An open-channel stiffener for stiffening a panel has a bonding flange for bonding the stiffener to the panel through a bondline formed between the bonding flange and the panel to form a stiffened panel. The open-channel stiffener has a cross-sectional shape that aligns, or substantially aligns, a shear center of the stiffener with a centroid of the stiffener and aligns the shear center proximate an edge of the bondline, and removes the need for a radius filler noodle. A plurality of perforations may be formed through the bonding flange to permit an adhesive to wick into the perforations and create a mechanical interlock between the bonding flange and the panel.