ABSTRACT
A great deal of time, effort and expense can be wasted on in-situ testing unless the aims of the investigation are clearly established at the outset. These will affect the choice of test method, the extent and location of the tests and the way in which the results are handled – inappropriate or misleading test results are often obtained as a result of a genuine lack of knowledge or understanding of the procedures involved. If future disputes over results are to be avoided, liaison of all parties involved is essential at an early stage in the formulation of a test programme. Engineering judgement is inevitably required when interpreting results, but the uncertainties can often be minimized by careful planning of the test programme. A full awareness of the range of tests available, and in particular their
limitations and the accuracies that can be achieved, is important if disappointment and disillusion is to be avoided. Some methods appear to be very simple, but all are subject to complex influences and the use of skilled operators and an appropriately experienced engineer is vital. In-situ testing of existing structures is seldom cheap, since complex access
arrangements are often necessary and procedures may be time-consuming. Ideally a programme should evolve sequentially, in the light of results obtained, to provide the maximum amount of worthwhile information with minimum cost and disruption. This approach, which requires ongoing interpretation, will also facilitate changes of objectives which may arise during the course of an investigation.
