Rigid‐plastic models for the seismic design and assessment of steel framed structures

Mariotti, C.; Elghazouli, A.Y.; Bento, Rita

doi:10.1002/eqe.920

Cited by 16 publications

(14 citation statements)

References 14 publications

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“…larger initial displacements leading to earlier hinge formation for ξ = 1 than 5%). However, the tendency of very stiff structures with negligible damping and significant strength degradation to undergo oscillations around zero drifts, as opposed to the marked unsymmetrical ratcheting response observed for the same structures for relatively mild values of additional energy dissipation , may contribute towards 5%‐damped structures experiencing consistently larger drifts and plastic damage levels. These phenomena are further manifested in the lower IMs at which the mean plasticity rises above zero at ξ = 5 than at 1% for both NF and FF records and in wider 95% CIs for the imperfect structure (Figures and ).…”

Section: Response‐history and Multiple Stripe Analysesmentioning

confidence: 99%

Seismic analysis of a tall metal wind turbine support tower with realistic geometric imperfections

Sadowski

Cámara

Mariotti

et al. 2016

Earthq Engng Struct Dyn

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analysis of a tall metal wind turbine support tower with realistic geometric imperfections. Earthquake Engineering and Structural Dynamics, 46(2), pp. 201-219. doi: 10.1002/eqe.2785 This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent AbstractThe global growth in wind energy suggests that wind farms will increasingly be deployed in seismically active regions, with large arrays of similarly-designed structures potentially at risk of simultaneous failure under a major earthquake. Wind turbine support towers are often constructed as thin-walled metal shell structures, wellknown for their imperfection sensitivity, and are susceptible to sudden buckling failure under compressive axial loading.This study presents a comprehensive analysis of the seismic response of a 1.5 MW wind turbine steel support tower modelled as a near-cylindrical shell structure with realistic axisymmetric weld depression imperfections. A selection of twenty representative earthquake ground motion records, ten 'near-fault' and ten 'far-field', was applied and the aggregate seismic response explored using lateral drifts and total plastic energy dissipation during the earthquake as structural demand parameters.The tower was found to exhibit high stiffness, though global collapse may occur soon after the elastic limit is exceeded through the development of a highly unstable plastic hinge under seismic excitations. Realistic imperfections were found to have a significant effect on the intensities of ground accelerations at which damage initiates and on the failure location, but only a small effect on the vibration properties and the response prior to damage. Including vertical accelerations similarly had a limited effect on the elastic response, but potentially shifts the location of the plastic hinge to a more slender and therefore weaker part of the tower. The aggregate response was found to be significantly more damaging under near-fault earthquakes with pulse-like effects and large vertical accelerations than far-field earthquakes without these aspects. KeywordsThin metal shell structure, imperfection sensitivity, seismic response, multiple stripe analysis, near-fault ground motions, vertical ground acceleration.

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Section: Response‐history and Multiple Stripe Analysesmentioning

confidence: 99%

Seismic analysis of a tall metal wind turbine support tower with realistic geometric imperfections

Sadowski

Cámara

Mariotti

et al. 2016

Earthq Engng Struct Dyn

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“…The 6-storey building was designed and modelled by Málaga-Chuquitaype et al [28] and has an initial period of T = 1.1 seconds and a mass of 1085350 kg while the two-storey frame has an initial period of T = 0.22 second (obtained from Eigenvalue analysis) and a mass of 43100 kg. The slenderness of the first-storey braces areλ = 1.1 for the 6-storey building andλ = 1.3 for the 2-storey frame.…”

Section: Case Studiesmentioning

confidence: 99%

“…The response to El Centro record with T m = 0.986 seconds is considered as an example. The record was scaled to have a P GA over acceleration at yield equal to 3, which corresponds to Root Mean Squared Accelerations of a RM S = 2.64g and a RM S = 0.93g for the 6-storey and 2-storey buildings, respectively [28].…”

Section: Case Studiesmentioning

confidence: 99%

Estimation of peak displacements in steel structures through dimensional analysis and the efficiency of alternative ground-motion time and length scales

Mariotti

2015

Engineering Structures

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This paper deals with the estimation of maximum displacements in single-degree-of-freedom (SDOF) systems simulating typical steel structures by means of dimensional analysis. Peak deformation demands in bilinear systems (representative of moment resisting frames) are considered as well as additional pinching models depicting partially-restrained (PR) and concentrically-braced (CB) frames subjected to a series of non-coherent acceleration records. Particular attention is given to the identification of efficient length and time scales in nonpulselike earthquake motions. The relative merits of incorporating the mean period of the ground-motion (T m ), predominant period (T p ), significant duration (t sig ) as well as peak ground acceleration (P GA), peak ground velocity (P GV ), root mean square acceleration (a RM S ), root mean square velocity (v RM S ) and Arias Intensity (I a ) within the dimensionless functional form are evaluated. When the normalized peak displacements of bilinear, PR and CB oscillators are presented as a function of the normalized yield displacement and dimensionless characteristic structural strengths (both total and at pinching intervals), a clear pattern emerges and the response becomes self-similar. This paper demonstrates that the use of the mean period (T m ) as a time scale produces consistently lower dispersion and bias in the estimations of maximum displacements in comparisons with other ground-motion time scales. Similarly, the root mean square acceleration (a RM S ) is found to be the most efficient amplitude-related parameter for the estimation of maximum displacements in bilinear and CB structures whereas the peak ground acceleration (P GA) is the most efficient ground-motion parameter for the prediction of peak deformations in PR systems. Finally, simple expressions for the assessment of displacement demands in steel structures based on the most-efficient dimensionless master curves are proposed and verified.

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“…Among them, rigid-plastic approximations, largely diffused in earthquake engineering, give rise to simplified procedures [5], although its implementation within conventional stiffness-based computer methods, the instantaneous jump of stiffness between zero and infinite. The model examined in this paper, together with those developed for rigid-plastic bending frames, overcomes this last limit [6,7]. In literature, in fact, constitutive models for rigid-plastic bending frames are diffused, differently from the shear constitutive ones.…”

Section: Introductionmentioning

confidence: 99%

Shear Plastic Oscillations of a Wind Turbine Tower

Monaco¹,

Tafuro²,

Calderoni³

et al. 2019

Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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The vulnerability of wind turbine towers is an actual theme, considered the recent diffusion of aeolian parks. In many cases collapses of wind towers after severe actions have been observed. The analysis of structures subjected to variable actions can be performed by means of several methods with different levels of accuracy. Nonlinear dynamics is generally considered the most reliable one. This paper presents a numerical procedure for the analysis of rigidplastic response of a wind turbine tower, considered a cantilever beam subjected to harmonic forcing motion of the base support. The failure is assumed depending on the formation shear hinges and the results are expressed in general terms for application to real cases. The proposed model is an evolution of the cantilever model with a single degree of freedom, since the plastic hinges can form in every section of the beam. For the solution of the problem, a numerical procedure has been developed that provides simple relationships between the strength of the structure and parameters useful for design purposes. The approach presents the advantages of rigid-plastic procedure and an efficient representation of the post-elastic behaviour of the structure, low computational competence and limited number of mechanical parameters are involved.

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Rigid‐plastic models for the seismic design and assessment of steel framed structures

Cited by 16 publications

References 14 publications

Seismic analysis of a tall metal wind turbine support tower with realistic geometric imperfections

Seismic analysis of a tall metal wind turbine support tower with realistic geometric imperfections

Estimation of peak displacements in steel structures through dimensional analysis and the efficiency of alternative ground-motion time and length scales

Shear Plastic Oscillations of a Wind Turbine Tower

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