Shear models of Rc-encased steel joist beams in MRFs

This study presents the application of different analytical and finite element (FE) models aimed at predicting the shear resistance of reinforced concrete (RC) and reinforced concrete-encased steel joist (HRCESJ) beams with inclined transversal reinforcement in moment resisting frames (MRFs). In particular, four analytical models are taken into account, two of them specifically conceived for HRCESJ beams in seismic area. The analytical models considered are Eurocode-2 model for the shear strength of RC beams; a variable-inclination stress-field approach; a strut-and-tie additive model and, finally, an analytical formulation in which the shear capacity depends on the number of pairs of inclined stirrups able to yield before concrete crushing. The models are validated against a large experimental and FE dataset covering a wide range of characteristic parameters of the beam typology. The results obtained are discussed in order to stress the influence of different key assumptions adopted in both FE and analytical approaches.