Fatigue behaviour of hybrid grouted joints under axial loading

Steel constructions made of circular hollow sections are commonly joined by welding or ring-flange bolting. An additional, novel joining method is the so-called hybrid grouted joint. The hybrid grouted joint is characterised by its multi-layered composition. In contrast to state-of-the-art grouted joints, hybrid grouted joints include thin adhesive layers, which are applied on the steel surfaces prior to grouting. Sand grains are embedded in the yet uncured adhesive. After the curing of the adhesive, the surface has a high degree of roughness. This allows a high-performance interlock between fine grain grout and the adhesively bonded sand granules across the contact surfaces in the overlap area. The ability to transfer loads across a wide area with low stress concentrations makes the hybrid grouted joint a promising joint alternative especially regarding the fatigue performance. This paper summarises the main findings concerning fatigue behaviour of the hybrid grouted joint under axial loading. Wöhler diagrams were determined in numerous fatigue tests for two combinations of adhesive and grout.