Experimental study of a hand-drawn cart for measuring the bridge frequencies

This paper presents an experimental study of a hand-drawn cart designed for measuring the bridge frequencies. The technique presented herein is considered as an indirect approach for bridge frequency measurement, in that the vibration sensor is mounted indirectly on the moving cart, rather than on the bridge, as is the case with the conventional direct approach. The idea of developing a hand-drawn test cart is that it allows us to measure the bridge frequencies in a human-controlled, efficient, and mobile way. The dynamic characteristics of a test cart are crucial to the successful identification of the frequencies of the bridge using the test cart. In this study, focus is placed mainly on two issues: the elastic properties of the cart wheels and the reliability of bridge frequencies extracted from the test cart. Various tests are conducted under various operating conditions, including the ambient vibration test, free vibration test, ground dynamic test, and field test. It is demonstrated that the hand-drawn cart presented herein can be reliably used in the field for measuring the bridge frequencies. Furthermore, some qualitative guidelines that are crucial to the development of feasible test vehicles are drawn from the test studies presented herein.