Finite Element Modelling of Structural Concrete

Over the years a large number of finite element analysis programs have been developed in order to investigate the behaviour of reinforced concrete (RC) elements and structures. These are based on the use of a wide range of concrete material laws, the majority of which can be classified as empirical, plastic, visco-plastic, damage and hybrid, depending on the theory or combination of theories upon which their analytical formulation is based. The formulation of most, if not all, of these material models relies heavily on a number of empirical parameters, the inclusion of which is essential for defining material behaviour. These parameters are usually linked to post-peak concrete characteristics such as, for example, strain softening, tension stiffening, shear-retention ability, etc, coupled with stress- and/or strainrate sensitivity when high-rate loading problems are considered; their values often vary depending on the type of problem investigated.
Three widely used packages, (LS-DYNA, ANSYS and ABAQUS), are adopted in the present work in order to investigate analytically the experimental response of simply supported RC beams under monotonic loading applied at various rates, ranging from static and earthquake to rates encountered in impact and blast problems. A fundamental assumption adopted in the case studies investigated herein, is that for the case of high-rate-loading, concrete constitutive behaviour is essentially independent of the loading rate and that the effect of the latter on
structural response can be primarily attributed to inertia forces. The predictions obtained are compared with published experimental data as well as the predictions of a specialized in concrete structures analysis package (RC-FINEL), which, in contrast with the above packages, incorporates a fully brittle material law for the constitutive description of concrete behaviour under triaxial loading. The aim of the present investigation is to explore the generality and applicability of the FE models presently adopted and their ability to yield realistic predictions
of structural concrete behaviour.