Nonlinear Analysis of Beams Reinforced in Shear with Stirrups and Steel Fibers

Experimental four-point bending tests on steel fi ber-reinforced concrete (SFRC) beams were performed and the complete loadversus- displacement curves were predicted by suitably adapting a nonlinear fi nite element code for plain and reinforced concrete (RC) elements to the analysis of SFRC structural members, based on the modifi ed compression fi eld theory (MCFT) and the disturbed stress fi eld model (DSFM). The effect of steel fi bers on shear-fl exure response is taken into account, mainly by incorporating appropriate tensile and compressive stress-strain analytical relationships for SFRC and introducing several modifi cations in the theoretical models to cover local conditions at crack. The numerical results show the model’s effectiveness to predict the structural response of both specimens reinforced with steel fi bers only and beams with stirrups and steel fi bers as transverse reinforcement. The experimental and numerical results highlighted the capacity of steel fi bers to partially substitute the stirrups as shear reinforcement in beams and demonstrated how the coupled transverse reinforcement, provided by stirrups and steel fi bers, is an optimum solution both in terms of structural performance and costs.