Size e ect

This paper surveys the available results on the size e€ect on the nominal strength of structures Ð a fundamental problem of considerable importance to concrete structures, geotechnical structures, geomechanics, arctic ice engineering, composite materials, etc., with applications ranging from structural engineering to the design of ships and aircraft. The history of the ideas on the size e€ect is brie ̄y outlined and recent research directions are emphasized. First, the classical statistical theory of size e€ect due to randomness of strength, completed by Weibull, is reviewed and its limitations pointed out. Subsequently, the energetic size e€ect, caused by stress redistributions due to large fractures, is discussed. Attention is then focused on the bridging between the theory of plasticity, which implies no size e€ect and is applicable for quasibrittle materials only on a suciently small scale, and the theory of linear elastic fracture mechanics, which exhibits the strongest possible deterministic size e€ect and is applicable for these materials on suciently large scales. The main ideas of the recently developed theory for the size e€ect in the bridging range are sketched. Only selected references to the vast amount of work that has recently been appearing in the literature are given. # 1999 Published by Elsevier Science Ltd. All rights reserved.