Independent software systems have been joined together to form alliances known as System-of-Systems (SoS). SoS are composed of constituent systems and deliver behaviors as a result of the combination of their individual functionalities. In both, single systems and SoS, the prediction of quality at design-time is of utmost importance. Among several quality attributes (QA) a SoS should cope with, availability is particularly important. Given the critical nature of several domains supported by SoS, failures and unavailability could lead to risks and losses to the SoS users. SoS are then required to be highly available. However, while the strategies to deal with availability in single systems are well-known, techniques to predict and enhance availability at SoS level while considering its inherent dynamics can be still investigated. The main contribution of this paper is the establishment of an architectural strategy at SoS level to enable a simulation-based measurement of availability at SoS architectural descriptions. Preliminary results reveal that the established strategy can be successfully used for the purpose of measurement of the QA availability in SoS architectures.