HAUNCH RETROFIT OF RC BEAM-COLUMN JOINT: FASTENING ASSESSMENT

Haunch retrofit of RC beam-column joint is made, essentially, by introducing steel diagonal elements at the beam-column joint location to reduce the shear demand in seismic deficient RC frames. Steel-to-concrete connection is often made using groups of post-installed fasteners, e.g. bonded anchors. This paper addresses the evaluation of anchor’s forces using a two-steps structural analysis. First, haunch’s diagonal force is evaluated by applying strut-and-tie model to the beam-column sub-assemblage. Second, a FEM model is employed for the sub-structure formed by the steel haunch and anchorages. Validation of both the structural analysis steps is made with respect to experimental results (e.g. measured anchors’ forces, reinforcement strains) obtained by the Authors and published elsewhere. Agreement is found when numerically-derived internal forces are compared to experimental ones. Finally, some suggestions are given for practical design cases where estimated forces need to be compared to nominal concrete break-out.