Finite element modelling of a RC rocking wall with additional steel rebars

Hybrid walls, i.e. rocking walls with additional energy dissipation, represent a valid lateral force resisting system in seismic regions, due to the limited seismic damage experienced by this system and to the self-centering ability provided by unbounded post-tensioned tendons. These systems accommodate the displacement seismic demand by the development of a single gap opening at the wall base. A sensitivity analysis of the various parameters has been carried out with the purpose to evaluate their influence on the finite element dynamic response of a selected case study. Three types of models are considered in order to describe the behaviour of the wall-foundation interaction: fiber beam elements, compression-only springs and lumped rotational spring. The main parameters investigated are the damping model and damping magnitude, the elastic modulus of the concrete at the wall-foundation interface, the stiffness and number of the compression only springs, the unbonded length of the rebars used as dissipating device and their hysteresis model. The sensitivity analysis was carried out with the OpenSees finite element software and allowed to preliminary address the influence of the selected parameters by comparison with a reference case study.