A self-centering multilevel rocking wall-frame system for mitigating seismic damage in precast concrete buildings

In order to improve seismic resilience and reparability of precast concrete buildings, different forms of rocking wall building systems have been proposed in recent decades. The base-rocking single wall-panel system incurs limited damage under lateral loading, but it experiences high floor acceleration and storey forces for mid- and high-rise buildings due to the effect of higher vibration modes. A multiple-rocking wall system has been proposed to reduce the effect of higher modes in storey forces, but this system leads to larger drifts, thereby increasing the damage to drift-sensitive non-structural elements. To overcome these limitations, the present study proposes a Self-centering Multilevel Rocking Wall-frame (SMRW) system that simultaneously reduces all forms of seismic demands. The SMRW system consists of multiple small rocking wall units, semi-rigid horizontal precast concrete panels and post-tensioned base-rocking boundary columns at each floor level. To enhance the energy dissipation capacity of the proposed system, external tension-compression yield steel dampers are provided across each rocking interface. Superior seismic behaviour of the proposed SMRW system is validated by comparing the seismic performance of 3, 9, 15 and 21-storey building models with the proposed SMRW system together with the base-rocking, multiple-rocking and conventional cantilever structural wall systems. For this purpose, nonlinear static and dynamic (time-history) numerical analyses are conducted on the building models using finite-element and fiber-element modelling, which are validated using experimental results. As the numerical results demonstrate, the proposed SMRW system, while being a low-damage system, can simultaneously mitigate the inter-storey drift, floor acceleration and storey forces/moments compared to other systems. Therefore, the proposed SMRW system can significantly reduce seismic damage to a building's structural and non-structural elements, and can offer a truly low-damage option for mid and high-rise buildings in seismic regions.