A coupled lattice and nite element model for fracture in composite concrete pavements

Abstract

Recent research in the United States has focused on the design, construction, and performance of composite concrete pavements - i.e., two heterogeneous concrete layers placed soon after the other using "wet-on-wet" techniques. While these pavements offer many benefits, they also introduce some uncertainties, including the possibility of thermally, hygrally, or mechanically induced fracture and separation at interface of the concrete layers. Despite over 40 years of experience in Europe that has yet to observe debonding in composite concrete pavements, debonding remains a commonly held concern among pavement engineers in the United States. To complement field evidence from Europe in addressing debonding concerns, this dissertation describes the development of a computational tool specifically designed for the simulation of a composite pavement under thermal, hygral, and mechanical loads. This simulation would be difficult using an exclusively continuum approach such as finite element methods in view of the heterogeneity of the pavement materials and the associated lack of smoothness in the crack propagation path. Given that the problem involves both heterogeneous media and the interface between the pavement layers, in this thesis the simulations are instead conducted using three-dimensional lattice modeling with emphasis on the potential for mixed-mode fracture at the interface. This discrete approach is coupled with a finite element model for plate behavior away from the potential cracking zone. The intricacies of that coupling are discussed and illustrated through numerical tests and examples.