Shear strength of squat walls: A strut-and-tie model and closed-form design formula

Reinforced concrete squat walls, with height less than twice the length, are key structural elements for seismic resistance in many structures. Design formulas available in building codes and literature showed substantial scatter in shear strength predictions and do not include all variables that affect squat walls response. A closed-form expression that accounts for the shear strength contributions provided by the diagonal concrete strut and the web reinforcement is derived, while considering those variables that significantly affect the behaviour of such walls. Model parameters were calibrated using the experimental results of 664 rectangular and flanged walls available in the literature. The proposed model is compared to a number of predictive equations for the shear strength of squat walls, and it results as the one best fitting the measured shear strengths. Further, a design formula, suitable for implementation in codes and standards, is proposed.