TABLE OF CONTENTS One of the most important characteristics of concrete is its low tensile strength, which results in tensile cracking at very low stress compared with compressive stresses. The tensile cracking reduces the stiffness of the concrete and is usually the major contributor to the nonlinear behavior of reinforced concrete structures, like panels and shells, where the stress is predominantly the biaxial tension-compression type. For these structures, accurate modeling of cracking behavior of concrete is undoubtedly the most important factor, and linear-elastic fracture models have been developed and used by many investigators to study the nonlinear response of reinforced concrete beams, panels, and shells.
The abrupt strain softening characteristic of the elastic brittle-fracture behavior of concrete in a tensile-stress field induces the cracking and causes sudden changes in local stress levels. This crack development and subsequent stress redistribution have a major influence on the basic behavior of reinforced concrete structures. Furthermore, such behavior imposes severe demands on any nonlinear solution technique due to the extreme strain-softening nature of crack development.
This chapter models the concrete as a linear-elastic brittle-fracture material, develops constitutive models for uncracked and cracked concrete based on the theory of linear elasticity, and addresses the problem of predicting the development of tensile cracking and estimating its influence on the behavior of concrete structures. In the subsequent chapters the nonlinear response of concrete under multiaxial com-pressive stress states is described...
