ABSTRACT
Model. These two series of theories could analyze the behavior of RC members under combined actions fairly well by the help of finite-element method.
Huang & Liu (2007) proposed a theoretical model for RC box-section members under combined actions. Wang et al. (2014) proposed a theoretical model for RC rectangular members under combined actions. These two models try to have a clear theoretical basis and be convenient for application. In this paper, we attempt to determine the relationship between the external force and the twist failure surface. Then, a model is established on the basis of the ultimate equilibrium of twist failure surface.
