ABSTRACT
Anchorages to concrete are very often realised through a group or system of fasteners connected through a fixture. In such cases, the individual fasteners’ load-bearing performance can be characterised by a highly non-linear interaction with the other components in the group. This interaction is observed at two levels in the design, namely (a) the distribution of forces to the individual anchors, and (b) the mutual strength deprivation of individual fasteners in close proximity. Furthermore, failure of a fastener in a group can occur in-dividually, leading in progressive damage or failure of the group, namely due to: (a) a load effect: one of the anchors may receive a higher load compared to the others depending on the load direction and combinations, and (b) a resistance effect: one of the anchors is located closer to a free edge, and/or the substrate material is locally weaker, and/or the anchors was installed with a defect. Consequently, only component load redistribution and progressive failure considerations can allow for an adequate assessment of the structural safety for such systems. This paper discusses the utilisation of robustness measures and principles on assemblies with redundant fastenings in concrete. Investigation results and failure situations are presented, which highlight the significance for the concepts mentioned above, and a respective case study for the robustness assessment of a group of bolted anchors to concrete is delivered.
