Concrete component of the rotational ductility of reinforced concrete flexural members

Abstract

Reinforced concrete flexural members inherently rely on member ductility to ensure a safe design by allowing for: redistribution of applied stress resultants; quantification of drift for determining magnified moments; and for the absorption of seismic, blast and impact energy. Structural engineers have recognised that much of the member rotation is concentrated in a small region referred to as the plastic hinge and because of the complexity of the problem this has been quantified mainly through testing. In this paper, a new plastic hinge approach that is based on well established shear-friction theory is postulated. The generic behaviour of this novel shear-friction hinge is shown to agree with that exhibited in tests. Furthermore, the shear-friction hinge explains the mechanics of the benefits of confinement, such as that due to FRP encasement or steel stirrups, on the rotational capacity of RC members.