The Impact Vibration Test is now regarded as a method to evaluate the conditions of bridge substructures. This method focuses on the natural frequency of the pier under test, since it clearly shows the condition of the bearing capacity of the foundation and the soundness of the pier. Compares the measured and standard values of the natural frequency of the pier for judgement, and judges it as "sound" when the former is sufficiently higher than the latter and as "unsound" otherwise. The standard value of the natural frequency is calculated by statistical analysis by using several parameters, such as the height of the pier, weight of the superstructure and width of the pier. Although these parameters are highly correlated with the natural frequency, they do not have physical significance at all. Wholly based on the design concept for foundations, this paper introduces a new and progressive idea for the standard value of the natural frequency of the timber pile foundations.

Copyright (c) 2003 Railway Technical Research Institute