Warping Torque of Symmetrical Non-Planar Open RC Sections
(2025) Concrete 2025 – Concrete Solutions for a Sustainable Future — Location: Adelaide, Australia (7.September.2025)
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- Authors
Hoult, Ryan 
- Abstract
- Many reinforced concrete (RC) building core walls have non-planar cross-sections, i.e. they are not rectangular. For example, U-shaped and H-shaped core wall cross-sections are popular in construction practice as, from an architectural perspective, these shapes can enclose elevator, stair shafts, and service systems, hence increasing the net lettable area. From the engineering standpoint, non-planar walls provide lateral stiffness in all horizontal directions. However, in the event of an earthquake, they will not only deform laterally but twist as well, to a minor or major extent. Building plan asymmetry is an important source of both simultaneous flexural and torsional demands to core walls during seismic ground motions. Current international building codes are not applicable for the design of non-planar, open sections, governed by warping torsion rather than circulatory torsion. The lack of information or guidance in building codes has resulted in few structures internationally being designed to account for warping stresses, which can be of a similar order of magnitude to the bending stresses and, therefore, of major significance. A simple procedure is herein presented to estimate the ultimate warping moment and torque of non-planar one-axis symmetrical RC sections, which only requires a sectional analysis and knowledge of the geometrical and mechanical properties. A case study building with a single RC U-shaped core is presented with example calculations to show how this procedure can be used to estimate the ultimate torque of the wall. A moment-torque interaction curve is used to claim that a reduction in the flexural bending moment is warranted for design purposes, particularly in the presence of moderate-to-large torsional actions.
- Affiliations
Citations
Hoult, R., & Saraiva Esteves Pacheco De Almeida, J. (2025). Warping Torque of Symmetrical Non-Planar Open RC Sections. Concrete 2025 – Concrete Solutions for a Sustainable Future, Adelaide, Australia. https://hdl.handle.net/2078.5/269710