Research On Bridge Damage Identification Method Considering Vehicle Load Movement Effect

Vehicle dynamic weighing technology has the characteristics of fast,continuous and accurate measurement.It can be used to check vehicle overload and illegal operation,and has been widely used at home and abroad.It has been found that the information collected by the vehicle dynamic weighing system can also be used to monitor the safety of bridge structures and provide a new method for bridge damage identification.Some scholars have proposed a damage identification method based on virtual axes using the dynamic weighing system arranged on the bridge structure,which can be used for short-span simply supported bridges and statically indeterminate bridges.In the bridge weighing motion calculation,a weightless axle called "virtual axle" is introduced,and the virtual axle weight is calculated by the displacement influence line.This method can be used to quickly identify damage to bridge structures,but its limitation is that it can only be applied to one-dimensional structures,that is,there is only one fixed position lane.If most bridges are considered to be multi-lane,the virtual axle method The error in the recognition of damage is large,and it is easy to cause misjudgment.Therefore,in order to make the virtual axle method effectively applied in the actual bridge engineering,this paper improves the existing virtual axle method and corrects the displacement influence line.The research proves that the improved virtual axle method is suitable for multi-lane actual bridge pavement.Increased practical engineering value.The difficulty of the improved virtual axle method is how to extend the one-dimensional space structure to the space structure of the two-dimensional bridge.In order to solve the problem of lateral distribution of loads on multiple lanes of bridges,a lateral load distribution coefficient is introduced,which can improve the recognition accuracy of the virtual axle weight.The numerical simulation example is used to compare the methods that do not consider the lateral distribution and consider the lateral distribution of the load.The results show that the improved virtual axle method has high accuracy for the recognition of the virtual axle when the vehicle is driving at any position on the bridgesurface.Improve the effectiveness of the virtual axle algorithm.Through the Monte Carlo simulation,the single vehicle distribution of the horizontal single-lane distribution of the bridge and the load of the complex vehicle distribution with multi-vehicle and multi-lane distribution are introduced to identify and analyze the damage and location of the bridge.The results show that the improved virtual axle method can detect local small damage of the bridge structure.The influence of key parameters,such as the position of the bridge to the sensor,the arrangement position of the cross bridge,and the noise level,are studied.The results show that the different distribution modes of the sensor have different effects on the damage identification accuracy,but the noise level has no effect on the recognition effect.Finally,the improved virtual axle method is applied to the actual engineering Jinji bridge structure to verify,and the identified damage area is compared with the actual damage position,which further proves the effectiveness of the improved virtual axle method.