Effects of torsion on the behavior of peripheral steel‐braced frame systems

Erduran, Emrah; Ryan, Keri L.

doi:10.1002/eqe.1032

Cited by 28 publications

(15 citation statements)

References 25 publications

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“…In general, higher mode effects decrease both in elevation and in plan, with increasing ground motion intensity. Some exceptions, representing extremely torsionally stiff structures, are discussed in De Stefano and Pintucchi (2010); Erduran and Ryan (2010). So, it is difficult to develop a relatively simple approach which would be able to simulate the structural response over the whole range of ground motion intensities that a structure may experience.…”

Section: Background Of the Extended Nmethods And Its Basic Assumptionsmentioning

confidence: 98%

The extended N2 method considering higher mode effects in both plan and elevation

Kreslin

Fajfar

2011

Bull Earthquake Eng

157

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The extended N2 method has been developed, which takes into account higher mode effects both in plan and in elevation. The extension is based on the assumption that the structure remains in the elastic range when vibrating in higher modes. The seismic demand in terms of displacements and storey drift can be obtained by combining the results of basic pushover analysis and those of standard elastic modal analysis. In the paper, the proposed procedure was summarized and applied to a test example which represents an actual 8-storey reinforced concrete building. The results obtained by the extended N2 method were compared with the results of nonlinear response history analysis and basic N2 analysis without the consideration of higher modes. The extended N2 method was able to provide fair, conservative estimates of response in the case of the test example. In comparison to the basic N2 method, the prediction of seismic demand was greatly improved in the upper part of the building and at the flexible edges.

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Section: Background Of the Extended Nmethods And Its Basic Assumptionsmentioning

confidence: 98%

The extended N2 method considering higher mode effects in both plan and elevation

Kreslin

Fajfar

2011

Bull Earthquake Eng

157

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“…This kind of buildings constitutes the common case in real life so it is urgent to implement updating formulations in these procedures turning the structural response as realistic as possible. Some efforts have been made to take this generation of NSPs to a higher performance level (Chopra and Goel 2004;Fajfar et al 2005;Bento et al 2010;Stefano and Pintucchi 2010;Erduran and Ryan 2010). The Eurocode8-1 (4.3.3.4.2.7 Procedure for the estimation of the torsional effects) includes some guidelines for the determination of torsional effects based on elastic analysis (e.g.…”

Section: Introductionmentioning

confidence: 99%

Assessing the seismic response of existing RC buildings using the extended N2 method

Bhatt

Bento

2011

Bull Earthquake Eng

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Extensive studies have confirmed the good performance of the N2 method, recommended by Eurocode8, when performing pushover analyses in regular structures. However, this procedure shows lack of accuracy in predicting the torsional motion of planasymmetric buildings. In order to overcome this problem, Peter Fajfar and his team have proposed an extension of the method based on a combination of a pushover analysis and of an elastic response spectrum analysis. Since definitive answers about this topic have not yet been reached, this paper intends to proceed the study applying the extended N2 method to real existing RC buildings. Three real plan-asymmetric buildings with three, five and eight storeys were assessed. The results obtained with the extended N2 method were compared with the ones evaluated by means of the original N2 and with the nonlinear dynamic analysis through the use of semi-artificial ground motions. The analyses were performed for different seismic intensities in order to evaluate the torsional response of the building through different stages of structural inelasticity. The results obtained show that the extended N2 method generally reproduces in a very good fashion the real torsional behavior of the analyzed buildings. The conclusions herein outlined, added to the ones already published by the aforementioned authors, seem to confirm that the extended N2 method can be introduced in the next version of Eurocode8 as a nonlinear static procedure capable of accurately predicting the torsional response of plan-asymmetric buildings.Keywords Seismic assessment · 3D pushover analysis · Extended N2 method · Real plan-asymmetric buildings · Torsion

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“…Various studies have examined in detail the seismic drift demands in plan‐asymmetric structures, for example 9–11 , including the effects of degradation 12 and ground‐motion scaling 13 . However, a basic lack of agreement subsists in relation to the definition of adequate parameters of the system and its response 14 .…”

Section: Introductionmentioning

confidence: 99%

“…The seismic response of eccentric buildings is particularly sensitive to the features of the ground motion 19 and issues concerning the selection, scaling and application of ground‐motion records deserve careful consideration 20 . Although real seismic motion involves three translational and three rotational components, and robust procedures for the estimation of rotational motions have now become available, 21 it is still customary to neglect the effects of the rotational ground‐motion components 8 and rely on the application of orthogonal pairs of acceleration series 11,22,23 . In this regard, several researchers have studied the influence of the record‐pair orientation on the estimation of structural responses from non‐linear response history analysis.…”

Section: Introductionmentioning

confidence: 99%

Strong‐motion duration and response scaling of yielding and degrading eccentric structures

Mariotti

2020

Earthq Engng Struct Dyn

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Plan irregular structures, whose complex response represents a generalisation of the simpler de-coupled motion ascribed to symmetric buildings, make up a large proportion of the failures during major earthquakes. This paper examines the seismic response scaling of degrading and no-degrading eccentric structures subjected to bidirectional earthquake action and its relationship with the duration of the ground motion by means of dimensional and orientational analyses. Structures with reflectionally symmetric stiffness distribution and mass eccentricity subjected to orthogonal pairs of ideal pulses are considered as the fundamental case. The application of Vaschy-Buckingham's Π-theorem reduces the number of variables governing the peak orthogonal displacements leading to the emergence of remarkable order in the structural response. If orientationally consistent dimensionless parameters are selected, the response becomes self-similar. By contrast, when degradation is introduced, peak inelastic displacements are dramatically affected and the self-similarity in the response is lost immediately after the onset of inelastic deformations. Conversely, if the uniform duration, instead of the period, of the strong motion is adopted as a timescale, a practically self-similar response is observed. This offers unequivocal proof of the fundamental role played by the ground-motion duration in defining the peak displacement response of degrading structures even at small inelastic demands, although its importance increases with increasing deformation levels. Finally, the existence of complete similarities, or similarities of the first kind, are explored and the practical implications of these findings are briefly outlined in the context of real pulse-like ground motions with varying degrees of coherency.

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Effects of torsion on the behavior of peripheral steel‐braced frame systems

Cited by 28 publications

References 25 publications

The extended N2 method considering higher mode effects in both plan and elevation

The extended N2 method considering higher mode effects in both plan and elevation

Assessing the seismic response of existing RC buildings using the extended N2 method

Strong‐motion duration and response scaling of yielding and degrading eccentric structures

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