ABSTRACT
The recent research developments regarding the utilization of time-to-failure testing as an assessment tool for the long-term behavior of bonded fasteners under sustained load raise the question of the link between the current assessment procedure (so called Findley extrapolation method) with the time-to-failure approach. The two methods are using data from tests loaded at different relative load levels. Nevertheless, both methods require sustained load tests which are analyzed with the objective of deriving the ultimate long term bond resistance. Although both methods use the same type of tests, they differ with respect to (i) the actual result of the tests (failure/no failure), (ii) the measured quantities during the tests, and (iii) the analysis. These essential differences make a direct comparison of the two approaches rather challenging. However, the link between the two methods and ultimately a comparison of the assessment that they provide is feasible when some assumptions that are supported by the literature are considered. This contribution presents a detailed comparison of the two assessment methods using the same datasets of experimental data of bonded anchors with two different adhesive mortars. The current contribution establishes a clear link between the two assessment methods. Additionally, it confirms the conservatism of the currently used approach. Finally, an optimized approach is proposed based on time-to-failure tests, which could serve as an optimized and yet still sufficiently conservative assessment method for the long-term behavior of bonded anchors under sustained loads.
