Design, Verification, and Test of the Bridge Structure Vibration Similarity Model

Abstract

At present, the method of model testing is rarely used to study the low-frequency vibration problems of bridge structures, because it is difficult to keep the similarity between the bridge model and the prototype in model testing. Based on the similarity law of elastic force, a similarity model of a 32-m simply supported box girder bridge, a model bridge with a geometric similarity ratio of 10∶1, was designed and manufactured in this paper. The validity of the similarity model was verified by modal testing and numerical simulation. Then, through the hammer test of the similarity model, the vibration transmission characteristics of the model box girder between the panels and along the longitudinal direction of the bridge were studied. Also, the influence of the bridge support on the box girder vibration and the vibration reduction effect of the bridge support were analyzed. The results showed that when the top plate of the box girder is excited, the vibration attenuation from the top plate to the bottom plate is the fastest, followed by the top plate to the web, and from the top plate to the wing plate is the slowest. In the frequency range of less than 45 Hz, the vibration of the top plate attenuates slowly along the longitudinal direction of the bridge; in the frequency range of 45–200 Hz, the vibration of the top plate attenuates rapidly from the middle span to the 1/4 span section of the bridge and attenuates slowly from the 1/4 span to the support section of the bridge. The vibration reduction effect of the elastic support on the bridge pier was related to support stiffness and vibration frequency; the general rule was that the smaller the support stiffness, the better the vibration reduction effect. In addition, the vibration reduction effect varied greatly with different vibration frequencies.