Smart metacomposites constitute a new concept of periodical structures including passive and semi-active devices which are optimized to provide new functionalities. Based on recent works on the application of Floquet-Bloch theorem to periodical mechanical systems including frequency-dependent parameters, we propose in this paper an extension to vibroacoustic behavior analysis of smart structures. The objective is to optimize electronic circuits used to shunt some piezoelectric patches distributed on the structure, in order to minimize the acoustic radiation of the structure. The proposed approach is based on the computation of the multi-modal wave dispersion curves into the whole first Brillouin zone of the structure, and associated propagation characteristics in the acoustic fluid. The impedance of the shunt circuit is then optimized in order to render the acoustic waves evanescent. The design is performed on the infinite periodic structure, and the smart metacomposite is finally integrated in a finite structure for validation purposes.