Rocking podium structures consist of rocking columns supporting a platform to achieve kinematic seismic isolation of the superstructure above. This article presents detailed finite element (FE) analysis modeling and results of the benchmark rocking podium structure that was tested as part of a blind prediction contest organized by the Pacific Earthquake Engineering Research center (PEER) at UC Berkeley, the University of Bristol, and ETH Zurich in 2019. Details of the FE modeling approach, as well as a discussion on key results and findings of this study are outlined herein. It was found that the FE model of the rocking podium structure was not sensitive to the element type, mesh layout or maximum time step, while the choice of contact algorithm influences the stability of the predicted rocking behavior. Modeling of the friction interactions between the rocking interfaces also had a nontrivial influence on the dynamic rocking response as it represented the main source of energy dissipation in the system. Further, instead of assuming an arbitrary value for inherent damping which was deemed to be very low for such a structure, explicit modeling of the frictional dissipation mechanism at the column‐to‐podium interface was preferred in this study.

This state-of-the-art review provides an overview of the evolution of self-centering structures from early historical structures that inherently exhibited a recentering response to modern systems engineered for enhanced seismic resilience. From the early research investigations that were conducted since the 1960s, to the sharp increase of interest in this topic over the last two decades, self-centering seismic-resistant structures that can mitigate both damage and residual drifts following major earthquakes have seen significant advances. These systems achieve the intended self-centering response by either allowing for the rocking of primary structural elements in a controlled manner, commonly coupled with mechanical restraints and energy dissipation devices, or by including self-centering devices as main structural or supplemental structural members. To better explain the concepts and the underlying mechanics governing their seismic response, detailed schematic illustrations were developed in this article, highlighting the fundamentals behind each of these systems. This article covers a historical overview, presents the state of the research and of the art, discusses general design challenges and practical considerations, and concludes with future research needs to advance the development and broader application of self-centering systems in real structures.

Rapid urban growth has been paired with a rapid increase in the demand for high‐rise buildings, and has accelerated the need for developing more resilient high‐rise buildings in earthquake‐prone regions. Current best practices for the seismic design of high‐rise buildings follow a performance‐based design approach that allows the designer to use innovative structural systems, select performance objectives, and verify seismic performances targeted at multiple levels of seismic intensity. As shortcomings in conventional code‐designed high‐rise buildings continue to be revealed by strong earthquakes, the importance of more resilient high‐rise systems is increasingly evident. Several high‐performance systems have been proposed to limit the excessive seismic demands attributed to higher‐mode effects in high‐rise buildings. However, these systems still face design challenges associated with distributed damage and residual deformations. This paper proposes a novel self‐centering base mechanism for high‐rise buildings that independently limits both shear forces and overturning moments at the base to mitigate higher‐mode effects, while eliminating residual deformations and controlling concentrated stresses within the structure that otherwise would need to be designed for. The schematic overview of the proposed system is first introduced, followed by the detailed design of a physical embodiment developed based on a reference 42‐story RC core wall building. Results of a numerical case‐study comparison confirm that an enhanced seismic performance is achieved through the proposed system with minimum damage and negligible residual deformations even following major seismic loading. The proposed system, with further investigations, also has the potential to be applied to a wider range of structural systems.

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As structures are built taller and more slender, their response becomes increasingly sensitive to dynamic loads that are induced by the buildings' higherfrequency vibration modes. This leads to a more complex seismic response of high-rise structures when compared to the seismic response of low-rise structures that are primarily governed by their fundamental modes of vibration. This paper presents the results of extensive shake table testing and finite element analyses of a small-scale, 1.5-meter-tall shaking table specimen that was designed and scaled to experimentally capture the higher-mode effects of a 125-meter-tall reference tall building. The test specimen is comprised of a simplified superstructure with uniform mass and stiffness representing the main structure of the full-scale reference tall building, and a base-rocking mechanism to represent the moment-limiting effect of the inelastic plastic-hinging mechanism at the base of the reference building. Using the methodology proposed in this paper, the scaled specimen was shown to exhibit similar seismic response characteristics, including the corresponding higher-mode effects, along the height of the structure as those predicted numerically on the full-scale reference building. Results of the shaking table tests experimentally provided further evidence that relying only on a moment-limiting mechanism at the base of a cantilever structure is insufficient in limiting peak seismic loads due to higher-mode effects. In addition, by comparing test results with predictions obtained using several previously proposed analytical methods, the paper demonstrated that predicting shear force amplifications due to higher-mode effects is still challenging. The methodology developed in this study can be used to design other similar small-scale shaking table tests for the development of new analytical methods to predict higher mode effects and experimentally validate the efficiency of new high-performance systems developed to mitigate higher-mode effects on tall and slender structures and more generally to assess the ability of these systems to achieve enhanced seismic resilience.