Load capacity of squat RC shear walls by strut-and-tie model

Abstract

A simplified strut-and-tie model (STM) is established, based on the crack band theory of fracture mechanics for evaluating the lateral load capacity of squat reinforced concrete (RC) shear walls. The load transfer mechanism of concrete is identified by the strut-and-tie action contributed by the web concrete and longitudinal reinforcement of the boundary elements of the walls, whereas that of shear reinforcement is identified by the tie action idealised using a statically indeterminate truss system. The load transfer capacities of the concrete strut and shear reinforcement are driven using the energy equilibrium in the stress relief strip and the crack band zone formed along a diagonal crack. The width of the main concrete strut is determined using the neutral axis depth simplified as a function of the longitudinal reinforcement ratio and the elastic modulus ratio between concrete and reinforcing bars. Predictions made by the proposed model are in better agreement with test results compiled from 150 specimens than those made by other models. The comparison also reveals that other empirical equations provided by ACI 318-14, Wood, and Gulec and Whittaker significantly underestimate the lateral load capacity of squat shear walls, whereas the STM proposed by Siao overestimates the load capacity.