دانلود رایگان مقاله اندازه گیری لرزش مبتنی بر روش ساده برای تشخیص آسیب پل خرپایی

ABSTRACT

The bridges experience increasing traffic volume and weight, deteriorating of components and large number of stress cycles. Therefore, assessment of the current condition of steel railway bridges becomes necessary. Most of the commonly available approaches for structural health monitoring are based on visual inspection and non-destructive testing methods. The visual inspection is unreliable as those depend on uncertainty behind inspectors and their experience. Also, the non-destructive testing methods are found to be expensive. Therefore, recent researches have noticed that dynamic modal parameters or vibration measurement-based structural health monitoring methods are economical and may also provide more realistic predictions to damage state of civil infrastructure. Therefore this paper proposes a simple technique to locate the damage region of railway truss bridges based on measured modal parameters. The technique is discussed with a case study. Initially paper describes the details of considered railway bridge. Then observations of visual inspection, material testing and in situ load testing are discussed under separate sections. Development of validated finite element model of the considered bridge is comprehensively discussed. Hence, variations of modal parameters versus position of the damage are plotted. These plots are considered as the main reference for locating the damage of the railway bridge in future periodical inspection by comparing the measured corresponding modal parameters. Finally the procedure of periodical vibration measurement and damage locating technique are clearly illustrated.

9. Conclusions

A simple technique was proposed to locate the damage region of railway bridges based on measured model parameters. The case study shows the applicability of the introduced technique. The technique mainly depends on plots of variation of model parameter with respect to the position of damage which was obtained by validated FE model. The validated FE model, which represents more reasonably the actual static and dynamic behavior of the railway bridge at the time of validation, was obtained by comparing the measured responses with FE model given responses. The periodical modal parameter measurement has to be conducted and obtained measurement should be compared with above plots to locate the region of damage. As this periodical modal parameter measurement is based only on acceleration under usual moving train loads, it can be concluded that this measurement can be cheaply acquired and the proposed method provides an inexpensive damage locating technique. Influence of partially loss of member cross section for change of model parameters are recommended for future studies.