Michalis F. Vassiliou

Allowing structural systems to uplift and rock during seismic excitation has emerged as an effective and inherently self‑centering form of seismic isolation. This paper develops a computationally efficient 3D analytical model suitable for the understanding of the behavior of rocking bridges. The model comprises a rigid slab supported by rocking columns of square cross section that can uplift and rock in two horizontal directions, while not sliding, twisting or stepping out of their original position. The equations of motion are derived, impact damping is determined, and rocking spectra are generated under 176 bidirectional pulse‐like ground motions. The study proves the existence of an equivalent solitary rocking column with identical slenderness yet larger size whose dynamic response closely matches that of the podium structure—similarly to the planar case. A statistical evaluation of the ground motions shows that PGV / T _p is a more efficient acceleration scale than PGA for the description of the 3D rocking motion. A displacement‑based assessment further proves that, provided the system does not approach overturning, the displacement demand depends only on slenderness and is independent of column size. The above supports the development and use of unified, size‑independent 3D rocking spectra, simplifying the design parameters of 3D rocking structures.

A three‐dimensional analytical two‐degree‐of‐freedom (2DOF) model is developed to describe the bounded rocking response of free‐standing rigid square columns subjected to bidirectional seismic excitation. The formulation extends Housner's classical planar theory by deriving the full three‐dimensional equations of motion for a column constrained to rock only within its original footprint, so that it can be used to model a rocking bridge column. Energy dissipation is introduced exclusively through instantaneous, inelastic impacts occurring during transitions between edges and corners, assuming angular momentum conservation. Three distinct impact mechanisms are identified and incorporated into a numerical integration framework capable of capturing transitions between rest, edge rocking, and corner rocking. The resulting motion exhibits strong coupling between orthogonal rotations and energy transfer between rocking directions during impacts. A comparative statistical study involving 176 near‐fault, pulse‐like ground motions demonstrates that square columns dissipate more energy and are, thus, more stable than their cylindrical counterparts, indicating superior inherent stability and enhanced impact‐induced damping capacity.

This data paper presents a comprehensive dataset derived from a series of 29 centrifuge shake table tests of 29 identical virgin small‐scale physical models of an unreinforced masonry (URM) structure. System‐level testing of full‐scale civil engineering structures under seismic loading is often prohibitively expensive and time‐consuming due to specimen size and facility requirements. To address these limitations, focusing on global‐level assumptions in modeling earthquake behavior, the small‐scale (1:15) models of the URM structure were tested in the ETH Zurich geotechnical centrifuge to preserve similitude. The models were produced using additive manufacturing (3D printing) technology to create masonry‐like elements. The microgeometry of the printed elements was modulated to physically simulate mortar joints, allowing for testing of a model comprising a single printed material as a surrogate for traditional masonry. The paper describes the specimen and the experimental setup, the applied ground motions and scaling principles, the instrumentation, and key test results, including the observed failure modes. The related dataset is publicly available through the ETH Research Collection platform and is systematically organized. Examples of extracted raw data, including time histories of input motion and sensor measurements, as well as response spectra, are presented for both a failed and a non‐failed structure. The dataset is intended to serve as a benchmark for the validation of system‐level assumptions in analytical and numerical models of URM structures subjected to seismic loading. Its potential for reuse includes comparing different modeling approaches, structural identification studies, educational purposes, and enhancing the understanding of seismic vulnerability in historical URM.

Thick rubber bearings (TRBs) have been proven to be effective in mitigating horizontal shaking induced by earthquakes as well as railway-induced vertical vibration. During earthquake excita...