Abstract: A composite structure has a rod (1) and a collar (2) locked on the rod (1) and composed of two semicollars (12, 22), each extending over an angle smaller than 180.degree. and having lateral longitudinal flanges (12', 12", and 22', 22"), whereat they are linked to each other by clamping bolts (3', 3"). The flanges (12', 22') on one side of the semicollars (12, 22) adhere to each other with their facing plane surfaces (212', 222'), whereas the facing plane surfaces (212", 222") of the flanges (12", 22") on the opposite side of the semicollar (12, 22) are spaced. The rod (1) has at least one outer positioning projection (6', 6"), which is engaged in a corresponding inner positioning recess of the collar (2).