Validity of the Beta Method to determine pile damage

In 1979 the Beta Method of pile integrity was published. The basic idea behind this method is that stress waves propagating
through a foundation pile will be reflected on cracks in concrete piles. As the crack becomes more extensive, so do the
reflections. In the ultimate situation of a fully cracked pile, no waves will travel through the crack and the stress wave will
be fully reflected. The Beta Method is then calculating the reflection rate (reflected as percentage of the original peak force)
and the outcome is presented as a reliable integrity indicator. However, from both theory and practical experience it can
be shown that applying the beta method to indicate pile damage will give false negative and false positive results. The
former is unwanted because sound piles will be rejected, which will cause grief to the piling contractor. The latter will
result in the fact that damaged piles are accepted as sound, where that shouldn’t be the case, obviously increasing the risk
of failure. The paper will once again illustrate this, through theory as well as practical examples, and then conclude by
making suggestions for a practical pile damage assessment on a job site using low strain dynamic testing.