Crack Propagation in Portland Cement Concrete Beams: Implications for Pavement Design

Hillerborg's fictitious crack model is used to simulate numerically progressive crack development in simply supported concrete beams. The tools used in the simulation are a general-purpose finite element package for the linear elastic aspects of structural response and specially coded iterative program CRACKIT for tracking crack propagation. Data generated in this manner are used to study the specimen-size effect, that is, the dependence of fracture behavior on geometric, boundary, and loading conditions. The numerical approach presented is used successfully to reproduce experimental and numerical results obtained by independent investigators. The main objective for the research is to examine how principles of similitude proposed in recent years and the experience gained in the application of dimensional analysis to concrete pavement data interpretation can aid in the formulation of more mechanistic-based failure criteria, which would eventually lead to improved pavement design procedures. Because of its similarity to conventional fatigue curves, a plot prepared by Gustafsson, of the normalized bending stress against the brittleness number, is found to deserve additional consideration as a possible candidate for this purpose.