Rocking and Sliding of Unanchored Bodies Subjected to Seismic Load According to Conventional and Nuclear Rules

Schau, Henry; Johannes, Martin

doi:10.7712/120113.4805.c1065

Cited by 5 publications

(6 citation statements)

References 17 publications

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“…(19). Some studies have stressed a dependence of on the interface materials [13], the amplitude of oscillation [14] and the velocity immediately before the impacts [15].…”

Section: Energy Dissipation At Impactmentioning

confidence: 99%

Semi-active control of the rocking motion of monolithic art objects

Ceravolo

Pecorelli

Fragonara

2016

Journal of Sound and Vibration

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The seismic behaviour of many art objects and obelisks can be analysed in the context of the seismic response of rigid blocks. Starting from the pioneering works by Housner, a large number of analytical studies of the rigid block dynamics were proposed. In fact, despite its apparent simplicity, the motion of a rigid block involves a number of complex dynamic phenomena such as impacts, sliding, uplift and geometric nonlinearities. While most of the current strategies to avoid toppling consist in preventing rocking motion, in this paper a novel semi-active on-off control strategy for protecting monolithic art objects was investigated. The control procedure under study follows a feedback-feedforward scheme that is realised by switching the stiffness of the anchorages located at the two lower corner of the block between two values. Overturning spectra have been calculated in order to clarify the benefits of applying a semi-active control instead of a passive control strategy. In *Manuscript Click here to download Manuscript: Manuscript.docx Click here to view linked References

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“…(19). Some studies have stressed a dependence of on the interface materials [13], the amplitude of oscillation [14] and the velocity immediately before the impacts [15].…”

Section: Energy Dissipation At Impactmentioning

confidence: 99%

Semi-active control of the rocking motion of monolithic art objects

Ceravolo

Pecorelli

Fragonara

2016

Journal of Sound and Vibration

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“…Equalling Eqs. (14) and (17) , a relationship between the velocity immediately before and after the impact is found:…”

Section: Energy Dissipation At Impactmentioning

confidence: 96%

Comparison of semi-active control strategies for rocking objects under pulse and harmonic excitations

Ceravolo

Pecorelli

Fragonara

2017

Mechanical Systems and Signal Processing

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“…The fundamental motion stages that describe the displacement of rectangular rigid bodies (blocks) in space are the following: translation, rotation (rocking), sliding and rest [40], [70]. Combinations can also occur where each motion can be described separately.…”

Section: Problem Descriptionmentioning

confidence: 99%

“…Baratta & Corbi [21] introduced a distributional expression of the displacement impulsive reactions to derive a unified formulation of the equations of the rocking motion of a rigid body under dynamic excitation, treating damping effects as a consequence of the impulsive forces. Schau & Johannes [70] applied the Finite Element method to compare its predictions with results from the numerical integration of the analytic equations of free rocking motion. The FE analysis showed that any variation from the ideal rectangular geometry of the block cause higher restitution coefficients than those obtained by Housner's model.…”

Section: Introductionmentioning

confidence: 99%

Fractal-like overturning maps for stacked rocking blocks with numerical and experimental validation

Anagnostopoulos

Norman

Mylonakis

2019

Soil Dynamics and Earthquake Engineering

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A novel, compact mathematical formulation is presented to describe the dynamic rocking response of single and double block systems subjected to gravity and/or ground excitation. The derivation of the closed-form solutions for impact and motion is based on the Euler-Lagrange equation and the conservation of angular momentum, and combines all the different cases of possible block relative rotating and impact modes (16 in total) into a single set of equations without the need of transient expressions. The derived equations that describe the impact modes are the equivalent to the expression derived by Housner and depend on the angular velocity of the blocks before impact. The analytical model is integrated numerically via an ad hoc algorithm and its reliability & accuracy are verified after various self-consistency tests and comparisons with the literature. In addition, several shaking table experiments were conducted in EQUALS laboratory in Bristol, setup constructed to test free and forced rocking motion of single and double block configurations. The error margins of the measurements are determined, and the extracted data are in good agreement with the numerical results for most examined cases. The ideal Housner restitution coefficient of single block impact to a rigid base is adjusted to match experimental conditions, and it is found to be correlated with the block aspect ratio. The forced rocking of a two-block system is shown to exhibit numerous different response patterns depending on the excitation conditions. The integrated model is finally applied to produce normalised overturning maps for double block systems, subjected to singlepulse sine inputs, which uncover the existence of a fractal-type behaviour. This previously unsuspected trait of multi-block systems is reminiscent of the chaotic behaviour exhibited by a classical double pendulum and suggests that the risk of overturning can only be evaluated on a probabilistic sense.

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Rocking and Sliding of Unanchored Bodies Subjected to Seismic Load According to Conventional and Nuclear Rules

Cited by 5 publications

References 17 publications

Semi-active control of the rocking motion of monolithic art objects

Semi-active control of the rocking motion of monolithic art objects

Comparison of semi-active control strategies for rocking objects under pulse and harmonic excitations

Fractal-like overturning maps for stacked rocking blocks with numerical and experimental validation

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