Buckling Analysis using Fictitious Axial Forces and Its Application to Cable-Stayed Bridges with HSB800 Steel

Abstract

Buckling Analysis using Fictitious Axial Forces and Its Application to Cable-Stayed Bridges with HSB800 Steel Elastic buckling analysis;Inelastic buckling analysis;Effective length;Fictitious axial force;Steel cable-stayed bridge;HSB800 steel; System buckling analysis is usually used to determine the critical buckling load in the buckling design of cable-stayed bridges. However, system buckling analysis may yield unexpectedly large effective lengths of the members subjected to a relatively small axial force. This paper proposes a new method to determine reasonable effective lengths of girder and tower members in steel cable-stayed bridges using fictitious axial forces. An improved inelastic buckling analysis with modified tangent modulus is also presented. The effective lengths of members in example bridges calculated using the proposed method are compared with those obtained using the conventional buckling analysis method. The proposed method provides much more resonable effective lengths of the members. When girder and tower members are built with HSB800 steel instead of conventional steel, the effective lengths of the members under a small axial force slightly decreases in the inelastic buckling analysis without fictitious axial forces, while the proposed method that considers fictitious axial forces provides almost no changes in such lengths.