Modeling of Rocking Elastic Flexible Bodies under Static Loading Considering the Nonlinear Stress Distribution at Their Base

Avgenakis, Evangelos; Psycharis, Ioannis N.

doi:10.1061/(asce)st.1943-541x.0001783

Cited by 17 publications

(23 citation statements)

References 23 publications

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“…The basic steps of the elastic material formulation found in [18] are summarized here, since this also serves as the basis of the material nonlinearity formulation.…”

Section: Elastic Materials Formulationmentioning

confidence: 99%

“…and the polynomial constant term V and R (for the normal stress contribution) and V ⌧ 0 , V ⌧ ⌫ , R ⌧ 0 , R ⌧ ⌫ (for the shear stress contribution) vectors given in [18].…”

Section: Elastic Materials Formulationmentioning

confidence: 99%

“…A new macroelement formulation has been recently proposed by the authors ( [18]), which is able to take into account both the deformability of the rocking member along its height, as well as the stress nonlinearity near the contact area, which is crucial in many applications, especially regarding members with constrained rocking motion. The material in this macroelement was assumed to be elastic.…”

Section: Introductionmentioning

confidence: 99%

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A New Computational Approach for the Rocking Response of Deformable Bodies Considering Material Nonlinearity

Avgenakis¹,

Psycharis²

2017

Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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Abstract. An increasing interest in the use of rocking members in earthquake resistant structural systems has been observed in recent years. The benefits of such members include the limitation of the damage, re-centering capabilities and reduction of seismic forces transmitted to the rest of the structure due to a yield-like response.Despite the importance of such members, few models able to describe the response of flexible rocking members in structural systems realistically can be found in literature, since most of the research focuses on the response of rigid bodies or ignores the stress nonlinearity near the contact area, which is considered crucial to the accurate determination of the rocking response of deformable rocking bodies. A new macro-element formulation for elastic rocking members has been proposed by the authors in previous papers which is able to take into account this stress nonlinearity, producing results which are very close to the ones produced by conventional finite element programs.Rocking members in structural systems are expected to behave inelastically for large seismic excitations. In this paper, the macroelement presented previously by the authors, which considered the element material to be elastic, is extended to also take material nonlinearity into account. The effect of the nonlinear stress distribution across the rocking interface on the member displacements is determined and approximate formulas for their determination are included in the macro-element formulation. The results produced by the macro-element with the inelastic material are finally compared to the ones of conventional finite element codes, showing very good agreement between the results of the two methods.

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“…The basic steps of the elastic material formulation found in [18] are summarized here, since this also serves as the basis of the material nonlinearity formulation.…”

Section: Elastic Materials Formulationmentioning

confidence: 99%

“…and the polynomial constant term V and R (for the normal stress contribution) and V ⌧ 0 , V ⌧ ⌫ , R ⌧ 0 , R ⌧ ⌫ (for the shear stress contribution) vectors given in [18].…”

Section: Elastic Materials Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A New Computational Approach for the Rocking Response of Deformable Bodies Considering Material Nonlinearity

Avgenakis¹,

Psycharis²

2017

Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

Self Cite

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“…2 Since Housner's publication, research on rocking structures has flourished ( 3-6 and references therein). It has been shown that the aforementioned properties also hold for flexible [7][8][9][10][11][12][13][14][15][16] and 3D structures. [17][18][19][20][21][22][23] Assemblies of planar rocking structures have also been studied, and it has been proven that rocking frames are more stable than their columns alone, even though their center of gravity lies higher.…”

Section: Introductionmentioning

confidence: 99%

Seismic response of a wobbling 3D frame

Vassiliou

2017

Earthq Engng Struct Dyn

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Summary This paper investigates the 3D response of a slab supported by wobbling columns. The columns are not allowed neither to slide nor to roll out of their initial position. An analytical model is proposed, the equations of motion are derived, and they are solved numerically. The paper concludes that the addition of the slab makes the columns more stable. In fact, the system is almost equivalent to the response of a solitary column with the same aspect ratio yet larger size. However, it is also shown that the system is less stable than its planar counterpart and that planar analysis can only qualitatively describe the behavior of 3D structures. A case study shows that the concept could be used as a seismic isolation technique for bridges. However, more research need to be performed on defining proper intensity measures for uplifting structures, as it is shown that there is large record‐to‐record variability, even when intensity measures developed for rocking structures are used.

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“…No sliding is allowed for this purpose. As shown in Figure 4C, the piers are modeled with solid elements (instead of beam elements) in order to simulate the rocking interface, where plane sections are not expected to remain plane (Avgenakis and Psycharis, 2017). The pier ends of the actual structure would be protected with steel jackets and no concrete spalling would be expected as it was observed in experimental testing (Thonstad et al, 2016;Mashal and Palermo, 2017).…”

Section: Rocking Piers Modelmentioning

confidence: 99%

Comparative Assessment of Two Rocking Isolation Techniques for a Motorway Overpass Bridge

Agalianos

Psychari

Vassiliou

et al. 2017

Front. Built Environ.

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Rocking isolation of structures is evolving as an alternative design concept in earthquake engineering. The present paper investigates the seismic performance of an actual overpass bridge of the Attiki Odos motorway (Athens, Greece), employing two different concepts of rocking isolation: (a) rocking of the piers on the foundation (rocking piers); and (b) rocking of the pier and foundation assembly (rocking footings) on the soil. The examined bridge is an asymmetric 5-span system having a continuous deck and founded on surface foundations on a deep clay layer. The seismic performance of the two rocking-isolated bridges is comparatively assessed to the existing bridge, which is conventionally designed according to current seismic design codes. To that end, 3D numerical models of the bridge-foundation-abutment-soil system are developed, and both static pushover and non-linear dynamic time history analyses are performed. For the latter, an ensemble of 20 records (10 ground motions of 2 perpendicular components each) that exceed the design level are selected. The conventional system collapses in 5/10 of the (intentionally severe) examined seismic excitations. The rocking piers design alternative survives in 8/10 of the cases examined, with negligible residual deformations. The safety margins of the rocking footings design concept are even larger, as it survives in all cases examined. Both rocking isolation concepts are proven to offer increased levels of seismic resilience, reducing the probability of collapse and the degree of structural damage. Nevertheless, in the rocking piers design alternative high stress concentrations at the rotation pole (pier base) are developed, indicating the need for a special design of the pier ends. This is not the case for the rocking footings concept, which however is subject to increased residual settlements but no residual rotations.

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Modeling of Rocking Elastic Flexible Bodies under Static Loading Considering the Nonlinear Stress Distribution at Their Base

Cited by 17 publications

References 23 publications

A New Computational Approach for the Rocking Response of Deformable Bodies Considering Material Nonlinearity

A New Computational Approach for the Rocking Response of Deformable Bodies Considering Material Nonlinearity

Seismic response of a wobbling 3D frame

Comparative Assessment of Two Rocking Isolation Techniques for a Motorway Overpass Bridge

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