Contributi Resistenti a Taglio nei Nodi Interni Soggetti ad Azione Sismica

The behaviour at failure of 266 beam-column joints tested by various authors has been examined to identify a model for computing the shear strength of internal beam-column joints under severe seismic actions. This exam has pointed out that during the cyclic loading a large diagonal cracking comes together with a joint volumetric expansion. Four resisting contributions to joint expansion have been identified: the concrete one, the beam longitudinal reinforcement one, the beam constraints contribution against the horizontal joint expansion, and the stirrup one. The overall shear strength has been taken as the sum of these four contributions, each dependent on a multiplying factor which has been univocally determined on the experimental available data. The obtained expression predicts the shear strength in a more accurate and uniform way than the Eurocode and ACI Code expressions.