Flexure–Torsion Response of Compressed Open Reinforced-Concrete Cores: Experimental Strain Gradients, Numerical Methods, and Interaction Diagrams
Publication: Journal of Structural Engineering
Volume 150, Issue 9
Abstract
Together with axial and flexural actions, modern-designed reinforced-concrete walls can also be subjected to torsion during rare loading events, such as large-magnitude earthquakes or strong winds. For certain widely used nonplanar open cross-section geometries, this torque is resisted primarily through warping. In some cases, the longitudinal stresses caused by torsional warping can be of the same order of magnitude as those caused by flexure, which postulates a reduction of the in-plane bending moment capacity of the section. This study explores the reduction of bending moment capacity of open reinforced-concrete U-shaped core walls due to the simultaneous application of flexural, axial, and torsional loading. Initial investigations focused on strain gradients through the wall segments of reinforced-concrete U-shaped walls. Using a refined data set from a recent experimental campaign, the commonly assumed linear strain gradient used in the design of reinforced-concrete walls is challenged. Numerical methods that intrinsically rely on the observed strain gradients are then employed to compute, for a range of torque-to-bending-moment ratios, the ultimate bending moment and torque capacities from combined loading scenarios. The numerical results corroborate existing experimental results, indicating a significant reduction (almost half) in ultimate bending moment capacity when a torque equal to approximately 20% of imposed bending is applied. Interaction diagrams between the ultimate torque and bending moment show that it is possible to derive a simple relationship between the two for the purposes of structural design. These results can help formulate guidelines for future international building codes, which in their current form cannot account for the design of open sections governed by warping torsion.
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Data Availability Statement
Some or all data, models, or code generated or used during the study are available in the Dataverse repository online (https://doi.org/10.14428/DVN/FDJ4EU) in accordance with funder data retention policies.
Acknowledgments
This work was supported by the Fonds de la Recherche Scientifique–FNRS under Grant No. F.4501.21.
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© 2024 American Society of Civil Engineers.
History
Received: Aug 26, 2023
Accepted: Mar 14, 2024
Published online: Jul 1, 2024
Published in print: Sep 1, 2024
Discussion open until: Dec 1, 2024
ASCE Technical Topics:
- Bending (structural)
- Concrete
- Continuum mechanics
- Core walls
- Deformation (mechanics)
- Dynamics (solid mechanics)
- Engineering fundamentals
- Engineering materials (by type)
- Engineering mechanics
- Forces (type)
- Materials engineering
- Methodology (by type)
- Moment (mechanics)
- Numerical methods
- Reinforced concrete
- Solid mechanics
- Statics (mechanics)
- Structural dynamics
- Structural engineering
- Structural mechanics
- Structural members
- Structural systems
- Torsion
- Walls
- Warpage
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