Behaviour of Redundant Fasteners under Tension Load with Crack Cycling

In Australia and New Zealand, seismic prequalification tests and assessment methodology for post-installed fasteners are conducted in accordance with European prequalification guidelines. This demands rigorous testing of fasteners in cracked concrete with large crack widths of up to 0.8 mm. A seismic testing facility for this purpose was developed and validated at Swinburne University of Technology for the first time in the southern hemisphere. The developed testing facility was used to evaluate the seismic performance of small-sized fasteners (typically 6 mm in diameter), which are commonly used as redundant fasteners for non-structural applications such as lightweight ceilings. Such fasteners have traditionally been prequalified and designed for static and quasi-static loads only. This limits the use of redundant fasteners in seismic applications. This paper presents the tensile behaviour of 6 mm concrete screw anchors under cyclic crack openings. A series of crack cycling tests were conducted under sustained tension load with varying crack widths up to 0.8 mm. Displacement slip and temporary load drop were observed in the load–displacement behaviour of small-sized screw anchors in large crack widths.