Timber bridge evaluation: A global nondestructive approach using impact generated FRFs

Bridges require periodic inspections to ensure the safety of those using the structure. A visual inspection has historically been the most common form of investigation for timber bridges. This poses many problems when inspecting bridge timbers since often the damage is internal, leaving no visible signs of decay on the surface. Localized nondestructive evaluation (NDE) techniques have been developed to allow assessment of the internal parts of timber structural members. Testing an entire structure in this manner can be tedious and time consuming. Steel structures have long been tested from a global perspective, basing the assessment of health of the structure on modal parameters, This paper presents an effort to extend global testing methods, specifically impact testing, to timber bridges.