A simple shear wall model taking into account stiffness degradation

The damage undergone by reinforced concrete structures affects their modal characteristics. The study consists of constructing an original simplified model for a heavily reinforced shear wall relying on modal characteristic changes related to a damage increase. The elaboration of this simplified model is realised in several stages. The first stage is devoted to the inelastic finite element analysis of a shear wall which was tested under pseudo dynamic loading. Then, by applying a set of ideal excitations to the two-dimensional finite element modelling, the identification of the decrease of the fundamental frequency as a function of a damage variable is carried out. The third stage is concerned with constructing a new uniaxial dynamic model by introducing directly the expression of the decrease of the fundamental frequency into the equation of motion. Finally, the validity of the simplified modelling is assessed by comparing the numerical results obtained from the finite element analysis with those derived from the simplified analysis, for different types of seismic excitation.