An improved building panel with increased stiffness and resistance to buckling is disclosed. The panel cross section is characterized by a novel center portion comprised of radially arranged longitudinal stiffening ribs which transition into side portions configured to allow joining of the panels. The configuration of the panel's center section results in an increased moment of inertia as well as higher resistance to positive and negative bending moments and local buckling when compared to existing designs. Additionally, the panel configuration allows curving longitudinally without corrugations. These improvements in the strength of the panel and the elimination of corrugations reduce design constraints on buildings constructed of such panels and allow larger buildings to be constructed.