ABSTRACT
Fastenings to concrete are implemented in a wide variety of statistically indeterminant structures such as suspended ceilings. In contrast to statistically determinant systems, failure of one fastener does not lead to direct collapse but to a redistribution of the load to adjacent fasteners. This concept can serve well in situations of high uncertainty and variance at the failure time, particularly with some level of tolerance for states of limited damage – an example is non-structural safety-critical suspended installations. Such systems can be subjected to sustained or dynamic loading. This can result in very brittle failures without any prior signs throughout the system’s life-cycle, making the safety evaluation crucial. The present study focuses on the evaluation of safety in redundant fastening systems with fatigue and corrosion effects. A computational probabilistic model is used to evaluate the life-cycle performance of a redundant installation to showcase the feasibility of this approach. The virtual system consists of anchor groups and a fatigue-relevant load in each group is determined and distributed among the anchors. Degradation of the system is also implemented by randomly assigning corrosion damage to individual elements and by reducing annually the level of prestress in the anchors. Failure of a single anchor leads to redistribution and possible progressive collapse of the system. The year of failure is collected from multiple realizations and it is evaluated statistically. The resulting probable year of element and system failure for the entire system are calculated accounting for stochastic degradation processes, and it subsequently provides the basis for inspection and maintenance plans.
