Reinforced concrete corbels - Shear strength model and design formula

A new model for determining the shear strength of reinforced concrete (RC) corbels, or brackets, is proposed in this paper. The model is obtained by superimposing the shear strength contribution of the strut-and-tie mechanism due to the cracked concrete and principal reinforcement, and the strength contribution due to stirrups. The first contribution is expressed by means of a limiting shear strength expression, whereas the second is derived from the equilibrium of the strut-and-tie mechanism in the presence of stirrups. An explicit formula dependent on two coefficients is derived for the shear strength of corbels. These two constants are calibrated on the results of 243 test data, which can be found in the relevant literature. The expression obtained in this way is compared to the ACI Code and the most recently proposed formulas and computing procedures, and it results as better fitting the measured shear strengths. On the basis of results of this paper, a design formula is proposed.