Research On Stress State Inversion Method Of Concrete Bridge Based On 3D Scanning

Three-dimensional laser scanning technology is a technology that can accurately and efficiently collect the apparent information of objects.It has been widely used in topographic surveying,digital protection of cultural relics,industrial surveying and other fields,and is gradually being used in the field of bridge engineering.Although the development of hardware facilities of 3D laser scanning technology is becoming more and more mature,there are still many problems to be solved for the post-processing of point cloud data and the application of integration with multidisciplinary.At present,the recognition of the spatial form of the existing bridge structure based on three-dimensional point cloud data has been realized,but the systematic and quantitative connection between the form change and the stress state of the bridge has not yet been established.This research combines the holographic point cloud and inversion theory of the bridge structure to optimize the relevant mechanical parameters of the structure through the method of displacement back analysis,and quantitatively evaluate the stress state of the existing bridge structure.The main research contents are as follows:(1)In order to test the feasibility of 3D laser scanning technology applied to bridge structure deformation monitoring and the reliability of data,the key data processing technology of 3D laser scanning technology applied to bridge structure deformation monitoring is studied,and then the relationship between point cloud point density and deformation monitoring accuracy is obtained through precision verification experiment.The results show that the accuracy of deformation monitoring using 3D laser scanning technology can reach sub millimeter level.(2)Based on the 3D point cloud model of bridge structure,the geometric dimension extraction and the apparent damage location method are studied,and the accurate geometric dimension data of the structure is obtained by extracting the feature point information from the slice point cloud.The method of structural damage identification is discussed.According to the characteristic that curvature can reflect the curve discontinuity,the method of identifying the structural damage by identifying curvature mutation is proposed,which is verified by the indoor simply supported beam experiment.(3)Based on the measured spatial dimension information and damage location of the bridge,a method for accurately constructing the numerical simulation analysis model of the bridge structure is proposed.The fusion application of field measured point cloud model,theoretical design geometric model and finite element model is realized,which solves the weakness of traditional finite element modeling ability and the shortcomings of model error,and makes the simulation model close to the actual situation to the greatest extent.(4)In order to establish the relationship between the structural deformation mode and its stress state,a multi Island genetic algorithm is proposed to optimize the mechanical parameters of the structure,inverse the actual mechanical parameters of the structure,and modify the initial model based on the inversion parameters.Based on the modified model,the deformation mode of the structure can be predicted and analyzed.