Intensity measures as interfacing variables versus response proxies: The case of rigid rocking blocks

Lachanas, Christos G.; Vamvatsikos, Dimitrios; Dimitrakopoulos, Elias G.

doi:10.1002/eqe.3838

Cited by 9 publications

(7 citation statements)

References 68 publications

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“…In this example, the values for a and b are −0.36 and 0.73, respectively; and the values for c and d are 0.46 and 0.67, respectively. This observation aligns with findings from other types of rocking structures [61][62][63], indicating a sensitivity to major velocity pulses. Consequently, this result underscores the importance of considering the velocity spectrum characteristics of the construction site when defining input motion in the design of pole-type structures with restrained rocking.…”

Section: Discussionsupporting

confidence: 90%

Seismic Isolation of Fragile Pole-Type Structures by Rocking with Base Restraints

Li,

Hu,

et al. 2024

Buildings

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Pole-type structures are vulnerable to earthquake events due to their slender shapes, particularly porcelain cylindrical equipment in electrical substations, which has inherent fragility and low strength in its materials. Traditional base isolation designs configure the bottom of the pole-type equipment as hinges with restraints. It fully relies on the restrainers to re-center the pole-type equipment, posing a risk of tilting and functionality failure after earthquakes. This study proposes a solution to this challenge by introducing a restrained rocking mechanism at the base of the structure. The design leverages the self-centering nature of rocking motion and uses restrainers to control the amplitude of rotation. Hence, it can effectively avoid tilting of the pole-type structures after earthquakes. Experimental investigations conducted on a 1:1 full-scale specimen revealed that the proposed restrained rocking design can achieve a reduction in seismic internal forces of over 50% while maintaining equipment in an upright position. Furthermore, an analytical model for the proposed isolation system of pole structures was developed and validated through comparison with experimental results. This paper introduces a novel solution for seismic isolation of pole-type structures through restrained rocking, specifically addressing the research gap regarding a reliable self-centering mechanism under seismic excitation. This advancement significantly enhances the seismic resilience of fragile pole-type structures and provides practical design methodologies for the seismic isolation of slender structures.

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Section: Discussionsupporting

confidence: 90%

Seismic Isolation of Fragile Pole-Type Structures by Rocking with Base Restraints

Li,

Hu,

et al. 2024

Buildings

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“…Later, Petrone et al 21 . and Lachanas et al 22 . verified the importance of PGV and PGA to the overturning of slender and stocky rocking structures, respectively.…”

Section: Introductionmentioning

confidence: 97%

“…16,17 Psycharis et al 18 illustrated the importance of peak ground velocity (PGV) over peak ground acceleration (PGA) to rocking response; similar results were later found in Sieber et al 19 Dimitrakopoulos and Paraskeva 20 highlighted the contribution of PGV and a combination of PGA with a frequency characteristic (PGA/PGV) to rocking amplitude. Later, Petrone et al 21 and Lachanas et al 22 verified the importance of PGV and PGA to the overturning of slender and stocky rocking structures, respectively. Liu et al 23 showed the influence of the combined consideration of peak and frequency characteristics of the ground excitation on rocking response.…”

Section: Introductionmentioning

confidence: 97%

A multi‐level approach to predict the seismic response of rigid rocking structures using artificial neural networks

Banimahd,

Giouvanidis,

Karimzadeh

et al. 2024

Earthq Engng Struct Dyn

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This paper explores the use of Artificial Neural Networks (ANN) for the rocking problem. The paper adopts rigid rocking blocks of different sizes and slenderness, which undergo rocking motion without sliding and bouncing when subjected to recorded earthquakes. This research focuses on the cases where the blocks overturn or safely return to their initial (rest) position at the end of the ground shaking. An ANN model is trained to efficiently categorise the response into overturning or safe rocking using the structural parameters, ground motion characteristics, and the coefficient of restitution as input. The results show the substantial contribution of velocity and frequency characteristics of the ground motion to overturning. In addition, ANN is used to predict the response amplitude and identify the most critical input variables that govern safe rocking. The analysis reveals that rocking amplitude is governed by a combination of duration, frequency, and intensity characteristics of the ground excitation. Interestingly, the maximum incremental velocity (MIV), a novel intensity measure for the rocking literature, shows a substantial correlation with the rocking amplitude. In this context, this paper proposes closed‐form expressions using the most influential input variables to provide a quick, yet adequately accurate, response prediction. Finally, this study pays special attention to the contribution of the coefficient of restitution, which, in general, is less critical to the peak safe rocking response, while it becomes more important to the overturning response.

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“…Recently, statistical methods based on "rocking spectra" or on the Incremental Dynamic Analysis (IDA) [57][58][59][60] were proposed for the design and analysis of rocking structures. Nevertheless, performing nonlinear time-history analyses remains the most widespread approach for the prediction of the rocking response.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Modeling of the Shake-Table Response of a Bridge-Like Model Comprising Rocking Columns

Katsamakas,

Vassiliou

2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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This paper presents a three-dimensional finite element model to predict the shake-table response of a rocking bridge-like specimen. The numerical model is statistically validated against experimental results, which involved testing of the system under 169 three-directional ground motions. The model comprises four cylindrical rocking columns capped with a concrete slab. The columns are connected to the slab with flexible tendons and they are allowed to uplift and wobble. The use of flexible tendons allows for large displacements of the system and negative post-uplift stiffness. This mechanism acts as a form of seismic isolation, limiting the accelerations transmitted to the superstructure. The rocking columns, the slab and the shake table are modeled using elastic elements. The tangential behavior of the contact surfaces is modeled with Coulomb friction, which is the main energy dissipation mechanism. The tendons are modeled with equivalent elastic springs. The numerical analysis accounts for the geometric non-linearity of the response. Rocking motion is sensitive to the parameters that define it and experimental tests are often non-repeatable. Hence, this study employs a statistical approach to validate the proposed numerical model. The cumulative distribution function (CDF) of the response quantity of interest (e.g., maximum displacement at the center of the slab) is employed, instead of comparing the numerical and experimental results one-by-one for each test (deterministic comparison). The deterministic validation of the model shows a moderate correlation of the experimental and the numerical results. However, the model can accurately predict the statistical response for both parameters of interest (i.e., maximum displacement and maximum rotation) of the system under 169 ground motion excitations.

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Intensity measures as interfacing variables versus response proxies: The case of rigid rocking blocks

Cited by 9 publications

References 68 publications

Seismic Isolation of Fragile Pole-Type Structures by Rocking with Base Restraints

Seismic Isolation of Fragile Pole-Type Structures by Rocking with Base Restraints

A multi‐level approach to predict the seismic response of rigid rocking structures using artificial neural networks

Finite Element Modeling of the Shake-Table Response of a Bridge-Like Model Comprising Rocking Columns

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