Analysis of Entire Load-Deformation Process of Shear Span Ratio Not More Than 2.0: Reinforcement of Concrete Squat Walls by Strut-Tie Model

An improved strut-and-tie model that considers the deformation compatibility for determining the load-deformation relationship for squat walls (shear span ratio smaller than 2.0) is proposed. The model originates from the strut-and-tie model, and it includes a diagonal concrete strut, secondary concrete struts, subsidiary concrete struts, horizontal tie, vertical tie, and shear reinforcement ties. A definite equation between the deformation of two types of concrete struts (a diagonal concrete strut and four secondary concrete struts) and the displacement of the squat walls is given. The relationship among compatibility, equilibrium, and constitutive laws in each of the strut and ties was established. In addition, parameter analyses were conducted using the improved strut-and-tie model to study the effect of axial load, aspect ratio, and distribution reinforcement ratio on the skeleton curves of shear walls. The results show that, compared with the test results for six shear walls, the forces and deformations of the predicted members' are in reasonable agreement with test results. During parameter analysis, when the axial load ratio increases from 0.1 to 0.5, the maximum growth of load-carrying capacity is 27%. As the aspect ratio of shear walls increases from 1.0 to 2.0, the load-carrying capacity decreases 30%. As the distribution reinforcement ratio increases from 0.25% to 0.55%, the load-carrying capacity increases only 6%. The effect of the distribution reinforcement ratio on load-carrying capacity is not significant compared with the other two parameters.