Non-linear analyses of reinforced concrete elements with pronounced slips of longitudinal bars

The paper shows results of two non-linear cyclic analyses performed with OpenSees where slippage phenomenon of longitudinal bars is pronounced. Bond-slips have modeled by using the simplified model proposed by Braga et al. which assigns an equivalent stress-strain relationship to longitudinal steel accounting for both material elongation and relative slip. The model is also capable to take into account anchorages at bars ends (such as bends or hooks) and has been developed mainly for assessing older existing buildings where, because of the presence of reinforcing plain bars, bond-slips are particularly pronounced. Unlike many other refined models published in literature, the analytical formulation of the proposed model requires a minimum computational effort avoiding any nested iterations loop in the context of fiber model discretization of a section.