No abstract

No abstract

Summary A new model is presented for multiblock columns subjected to earthquakes, which contains an impact and an opening model. Both in the impact and in the opening model, all the possible opening configurations are investigated because it was found that in many practical cases, unexpected patterns may occur. The model is purely mechanical: assuming rigid blocks and classical (inelastic) impact. The effect of energy dissipation during impact was investigated. Using our model in accordance with the literature, it was found that monolithic blocks are more vulnerable to overturning than multiblock systems.

Summary A new model is presented for planar multi‐block arches subjected to earthquakes. The blocks are assumed to be rigid, and every interface between the blocks may split open and may close, ie, the blocks may impact to each other. During impact, both the classical Housner's approach and improved models with lower energy dissipation are considered. The arch model is verified by comparisons with the available results in the literature. Using the new model, it was found that the circular arch moves as a four‐hinge mechanism typically only at the beginning of excitation, and several cracks split open during motion; furthermore, that modeling a multi‐block arch by a single degree of freedom (SDOF) four‐hinge mechanism may significantly overestimate its collapse load. While, in accordance with the literature, the overturning curves of single blocks and arches with symmetrically located four hinges are similar; for multi‐block arches where several hinges may occur they can be very different.

Studies of rocking motion aim to explain the remarkable earthquake resistance of rocking structures. State-of-the-art assessment methods are mostly based on planar models, despite ongoing efforts to understand the significance of three-dimensionality. Impacts are essential components of rocking motion. We present experimental measurements of free-rocking blocks on a rigid surface, focusing on extreme sensitivity of impacts to geometric imperfections, unpredictability, and the emergence of three-dimensional motion via spontaneous symmetry breaking. These results inspire the development of new impact models of three-dimensional facet and edge impacts of polyhedral objects. Our model is a natural generalization of existing planar models based on the seminal work of George W. Housner. Model parameters are estimated empirically for rectangular blocks. Finally, new perspectives in earthquake assessment of rocking structures are discussed.