Rational Shear Modulus for Smeared-Crack Analysis of Reinforced Concrete

Over the past 30 years, theories for predicting the nonlinear behavior of reinforced concrete under shear have developed to a state where they can satisfy the stress equilibrium, the strain compatibility and the constitutive laws of materials. A case in point is the fixed-angle softened truss model (FA-STM) in which the constitutive laws of cracked concrete include the stress-strain relationships in compression and tension, as well as the stress-strain relationship in shear. Despite these advances, the FA-STM still employs a very complicated shear stress-strain relationship of concrete that is obtained empirically and thus imposes a tedious, two-phase solution algorithm. This paper presents a new rational shear modulus for the FA-STM based on the smearedcrack concept. This rational, yet very simple, modulus not only greatly simplifies the solution of the FA-STM but also improves its accuracy. Moreover, this new shear modulus can be used widely to replace the many complicated empirical constitutive laws for shear of cracked concrete, as employed in the various nonlinear analyses of reinforced concrete structures. A notable example is the finite element analysis.