Size Effect in Concrete and Reinforced Concrete Structures

There is much experimental evidence on size effect in concrete and reinforced concrete (RC) structures. blem has two aspects - statistical and deterministic. Although statistical aspects are not negligible, the size effect on the .L.LV'_.__..__LL_.___.._..__..,_.. strength is controlled by the structural energy due crete cracking. a stable crack growth before reaching peak possible, strong size effect may be expected. crack growth not possible, structure fail at initiation no size effect. any small concrete and RC structure relatively crack O"'-rrn:-.r-r is possible. a consequence, any small structure exhibits a vely ductile behavior and size effect which is at least in a limited range always present. There is no general size law, however, it may be useful to classify structures in two classes: (1) of positive geometry - size effect strong only a limited size and (2) Structures of negative geometry - size broad size range. 665 1 size effect problem two aspects: (1) Statistical and terministic (mechanical). Although the statistical aspects 1939) are not negligible, it been generally agreed that the reason for the size effect in concrete cracking and related struc- energy release (Bazant, 1984). From deterministic the formulation of the size effect relationship has been past principally treated in two different ways: (1) Based on ex- perimental results, for particular problem, without any theory behind and (2) based on a theory, general size effect laws have formulated which in a close form the nominal structu- ral for any geometry type with it's The first is practice and it covers only a limited size a certain pro bl em The second (theoretical) rely on the assumptions which need not to be generally fulfilled. Currently, two major completely opposite types of theoretical scaling laws for concrete structures exist.