| During the service period of bridge for decades or even hundreds of years,owing to the coupling effects of various unfavorable factors such as vehicle load,extreme load,long-term load,environmental corrosion,material aging and mutagenic effect,bridge structure generates damage accumulation and resistance attenuation inevitably,which even causes catastrophic accidents in extreme cases.Bridge influence line(BIL)presents a favorable application prospect in the field of structural damage identification,but so far,there are still many key problems to be solved for using IL as an effective tool to quantify the damage degree of bridge.This paper focuses on the topic of damage quantification method based on influence line change of beam structures and its verification,and carries out a detailed and in-depth study.The main research contents include the following three parts:(1)damage quantification of simply supported beam bridges based on deflection influence line(DIL)change;(2)damage quantification of continuous beam bridges based on DIL change;(3)damage identification based on the fusion of multi-sensor information.In the second chapter,a damage quantification method based on the IL change of a simply supported beam before and after damage is proposed.The damage quantification analysis is realized by identifying the change of flexibility and the relative change of stiffness.Through the numerical simulation of simply supported beams,the accuracy,the robustness against noise interference and the feasibility of multi damage identification are verified.Finally,a simple supported aluminum beam in the laboratory is further used to verify the method.In the third chapter,a damage quantification method based on the IL change of continuous beams before and after damage is proposed.As the IL change of continuous beam before and after damage is corrected,the IL change caused by the reduction of section stiffness is obtained.The quantitative analysis of damage is realized by the damage quantification method described in the previous chapter.The accuracy and robustness of the method are verified by several numerical examples of two span continuous beams.In the fourth chapter,based on the relative change of stiffness,a new damage evaluation index is constructed after multi-sensor information fusion.The relative change of stiffness index is combined with data fusion method,and the distance weight parameter is introduced to accurately locate the damage after making full use of the information of each sensor.Through several numerical examples,the damage sensitivity of simply supported beam and continuous beam at different measuring points is analyzed,and the influence of noise interference on the sensitivity is considered.Finally,the feasibility of optimizing damage identification with Dempster-Shafer(D-S)evidence theory is verified. |
