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Nonplanar reinforced concrete (RC) core walls form the backbone of millions of mid- and high-rise buildings, resisting both gravity and lateral loads from wind and earthquakes. The latter inevitably induces torsional demands, even in the case of full plan-wise symmetric structures, which add to bending, shear, and axial deformations. Unfortunately, current international building codes are not applicable for the design of nonplanar sections governed by warping torsion rather than circulatory torsion. This lack of information and guidance in building codes has resulted in a very limited number of structures being designed to account for warping stresses, even though the latter can be of a similar order of magnitude to bending stresses and, therefore, of major significance. A simple procedure is herein presented to estimate the ultimate warping moment and ultimate torque of nonplanar RC sections based on "warping-equivalent" ultimate bending moments from sectional analysis. A circular and bilinear bending moment-torque interaction relationship is proposed and compared to the existing, albeit limited, experimental and numerical results available in the literature. [ABSTRACT FROM AUTHOR]

This research investigates the equivalent plastic hinge length of reinforced concrete C-shaped walls with reinforcement detailing typically found in low-to-moderate seismic regions. Reinforced concrete walls in these regions commonly have low amounts of longitudinal reinforcement and unconfined boundary regions, which have been shown to perform poorly in recent earthquake events. A series of state-of-the-art finite element analyses are undertaken to find the longitudinal strain distributions of low-rise, mid-rise, and high-rise C-shaped walls. The results of the equivalent plastic hinge lengths from the numerical investigation are shown to compare poorly to the predictions from some of the equations that currently exist in the literature. Subsequently, expressions are derived for the equivalent plastic hinge length for these types of walls and for the different modes of bending. The expressions derived from this research intend to improve the displacement capacity for these types of walls when using plastic hinge analyses. [ABSTRACT FROM AUTHOR]