Assembled structures involve non-linear phenomena, as contact or friction, localised at each joint interface. In addition, sources of uncertainties are mainly re- sponsible for deviation between the effective behaviour of the structure and results from deterministic simulations. This work aims to provide a pragmatic approach to robustly characterise the vibrational behaviour of an assembled structure considering the joints parameters variability. This approach would be useful for robust design of solutions, such as solutions for damping vibrations, dedicated to assembled structures and taking into account the variability of the real behaviour of each joint. It is based on a non-intrusive approach referred as the Stochastic Model Reduction (SMR) which is used to identify a simple but sufficient stochastic model of bolted joint.