Why do we need ductility in reinforced concrete structures?


Eurocode 2, due for publication later in 2004, is to include a classification for concrete reinforcement ductility. Three classifications ( A, B and C ) are defined according to the ratio of the ultimate tensile strength to the yield strength, and to the strain at maximum stress. Under deformation, a reinforced concrete slab will rotate at the fixed ends, and it is important to ensure that the amount does not exceed the rotation capacity of the section. Analysis is usually by redistribution. There is a relationship between the ultimate rotation capacity of the section and the ratio of the neutral axis depth to the effective depth, and practical rules have been devised relating the percentage redistribution to this ratio. The design relationships in Eurocode 2 vary according to the reinforcement ductility. It is shown that many design procedures are more dependent upon plastic methodology than is immediately apparent, and that it is often difficult to establish the required level of ductility and the stage at which reinforcement ductility becomes insufficient. 5 refs.

Primary author(s): Beeby A

Source: Concrete

             Vol.38, No.5, 2004, p.27-29


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