Tasarım Eksantrikliği İçin Alternatif Bir Öneri

Akyürek, Osman

doi:10.2339/politeknik.979143

“…The definition and formula given for an alternative design eccentricity including frequency ratio, , here was proposed by the first author in his study 28 . For better understanding and clarification of the model, it is stated here again.…”

Section: Proposed Design Eccentricitymentioning

confidence: 99%

“…The current code provision, ASCE 7-22, might be insufficient to represent the effects of torsion 26,27 . Therefore, an alternative design eccentricity formula was proposed 28 , which includes the frequency ratio (torsional frequency/translation frequency for each direction) and an effective radius of rotation to reconsider the torsional irregularity. In this study, the extended performance evaluation of the proposed design eccentricity was made.…”

Section: Introductionmentioning

confidence: 99%

An Alternative Recommendation for Design Eccentricity by Consideration of Uncoupled Frequency Ratio

Akyürek,

Ulutaş

2024

Preprint

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Civil structures are prone to dynamic loadings such as strong winds or ground excitations where torsion becomes an ongoing issue. This arises from a lack of coincidence of the center of mass (CM) and rigidity (CR), known as eccentricity. Seismic design codes often introduce two types of eccentricity: inherent (geometric) and accidental. To account for structural or ground motion uncertainties, an assumption-based solution is provided by many code provisions, which considers the accidental eccentricity as a percentage (5% or 10%) of the building length perpendicular to the direction of exposed ground motion. In this study, as an alternative way to the code design parameters, a new design eccentricity formula that considers the frequency ratio (torsional frequency/translation frequency) and an effective radius of gyration to account for torsional irregularity is considered. For the extended validation of the proposed method, eighteen model buildings with six different floor plans were chosen, representing low, medium-height, and high-rise buildings. Each floor plan had model buildings with three, seven, and twelve stories. The buildings were subjected to selected bidirectional earthquake ground motions and had time history analyses performed. The results of the proposed method were compared to code provision methods, obtained using equivalent lateral force procedures, and also to those obtained utilizing the time history analysis results. It was shown that the proposed method was more effective in estimating the impact of torsional eccentricity and provided a better understanding of its impact on structural dynamic characteristics.

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An alternative recommendation for design eccentricity by consideration of uncoupled frequency ratio

Akyürek,

Ulutaş

2024

Sci Rep

0

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Civil structures are prone to dynamic loadings such as strong winds or ground excitations where torsion becomes an ongoing issue. This arises from a lack of coincidence of the center of mass (CM) and rigidity (CR), known as eccentricity. Seismic design codes often introduce two types of eccentricity: inherent (geometric) and accidental. To account for structural or ground motion uncertainties, an assumption-based solution is provided by many code provisions, which considers the accidental eccentricity as a percentage (5% or 10%) of the building length perpendicular to the direction of exposed ground motion. In this study, as an alternative way to the code design parameters, a new design eccentricity formula that considers the frequency ratio (torsional frequency/translation frequency) and an effective radius of gyration to account for torsional irregularity is considered. For the extended validation of the proposed method, eighteen model buildings with six different floor plans were chosen, representing low, medium-height, and high-rise buildings. Each floor plan had model buildings with three, seven, and twelve stories. The buildings were subjected to selected bidirectional earthquake ground motions and had time history analyses performed. The results of the proposed method were compared to code provision methods, obtained using equivalent lateral force procedures, and also to those obtained utilizing the time history analysis results. It was shown that the proposed method was more effective in estimating the impact of torsional eccentricity and provided a better understanding of its impact on structural dynamic characteristics.

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An Approach for Modelling Accidental Eccentricity Effects in Symmetrical Frame Buildings Exhibiting Semi-Rigid Diaphragm Behavior

Sürmeli

2024

Sakarya University Journal of Science

0

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The accidental eccentricity effect is specified, in earthquake codes, to account for the possible uncertainties in the mass and stiffness distribution of the structural system and the effect of the torsional component of the earthquake ground motion on the building. Türkiye Building Earthquake Code (TBEC-2018) considers the additional eccentricity effect only for the cases where rigid diaphragm behavior is provided in the slabs. However, in buildings with A2 and A3 irregularities or flexible diaphragms including insufficient strength and stiffness, the in-plane deformations and stresses on diaphragms may change the behavior of buildings under earthquake loads. In this study, a practical approach to be used in the equivalent earthquake load method was proposed to apply the accidental eccentricity effect on symmetrical frame buildings with semi-rigid diaphragms. The approach is based on distributing the total accidental torsion to the nodes as fictitious forces. Two numerical examples were presented. The first is a single-story precast industrial-type RC building, where the calculation steps of the procedure explained in detail. The building was modeled with both semi-rigid and rigid diaphragm assumptions, and a comparison of two modeling assumptions under accidental torsion was presented. Torsional irregularity factors obtained from building modeled by semi-rigid diaphragm assumption provided greater values with respect to those modeled by rigid diaphragm. This shows the significance of considering accidental eccentricity for semi-rigid diaphragms. The second numerical example, which is a RC concrete building, was used to validate the proposed methodology via finite element model (FEM) built-in algorithm. The obtained displacement demands by using the proposed methodology were very close to FEM results as a reference for the real solution. It is concluded from this study that the proposed methodology is reliable and can be used for modeling accidental eccentricity effects on symmetrical-plan buildings with semi-rigid diaphragms.

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Tasarım Eksantrikliği İçin Alternatif Bir Öneri

Cited by 3 publications

References 20 publications

An Alternative Recommendation for Design Eccentricity by Consideration of Uncoupled Frequency Ratio

An Alternative Recommendation for Design Eccentricity by Consideration of Uncoupled Frequency Ratio

An alternative recommendation for design eccentricity by consideration of uncoupled frequency ratio

An Approach for Modelling Accidental Eccentricity Effects in Symmetrical Frame Buildings Exhibiting Semi-Rigid Diaphragm Behavior

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