Software systems usually operate in a dynamic context where their requirements change continuously and new requirements emerge frequently. A single requirement hardly exists in isolation: it is related to other requirements and to the software development artifacts that implement it. When a requirements change is introduced, the requirements engineer may have to manually analyze all requirements and architectural elements for a single change. This may result in neglecting the actual impact of a change. We aim at improving change impact analysis in software architecture for requirements changes by using formal semantics of requirements relations, requirements changes and traces between Requirements & Architecture. In our previous work we presented a technique for change impact analysis in requirements. The technique uses the formal semantics of requirements relations and changes. Its output is a set of candidate requirements for the impact with proposed changes and a propagation path in the requirements model. In this paper we present a complementary technique which propagates requirements changes to software architecture and finds out which architectural elements are impacted by these changes. The formalization of requirements relations, changes and traces between R&A is used to determine candidate architectural elements for the impact of requirements changes in the architecture. The tool support is an extension of our Tool for Requirements Inferencing and Consistency Checking (TRIC). Our approach helps in the elimination of some false positive impacts in change propagation. We illustrate our approach in an industrial example which shows that the formal semantics of requirements relations, changes and traces enables the identification of candidate architectural elements with the reduction of some false positive impacts.