Real and fictitious elastic axes of multi-storey buildings: applications

Makarios, Triantafyllos K.; Anastassiadis, K.

doi:10.1002/(sici)1099-1794(199803)7:1<57::aid-tal96>3.0.co;2-0

Cited by 47 publications

(14 citation statements)

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“…The analyzed building is not strictly regularly asymmetric and does not have an elastic axis [21,33]. Therefore, in the paper, the optimum torsion axis [33,34] is assumed as reference axis to evaluate the stiffness eccentricities. This axis is defined as the vertical line that joins the points of the floors where the equivalent seismic forces must be applied in order to minimize the sum of the squares of Figure 18.…”

Section: Definition Of E R and ω θmentioning

confidence: 99%

“…the deck rotations. The optimum torsion axis can be determined either approximately as the vertical axis passing through the center of twist of the deck at a level equal to 0.80 H [33,34], or rigorously by the following equations derived in [35] x…”

Section: Definition Of E R and ω θmentioning

confidence: 99%

“…The ratios Ω θx and Ω θy are determined as the ratios of the radii of gyration of the stiffness r kx and r ky to r m . The radii of gyration of the stiffness r kx and r ky are calculated as suggested in [34]…”

Section: Definition Of E R and ω θmentioning

confidence: 99%

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Corrective eccentricities for assessment by the nonlinear static method of 3D structures subjected to bidirectional ground motions

Bosco

Ghersi

Marino

2012

Earthq Engng Struct Dyn

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SUMMARY Nonlinear static methods are reliable in the evaluation of the seismic response of planar structural schemes, but they are not very effective in the assessment of three‐dimensional building structures. The authors of this paper have recently proposed a nonlinear static approach for asymmetric structures, which is an improvement on that stipulated by seismic codes. This method is based on the observation that the distribution of the maximum dynamic displacements of the deck can be enveloped by two pushover analyses performed by applying the lateral force with two eccentricities with respect to the center of mass of the deck. These eccentricities, named “corrective eccentricities”, are defined so that the two corresponding pushover analyses provide displacements that are equal to those evaluated by nonlinear dynamic analysis at the two sides of the deck. In this paper, the corrective eccentricities are determined for a wide set of single‐story systems. The equations for their analytical evaluation are determined and their reliability is demonstrated. Finally, the analysis of a multi‐story structure is conducted to show how the method can be applied to real buildings. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Definition Of E R and ω θmentioning

confidence: 99%

Section: Definition Of E R and ω θmentioning

confidence: 99%

See 1 more Smart Citation

Corrective eccentricities for assessment by the nonlinear static method of 3D structures subjected to bidirectional ground motions

Bosco

Ghersi

Marino

2012

Earthq Engng Struct Dyn

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“…However, apart from the proportionate structures, these points are load-dependent and their space distribution is very irregular, even in uniform structures composed of different types of bents. More recently, Makarios and Anastassiadis (1998a, 1998b) introduced the “axis of optimum torsion” as a reference axis with promising results (Makarios, 2005, 2008; Makarios et al, 2006). This axis can be determined by means of an indirect static analysis by applying a set of floor torques equal in magnitude to the lateral forces at the same floors.…”

Section: Introductionmentioning

confidence: 99%

An approach for minimum rotational response of medium-rise asymmetric structures under seismic excitations

Georgoussis

2016

Advances in Structural Engineering

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Studied in this article is the elastic and inelastic rotational behavior of asymmetric multi-story buildings under unidirectional and bidirectional excitations in relation to the location of the modal center of rigidity. The concept of this point in mono-symmetric uniform buildings has been outlined by the author in earlier papers, and its significance lies on the property that when its location is within a close distance from the mass axis the torsional response is mitigated. At present, a generalized definition of this point is given for buildings with double eccentricity, using (1) the approach of the continuum medium and (2) the stiffness matrix methodology. To determine the location of modal center of rigidity in practical terms, a few modal quantities are required (element frequencies and effective modal masses), which may be easily obtained by commercial engineering software. To verify the aforesaid property of modal center of rigidity under unidirectional and bidirectional excitations, the rotational response of 10-story wall-frame structures is examined under the ground motions of Erzincan 1992 and Kobe 1995.

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“…Rakesh, 1998; Makarios and Anastassiadis, 1998b) that a rational determination of an axis of the generalized reference centres, representative of the plan asymmetry of the whole building, is very difficult. This implies that in real, common buildings, even when mass distributions fulfil the properties of regularly asymmetric systems, the equivalent static method proposed by codes generally cannot be used if procedures devoted to the definition of the reference axis location are not clearly stated.…”

Section: Introductionmentioning

confidence: 99%

Exact evaluation of the location of the optimum torsion axis

Marino

Rossi

2004

Structural Design Tall Build

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The paper addresses the issue of the evaluation of a reference axis which in multistorey buildings can play the same role as the elastic centre in one-storey schemes. In this regard the authors propose an improvement to the procedure previously suggested by Makarios and Anastassiadis for the evaluation of the position of the optimum torsion axis. The above-mentioned researchers based their evaluation on a parametric analysis of asymmetric frame-wall systems and thus defined the location of the optimum torsion axis only approximately. The authors, instead, face the problem from an analytical point of view and propose mathematical expressions that rigorously define the position of the same axis. Some examples are finally reported aiming at comparing the two approaches and highlighting the improvements brought by the rigorous approach to the approximate determination of the location of the optimum torsion axis.Given an orthogonal reference system OXYZ, having X and Y axes parallel to the principal axes of the resisting elements, let the degrees of freedom of the system be defined by the deck rotations q z and LOCATION OF THE OPTIMUM TORSION AXIS

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Real and fictitious elastic axes of multi-storey buildings: applications

Cited by 47 publications

References 1 publication

Corrective eccentricities for assessment by the nonlinear static method of 3D structures subjected to bidirectional ground motions

Corrective eccentricities for assessment by the nonlinear static method of 3D structures subjected to bidirectional ground motions

An approach for minimum rotational response of medium-rise asymmetric structures under seismic excitations

Exact evaluation of the location of the optimum torsion axis

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