Abstract: A composite structure, formed of construction elements capable of various uses. The elements are associated with one another for the construction of buildings and of fixed and movable fittings, also for use in maintenance, and for other purposes, for example in public works. The composite structure comprises; a primary subassembly which in turn comprises C-section sleeves each having angulate flanges; a supporting and connecting principal beam, having wall faces with longitudinal, mutually opposed retaining cavities, and, to insure the required rigidity of the sub-assembly, transversely bracing and connecting bridges, slid into and engaged with the sleeves and beams at variable spacing between the bridges. Each bridge acts on at least two beams; which have substantially the shape of C, U or omega profiles. The bridges are placed opposite to one another on at least a portion of the length of the internal corners of the retaining flanges of the C-section sleeves.