The glass fibre reinforced ‘Schöck ComBar’ plastic reinforcement is permanently usable under high stresses and is thus a safe alternative to steel reinforcements. That is the result of an elaborate series of tests carried out by the structural component manufacturer Schöck together with the TU Munich and the German Institute of Building Technology (DIBt, Berlin). For the accurate determination of the endurance tensile strength, a ‘durability concept’ had to be developed on the basis of various existing test programs. The values determined from this were the basis for the general building authority approval (DIBt, Z-1.6-238) for the ComBar bar with a nominal diameter of 16 millimetres. Schöck is at present the only German manufacturer with an approval for a GRP reinforcing bar.