The paper describes the development of a new structural system for short and medium span bridges wherein use is made of both advanced composites and conventional materials such as concrete. The concept uses prefabricated composite tubes as girders which are then filled with concrete, after which a conventional precast or cast-in-place, or advanced composite, deck system is integrated to form the bridge superstructure. The paper presents experimental results of large-scale tests aimed towards the structural characterization of the girders, anchorages, and girder-deck assemblies for both serviceability and ultimate limit states.