Experimental Evaluation of the Cyclic Behaviour of Different Smooth Rebar Anchoring Layouts

The existing reinforced concrete frame structures built before the 1970s were designed only for gravity loads, and they were mainly built using smooth steel rebars. The behaviour of these kinds of structures is different with respect to that exhibited by structures reinforced with deformed rebars. Low bond capacity and the associated slip of the anchorages characterise a more flexible structural response and a lower energy dissipation of the elements. The contribution of rebar slip to structural deformability is often not considered in traditional lumped plasticity models used for the assessment of existing structures. An innovative modelling approach has been recently proposed to directly account for smooth rebar slip, so the characterization of the cyclic behaviour of different types of anchorages is of primary importance. A first experimental campaign was conducted on straight, hooked-end, and bent anchorages to evaluate their hysteretic behaviour and their strength capacity. Some aspects highlighted by the first campaign were investigated in the second one, the main results are here presented. The influence of the bond conditions and of the embedded length on the anchorage performance of plain rebars was investigated, and the mean bond strength was thus evaluated. Finally, the cyclic behaviour of bent anchorages for different bond conditions is analysed.