Section 1.3 - Size Effect on Structural Strength

Abstract

This chapter reviews the problem of size effect or scaling of failure, which has recently come to the forefront of attention because of its importance for concrete and geotechnical engineering, geomechanics, and arctic ice engineering, as well as in designing large load-bearing parts made of advanced ceramics and composites, example for aircraft or ships. The main results of the Weibull statistical theory of random strength are briefly summarized and its applicability and limitations are described. In this theory as well as plasticity, elasticity with a strength limit, and linear elastic fracture mechanics (LEFM), the size effect is a simple power law because no characteristic size or length is present. The focus is on the deterministic size effect in quasi-brittle materials which, because of the existence of a non-negligible material length characterizing the size of the fracture process zone, represents the bridging between the simple power-law size effects of plasticity and of LEFM. The energetic theory of quasi-brittle size effect in the bridging region is explained, and followed by a host of recent refinements, extensions, and ramifications.