Flexural-Torsional Buckling and Ultimate Resistance of Parabolic Steel Arches Subjected to Uniformly Distributed Vertical Load

Abstract

This paper focuses on the flexural-torsional buckling and ultimate resistance of parabolic steel arches with box sections subjected to full-span uniformly distributed vertical load by using finite-element numerical analyses. First, analyses on prebuckling internal forces and flexural-torsional buckling loads are performed and compared with the existing theories. They show that parabolic arches under uniformly distributed vertical load are actually subjected to combined axial compressive and in-plane bending actions, rather than pure compression in the classic theory. Because the bending moment is substantial for shallow arches, the classic theory with the assumption of pure compression does not predict exactly the flexural-torsional buckling load. Second, the flexural-torsional ultimate resistance of parabolic arches is explored based on extensive finite-element numerical results, resulting in a design method based on a modified slenderness. The rise-to-span ratio is found to have a great effect on the flexural-torsional performance and resistance of parabolic arches, and for shallow arches the existing design method based on axial compressive force at the arch end cannot give good predictions for the resistance of arches. By introducing and adopting the modified slenderness of arches with distributed vertical load, which accounts for the effect of the in-plane bending moment, the column curve