A replaceable steel-hybrid composite beam with an adhesive joint bridge panel and removable high-strength bolt-shear bond is proposed. In order to analyze the influence mechanism of different joint forms on the mechanical properties of the fully assembled composite beam in the positive moment zone, four composite beams with different bridge panel joint forms were designed and prepared, and the static loading test was completed. The mechanical characteristics of each specimen, such as failure mode, bearing capacity, ductility, flexural stiffness and interface slip were analyzed. The results show that compared to cast-in-place beams, which fail in bending, fully assembled composite beams exhibit bending-shear failure, with the main crack occurring near the adhesive joint, indicating concrete cohesion failure. Linear, stepped and dovetail joint beams showed a reduction in flexural capacity compared to cast-in-place beams by 4.78%, 2.07% and 2.04% respectively. The overall elastic stiffness of composite beams is not significantly affected. The elastic stiffness of the lap joint beams is reduced by 0.55%, 5.43% and 2.06% respectively. The slip at the end of the cast-in-place beams is the largest, while the maximum slip of fully assembled composite beams occurs near the joints. Among different joint forms, the tongue and groove joint exhibits the best performance in terms of strength and stiffness. Substituting adhesive joints for traditional wet joints enables fully assembled construction as an alternative to cast-in-place methods, greatly enhancing assembly efficiency, and providing construction advantages for applications in prefabricated engineering projects.. Finally, based on plastic theory, the calculation formula for the flexural capacity of fully assembled composite beams considering the influence of high-strength bolted joints and rubber joint bridge panels is proposed.