Study On Working State Evaluation Method And Modal Characteristics Of Existing Railway Bridge Piers

Railway bridges are often exposed to dynamic train load, wind load, etc. and also to initial disease, aging of construction material, artificial damages, environmental disasters and other factors, which led to the accumulation of structural damage, the attenuation of resistance, thus having influences on the use of bridge structures and the safety for railway transportation. Therefore, it is necessary to carry out all-round health test on bridge structures, especially on piers. Moreover, it is of great importance to study the working state evaluation method on bridge piers and to develop simple, rapid and accurate testing method.In this paper, the working state evaluation method and the related testing technique are studied. The main research work and results include:The working state evaluation method is systematically studied based on the natural frequency of piers and the codes'regulation, and several traditional natural frequency testing methods of piers are analyzed. As an important part, the theory and the use of the impact vibration test method are studied and made detailed discussion of, which is simple in theory and easy to conduct.A number of tests on existing bridge piers based on the impact vibration test method are introduced. Taking a bridge with pile foundation as an example, the first natural frequency of piers is identified, the impact of the parameter over pier natural frequency is studied and the natural frequency formula by analyzing the data collected is obtained.The finite element models for the piers are built according to the design blueprint to calculate the natural frequencies of them, and a comparison with the test results is made. By using the finite element program, the regular patterns of the influences that each parameter has on the natural frequencies of the piers are analyzed, and some valuable results are obtained.The summation is made on the potential improvements, and opinions are proposed on the future developments of the working state evaluation method.