Finite Element Modeling of “Rocking Walls"

Rocking walls represent an emerging solution for lateral force resisting systems in low to medium seismicity sites. The main features of these systems are the self-centering capacity after a seismic event provided by unbonded post-tensioned tendons connecting the top of the wall to the foundation and the low damage, compared to traditional reinforced concrete shear walls, being the rocking wall placed on top of the foundation with no longitudinal reinforcing bar crossing the wall-foundation joint, thus avoiding tension in concrete. These systems accommodate displacement seismic demand by the development of a concentrated gap opening between the wall and the foundation instead of an extended plastic hinge as in traditional shear walls. The aim of the present paper is the comparison of different rocking wall finite element modeling techniques, by means of nonlinear static and dynamic analyses, in order to highlight the influence of the system damping choice on the numerical response and the differences in terms of lateral and vertical wall displacements, base shear, neutral axis variation and compressive strain at the wall toe. The finite element models considered herein are based on nonlinear brick and plane-stress plate elements, fiber beam elements, compression only springs and concentrated rotational springs.