A laminated composite material structure, in the form of a load-bearing rib of a wing of an aircraft, comprises an upper laminated portion, which is angled with respect to a middle laminated portion, and a curved corner portion being continuous with and interposed between the upper and middle portions. (The rib has a curve that connects the upper and middle portions, which are perpendicular or transverse to each other). The corner portion is in the form of a kinked portion or joggled, that is, the portion includes two regions of positive curvature (concave regions) and a region of negative curvature (convex region) interposed therebetween, whereby the formation or propagation of delaminations or cracks at the bend between the middle and upper portions, due to fuel pressure loading and low through-thickness strength, may be reduced.