Research On Damage Identification Of Beam Bridge Based On Generalized Curvature Modal Information Entropy And Generalized Angle Difference Curvature Information Entropy

As the hinge of transportation,the safety of bridge is related to the healthy development of the national economy and the safety of people’s lives and property.Due to the adverse environmental factors and the influence of human actions,the bridge in service is damaged to different degrees,resulting in the deterioration of bridge structural performance,which seriously threatens the normal operation of traffic and personal safety.Bridge structural damage identification plays an important role of bridge health monitoring,which has been widely concerned by scholars at home and abroad.Based on D-S evidence theory,wavelet analysis,BP neural network and other methods,related research on bridge damage identification has been carried out.However,there are still some problems,such as large noise interference,insufficient data mining,and the sensitivity of damage to be improved.In this paper,based on the theory of curvature mode,structural angle and information entropy,the generalized curvature modal information entropy(GCMIE)index and generalized angle difference curvature information entropy(GADCIE)index are proposed to identify damage.In order to verify the effectiveness of damage identification,the practical application of the index was analyzed by the numerical simulation of simple supported beams with different cross-sections and the test of simple supported steel beams;finally,it is applied to the damage identification of continuous beams,and the practicability is compared.The main work is as follows:(1)Summarize domestic and foreign bridge damage identification methods,which provides the foundation and direction for the research of this paper;In addition,the application of angle sensor and information entropy in bridge deformation and damage identification is introduced,which provides a new method for bridge damage identification ideas.(2)In order to identify the damage of simply supported beams,GCMIE index of damage identification was proposed by using the curvature modal difference before and after the damage,combined with the advantage of information entropy to deeply mine the data.The ability of damage identification of simple supported beams with different cross-section is discussed,and the anti-noise performance is analyzed by introducing White Gaussian Noise.The research shows that the GCMIE index can accurately identify the damage of the simply supported rectangular beam and the simply supported box girder bridge at different positions and degrees,and it has certain anti-noise ability.(3)In order to further verify the effectiveness of GCMIE index in practical application,the vibration test is carried out by simulating the damage of the opening of the simply supported steel beam,and the natural frequency is analyzed by using the numerical model established by ANSYS and MIDAS/civil finite element software.The results show that the accuracy of the test results of the simply supported steel beam meets the practical needs,and the GCMIE index can accurately locate the different damage positions,which has good engineering value.(4)Aiming at the problem of less research on the angle of bridge structure,the relationship between moving load position and angle difference is derived using the principle of virtual work,and gotten the curvature of the angle difference in the damaged area is not zero.In order to solve the problem that the non-zero value of the angle difference curvature in the damaged position is not prominent and the angle difference curvature in the non-destructive region is not zero,GADCIE index is proposed based on the information entropy theory,meanwhile,the quantitative damage degree calculation method is given.Using ANSYS software,numerical model of simply supported beams with different cross-sections were established to verify the effectiveness of index identification damage,and noise was introduced to analyze its anti-noise performance.The results show that the GADCIE index is less affected by the non-destructive elements,and it can accurately identify the damage location of the simply supported beam,and it has a certain ability to resist noise.(5)Based on the GCMIE and GADCIE indexes proposed in this paper,the continuous beam damage identification is studied,and the identification results under the two indexes are compared and analyzed.The results show that: under the influence of the support and the non-destructive elements,the identification effect of the GCMIE indicator is not good,but the GADCIE indicator can efficiently and accurately identify all damages and have a certain ability to resist noise.