DESIGN-ORIENTED APPROACH FOR STRAIN-SOFTENING AND STRAIN-HARDENING FIBRE HYBRID REINFORCED CONCRETE ELEMENTS FAILING IN BENDING

In the present paper a design oriented model is proposed to evaluate the flexural resistance of elements of fibre reinforced concrete (FRC) of tensile strain-softening or tensile strain-hardening behaviour and strengthened longitudinally by steel bars in the tensile zone of a rectangular cross section. The cross sectional moment-curvature response predicted by this model is used in a numerical approach to predict the load-deflection relationship of beams failing in bending To appraise the predictive performance of this approach, the results obtained in an experimental program with shallow beams of steel fibre reinforced self-compacting concrete and strengthened with distinct reinforcement ratios are compared to those estimated by the developed model. The predictive performance of the model is quite satisfactory, taking into account the simplified approaches adopted in order to have a closed form solution that can be used in the scope of design FRC elements failing in bending.