The Bridge Damage Identification Based On The Change Of Natural Frequency

A lot of scholars began to research Natural frequency-based damage identificationtechniques a long time ago. But that research only in the field of mechanical and aerospace. Inrecent years, with the rapid development of the world economy, a large number of civilengineering structures had been constructed, just like the railway and the highway bridge andother large-scale civil engineering structure. A part of these bridge structures suddenlycollapse, due to their own damage accumulation, because of neglect to regular damageexamination. These accidents have aroused the domestic and the foreign scholar’s widespreadattention. How to Introduction the damage recognition technology based on the naturalfrequency change’s, which test simply and have the accurate result, to the large-scale civilengineering structure needs a lot of further research. This article launches the analysis to therelationship between the damage and natural frequency change in view of different simplysupported beam model which have different ratio of steel. This paper was mainly studied onthe following aspects.For bridges of simply supported forms which commonly used in today’s engineering. Weused the different ratio of steel to manufacture10concretes simple beam model. We carrieson the modal analysis before the beam damaged in order to obtains its initial natural frequency.Selects the graduation load mode to damage the beam that can simulation varying degreedamage. After achieving certain load rank, then unloading and carries on the modal analysiswith damaged structure. After obtaining the damage natural frequency, carries on thecontrastive analysis with the natural frequency that undamaged. We can find that the structurenatural frequency reduces along with the damage increases. We compared the experimentaldate which came from two different ratio of steel found that if we increase the ratio of steel,the natural frequency will have a certain degree of decline. Conclusion from the analysis wecan see that the structure natural frequency influenced mainly by their own stiffness and theextent of the damage. According to the data from the experiments, we use ANSYS finiteelement software and theory of the rule of the algorithm to get checked and proving thereliability and accuracy of the rules.Through the software analysis and experimental research proof, the natural frequencymainly related to their own stiffness. The greater the stiffness is, the natural frequency value ishigher. The structure which has certain stiffness, the natural frequency increases along withthe damage reduces. In other words, the greater the extent of damage increase, the faster thenatural frequency decrease. The first-order frequency’s change was not only most sensitivelyto damages, but also most effective to the damage recognition. In addition, in the damagerecognition examination, the external environment factors also have the quite important influence to the result accuracy.