Damage Detection Of Bridge Based On Difference Of Deflection Influence Line And Moving Principal Component Analysis

The bridge structures are always subjected to various adverse factors during its long-time service, such as material aging, extreme environmental, load effect, etc. which can cause the bridges injury. It will seriously threaten the safety of structures, cause a high number of casualties and huge property losses, if we could not diagnose and eliminate the damages timely.Based on the previous methods of damage detection, this paper put forward that difference of deflection influence line and moving principal component analysis. The former signature is able to overcome the defect which the traditional identification methods need a large number of sensors, the test is simple; The latter is based on modern computer technology to achieve monitoring online and evaluation about structural health condition. The main works include:Firstly, the significance of bridge damage identification and the research status in this field are introduced. The article discusses briefly the principles and the disadvantages about several relatively mature methods. Due to the deficiencies of current research methods, the difference of deflection influence line and moving principal component analysis are proposed.This paper derived analytic formula about the deflection influence line for simply support beam and arched bridge by using principle of virtual work. A brief explain in theory is given about two methods: the difference of deflection influence line and the curvature of deflection influence line. Based on the principal component analysis, the moving principal component analysis is put forward by selecting appropriate moving window and interval, and several major parameters are expounded.The deflection of arched beam under moving load is measured using BEAM3 element in ANSYS, which proved the feasibility of the deflection influence line to identify structural damage. For the method of moving principal component analysis, respectively to simulate the dynamic response about simply supported beam and Hai Zhu bridge model under different conditions, the results indicate that these methods can successfully identify the damage of simple supported beam, as well as a complex steel structure.Experiments are tried on simply supported beam and Hai Zhu bridge model, respectively.The influencing rule of the methods proposed this paper changing with moving speed, crack depths and damage locations are analyzed. The laboratory model tests are made to verify the theoretical calculation. The results show those methods have a good recognition effect, which not only identify the damage, but also identify damage localization successfully.