A Review Of Non-Destructive Test Methods: Appropriate Choice Of A Method For Use With Timber Beam Bridge Girders

Timber bridges were built extensively throughout Australia, in the 19th and 20th centuries and over 2500 are still in use on rural roads in New South Wales. For many of these bridges degradation may have occurred and it is difficult to determine the carrying capacity of an apparently degraded structural timber element and the subsequent need for maintenance or replacement. This review examined commercially viable non-destructive methods of evaluation. Although some techniques hold promise for future application, such as optical fibre techniques, none was currently found to be entirely suitable for use with both new and aged timber beam bridge girders. A novel laser based technique was developed to provide a low cost measurement system that could be easily retrofitted to both old and new structures to provide a continuous indication of timber bridge girder performance. Extensions of this technique are also applicable to other large beams constructed from a variety of materials such as concrete, steel and engineered timber.