Design of Thick Concrete Plates Using Strut-and-Tie Model

A strut-and-tie model is developed to model the punching shear behavior of thick concrete plates. This model provides a quick and simple approach to punching shear behavior. It is applicable to both normal- and high-strength concrete under symmetric and nonsymmetric loading with and without shear reinforcement. The strut-and-tie model for symmetric punching consists of a "bottle-shaped" compressive zone in the upper section of the slab depth, leading to a "rectangular-stress" compressive zone in the lower section depth. An equation based on failure criteria for the strut-and-tie method is used to model the behavior in the lower compressive stress zone. Another strut-and-tie model is also developed to rationally model nonsymmetric punching shear behavior due to unbalanced moment transfer and symmetric punching behavior of concrete slabs with shear reinforcement. The results of the strut-and-tie models for symmetric and nonsymmetric loading with and without shear reinforcement were compared to experimental test results performed and published by others. The results of the strut-and-tie models showed excellent agreement with available test results.