The alkali-aggregate reaction (AAR) in concrete structures consists in a chemical deleterious reaction between alkalis liberated during hydration of cement and reactive minerals present on aggregates. The process leads to the formation of a gel, which in presence of hydroxyl ions expands, causing cracks in concrete, promoting its volume variation, followed by reduction of important properties, such as the Young´s modulus and mechanical strength. Modeling of a structure subjected to AAR expansion may predict the structural displacements and strains due to the reaction, enabling programming efficient structural maintenance operations , reducing temporary interruptions and also increasing safety conditions. As such, this work presents a parametric model for simulating the orthotropic concrete expansion due to alkali-aggregate reaction, based on Carrazedo and Lacerda, 2008 [1].