A semi-finished product (1a) has a tubular sleeve element (4) which extends along a longitudinal axis (A) and has a substantially rectangular cross-section and at least a first (3a) and at least a second (3b) strut element, wherein the first strut element (3a) extends from a first edge of the tubular sleeve to the second edge which lies opposite it with respect to the longitudinal axis, and the second strut element (3b) extends along the other diagonal between the associated edges. The strut elements (3a, 3b) are advantageously designed and arranged such that they absorb compressive forces but not tensile forces. The product can be fabricated completely from a fiber-reinforced plastic and may be integrated in construction elements and surface elements.