Decay of Torsional Stiffness in RC U-Shaped Walls
Publication: Journal of Structural Engineering
Volume 146, Issue 9
Abstract
Reinforced concrete (RC) U-shaped walls are a popular construction choice, commonly used to resist the lateral loads from wind and earthquakes. In many buildings, the center of stiffness of a floor is eccentric from the center of mass and the building will therefore undergo some twist. Often, U-shaped walls contribute significantly to the torsional stiffness of the building and the analysis of the structure therefore requires an estimate of the torsional stiffness. This research investigates the dependency of the torsional stiffness of U-shaped walls on the translational displacement demands using experimental evidence and advanced numerical models. The experimental results show that the torsional stiffness decreases with increasing translational displacement. Furthermore, the numerical and experimental results indicate that the torsional stiffness degrades at a similar rate as the translational stiffness of the walls. The rotational stiffness of the wall is smaller when it is centered than when it is subjected to a translation. This effect is attributed to the longitudinal stresses throughout the cross section that are already present due to the imposed flexural displacement. In particular, the compression zone resulting from the translational displacement imposed on the wall stiffens the wall with regard to the twisting. As a result, the effective torsional stiffness increases with increasing axial load ratio. Current codes do not provide reduction factors for the torsional stiffness, but the results show that the reduction factors for the shear stiffness can serve as estimate, albeit they do not capture the dependence on the axial load ratio.
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Data Availability Statement
The experimental and numerical dataset from the numerical research investigation undertaken in this paper can be downloaded from the publicly accessible platform Zenodo, DOI: 10.5281/zenodo.2580024. The structure of the data folders is described in the report “Data_organization_Hoult_Beyer_2019.pdf,” also available for download. The following data is provided: (1) experimental dataset for specimens TUA and TUB, which includes the applied twists; (2) VecTor3 files; and (3) MATLAB files (for reproducing graphs and figures). This readily available dataset allows transparency of the data and files that were used to compile the results in this paper. Furthermore, the dataset also allows replicability studies to be conducted with some ease. The dataset also allows greater opportunities for sharing and reusing the research data produced from this investigation, which may help future studies that focus on similar topics.
Acknowledgments
The authors would like to acknowledge the support of the Swiss Government Excellence Postdoctoral Scholarship for the year 2018/2019.
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Published In
Journal of Structural Engineering
Volume 146 • Issue 9 • September 2020
Copyright
©2020 American Society of Civil Engineers.
History
Received: Jul 9, 2019
Accepted: Mar 2, 2020
Published online: Jun 23, 2020
Published in print: Sep 1, 2020
Discussion open until: Nov 23, 2020
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