The paper intends to widely develop the use of a new methodology for the design and optimization of composite materials and structures. Based on the coupling of reliability methods and homogenization techniques, such approach allows the integration of uncertainties at different scales in the problem analysis (i.e. from the microscopic scale of the composite material components up to the macroscopic scale of the structure) and the investigation of their consequences in the failure prediction. The principles and implementation steps of such original method have already been described in details (Int. J. Mech. Sci. 53 (2011) 935-945; Eng. Fail. Analysis 18 (2011) 988-998). This work focuses on its application and significant progress allowed in the design phase for engineering composite materials. Illustrations are presented on the case of a civil engineering structure, namely the Laroin footbridge (France) with carbon epoxy stay cables, and highlight reliability-based innovations and exploitations regarding the structure optimization
