system,a digital twin technology framework including physical data acquisition and preprocessing,virtual model construction and Monte Carlo simulation,interaction between models and structural state assessment is proposed.With this method,the vehicle load distribution characteristics of the bridge are extracted relying on the ETC gantry vehicle monitoring data,the negative samples of vehicle loads during operation is enriched by using Monte Carlo method,the limit state of the structure is defined by applying the finite element model.Taking the bending moment of the pylon bottom section and the mid-span deflection of the main beam as the target vectors of the bearing capacity limit state and the normal service limit state respectively,the connection between physical space and virtual space is built through the group cable forces with vehicle load characteristics.Finally,the assessment indicator and threshold system for the structural state assessment of cable-stayed bridges is established based on dissimilarity measure,and this assessment method is described based on a domestic concrete single-pylon cable-stayed bridge project in China.The result shows that(1)the dissimilarity measure modified by the measured traffic characteristics has stronger classification ability and are closer to the actual response behavior of the structure;(2)the assessment result of the assessment indicator and threshold system constructed with dissimilarity measure are in line with the state change characteristics during the service of the bridge structure,and can be applied to the structural state assessment during operation;(3)The digital twin technology integrates the response coordination relationship of each component in the overall structure in the finite element model and the real change rule of the structure in the monitoring data,which can be competent for the health status assessment of the whole life cycle of the bridge structure.