Vehicle Scanning Method for Bridges

8Hand‐Drawn Cart Used to Measure Bridge Frequencies

This chapter presents an experimental study of a hand‐drawn cart used for measuring bridge frequencies. The idea of developing a hand‐drawn test cart is that it allows us to measure the bridge frequencies in a handy and mobile way, while examining each of the parameters of the device in a close way. The dynamic characteristics of the test cart are crucial to the successful identification of the bridge frequencies of the bridge. This chapter primarily focuses on two issues: the elastic properties of the cart wheels/tires and the reliability of bridge frequencies extracted from the test cart. 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 bridge frequencies. Furthermore, some qualitative guidelines essential to the development of feasible test vehicles are drawn from the field test. The materials presented in this chapter are based primarily on Yang et al. (2013b).

8.1 Introduction

The frequencies of a bridge are among the most important information for health monitoring of the bridge, as they relate closely to its overall stiffness or loading capacity. A drop in any frequency of the bridge implies some deterioration in the stiffness of the structure in the global sense, which may be caused by damages in certain ...