A multiscale approach for modeling fatigue crack growth in concrete. (May 2017) - Simon, Keerthy M.
Highlights: Effects of different size constituents in concrete on fatigue crack growth is studied. Aggregat bridging is included by linking macroscale and mesoscale properties. Number of failure load cycles studied using the analogy of microcracks with human population growth. Model is robust as it accounts for mix proportions, size effect and variable loading. Abstract: A linearized stress intensity factor (SIF) is derived for concrete through a multiscale approach by considering the predominant process zone mechanisms such as aggregate bridging and microcracking. This is achieved by considering a bridging zone and a microcrack at the macrocrack tip. The bridging zone resists the crack growth through aggregate bridging mechanism. The SIF thus derived is further used in developing an analytical model which predicts the entire crack growth curve for plain concrete by making use of the concepts of dimensional analysis and self similarity in conjunction with the human population growth model. This model is validated using experimental data reported on normal strength, high strength and self consolidating concrete. Through sensitivity analyses it is shown that the specimen size plays an important role in the fatigue crack growth process of concrete.