Numerical study of a multiple post-tensioned rocking wall-frame system for seismic resilient precast concrete buildings

A multiple rocking wall-frame(MRWF)system,in which the wall panels are directly connected to the adjacent beams and foundation is presented herein.In the MRWF system,the unbonded post-tensioned(PT)tendons are used to promote the self-centering ability,and O-shaped steel dampers are applied to enhance the energy dissipation capacity and reparability of the structure.First,analytical equations are proposed to determine the behavior of the O-shaped dampers.Then,the MRWF system is numerically evaluated for five different models consisting of rocking walls with varying numbers and arrangements while keeping the total effective width of wall panels constant.The numerical results show that with an increase in the number of wall panels and a decrease in the wall width,the hysteretic behavior of the MRWF system tends to the ideal flag-shaped pattern,resulting in little damage to the beams,insignificant strain in the wall toe,negligible residual drifts and damage index of less than 0.2 under severe earthquakes.In contrast,the conventional model demonstrates extensive damage to the structural elements due to undesirable wall-to-frame interaction,which leads to a damage index of 0.78 and residual drifts of 0.42%under seismic loads.

Behaviour of self-centring shear walls——A state of the art review

The application of unbonded post-tensioning (PT) in structural walls has led to the development of advanced self-centring (rocking) shear wall systems that has significant advantages, including accelerated construction due to the incorporation of prefabricated elements and segmental construction for different materials (e.g., concrete, masonry, and timber), reduced residual drifts, and little damage upon extreme seismic and wind loads. Concrete, masonry, and timber are often used for the construction of unbonded PT structural wall systems. Despite extensive research since the 1980s, there are no well-established design guidelines available on the shear wall configuration with the required energy dissipation system, joint’s locations and acceptance criteria for shear sliding, confinement, seismic performance factors, PT loss, PT force range and residual drifts of shear walls subjected to lateral loads. In this research a comprehensive state-of-the-art literature review was performed on self-centring shear wall system. An extensive study was carried out to collect a database of 100 concrete, masonry, and self-centring shear wall tests from the literature. The established database was then used to review shear walls’ configurations, material, and components to benchmark requirements applicable for design purposes. The behaviour of concrete, masonry and timber shear walls were compared and critically analysed. The general behaviour, force-displacement performance of the walls, ductility, and seismic response factors, were critically reviewed and analysed for different self-centring wall systems to understand the effect of different parameters including configurations of the walls, material used for construction of the wall (concrete, masonry, timber) and axial stress ratio. The outcome of this research can be used to better understand the behaviour of self-centring wall system in order to develop design guidelines for such walls.