Size effect on structural strength: a review

The article attempts a broad review of the problem of size effect or scalin g of failure, which has recently come to the forefront of attention because of its importance for concrete and geotechnical engineering, geomechanics, arctic ice engineering, as well as for designing large load-bearing parts made of advanced ceramics and composites, e.g. for aircraft or ships. First , the main results of Weibull statistical theory of random strength are bri efly summarized, and its applicability and limitations described. In this t heory as well as plasticity, elasticity with a strength limit, and linear e lastic fracture mechanics (LEFM), the size effect is a simple power law, be cause no characteristic size or length is present. Attention is then focuse d on the deterministic size effect in quasibrittle materials which, because of the existence of a nonnegligible material length characterizing the siz e of the fracture process zone, represents the bridging between the simple power-law size effects of plasticity and of LEFM. The energetic theory of q uasibrittle size effect in the bridging region is explained, and then a hos t of recent refinements, extensions and ramifications are discussed. Commen ts on other types of size effect, including that which might be associated with the fractal geometry of fracture, are also made. The historical develo pment of the size-effect theories is outlined, and the recent trends of res earch are emphasized.