Due to the increasing software complexity, it has been difficult to manipulate the models that represent them. It is difficult to identify the impact of changes, to modify, or reuse model parts in other projects because the system concerns are, in general, strongly interconnected. Traditional modeling and programming methods use separation method to minimize this coupling, however they consider only one dimension (classes, functions, events). Therefore, the concerns in other dimensions continue scattered and tangled, i.e., they are crosscutting concerns. In this thesis, we applied aspect- oriented concepts in modeling requirements. We define a metamodel to integrate crosscutting concerns that provides a set of activities and mechanisms to facilitate the requirements modularization, traceability, evolution and reuse. These mechanisms are centered in a language that defines new constructs to be used in traditional requirements languages, allowing the separation and composition of crosscutting concerns. We present two detailed case studies to show the proposed metamodel instantiated to a goal oriented requirements model, V-graph.