Costruzioni di Cemento Armato: Analisi Mediante un Modello di Danno

a two parameters scalar damage model developed by Farja and Oliver (1998) for brittle materials like concrete, undergoing general tensile and compressive stresses, is briefly recalled. The adoption of two independent scalar damage parameters, d+ which grows for tensile stress and d- which oppositely affects the compressive part of the stress tensor, allows to consider a peculiar behaviour of concrete structures: the stiffness recovery at crack closure under alternate strain conditions. The damage model has been implemented into a numerical finite element code (Scotta, 1997), including also the representation of the elasto-plastic reinforcement steel. The F.E. code performs the static and dynamic non linear analysis of reinforced concrete structures. The effectiveness of the proposed model has already been demonstrated in previous works (Saetta e al, 1998a,b). The result of its application to the analysis of two complex r.c. structures, a frame and a wall, both designed according to EC2 and EC8, are here described. As shown in Fig. 1 for the r.c. wall analysis, the model predicts the tensile and compressive damage patterns on concrete and the plastic deformation map of the reinforcement.