Improved system buckling analysis of effective lengths of girder and tower members in steel cable-stayed bridges

This paper proposes an iterative system buckling analysis to determine reasonable effective lengths of girder and tower members in steel cable-stayed bridges. The modifications include the addition of a fictitious axial force to the geometric stiffness matrix with iterative eigenvalue computations. After verifying the proposed method by analyzing steel frames, we apply it to cable-stayed bridges with different center spans and girder depths. The effective lengths of members in these example bridges by the proposed method are compared with those found using conventional buckling analysis. The effects of the proposed method on slenderness ratios and compressive strengths are also discussed.