Document Type

Concrete structures paper

Publication details

Visintin, P & Oehlers, DJ 2014, 'Mechanics solutions for quantifying ductility and moment redistribution at all load levels', in ST Smith (ed.), 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23), vol. I, Byron Bay, NSW, 9-12 December, Southern Cross University, Lismore, NSW, pp. 301-306. ISBN: 9780994152008.

Peer Reviewed



For the efficient design of reinforced concrete beams and frames, moment redistribution is used to: reduce the absolute maximum magnitude of the moment in the critical region; equalise the critical moments at either side of interior columns and fully utilise the capacity of the non-critical regions of a member. Although important in design, moment redistribution has historically proved to be difficult to quantify due to the complexity of quantifying hinge rotations. In this paper a framework used to develop mechanics based equations to quantify the moment rotation characteristics of reinforced concrete hinges is presented. This framework directly applies partial interaction theory in the tension region to simulate the mechanisms associated with slip of the reinforcement relative to the surrounding concrete as cracks widen. While in the compression region, shear friction theory is used to describe the formation and failure of concrete softening wedges. Mechanics based solutions for moment redistribution at all load levels is presented and it is shown that at the ultimate limit state mechanics based closed form solutions simple enough for use in routine design can be developed.