This paper deals with the formal specification and verification of dynamic reconfigurations of component-based systems. To validate such complex systems, there is a need to check model consistency and also to ensure that dynamic reconfigurations satisfy architectural and integrity constraints, invariants, and also temporal constraints over (re)configuration sequences. As architectural constraints involve first-order formulae, and a behavioural semantics of reconfigurations gives rise to infinite state systems, we propose to associate proof and model-checking within the well-established B method, to support the modelling of such systems and the (partial-)validation of their dynamic reconfigurations. The objective of the paper is twofold. First, given a hierarchical B model of component-based architectures, we validate it by proving its consistency. Second, given linear temporal logic formulae expressing the desirable dynamic behaviour of the system, we validate reconfigurable system architectures by using bounded model-checking tools supporting the B method. The main contributions are illustrated on the example of a HTTP server architecture.