Ultimate Strength of Arches with Bracing Systems

The ultimate load carrying capacity of bridge arches is investigated for the case where they fail by inelastic lateral instability associated with the flexural-torsional deformation of the arch rib. The arch bridge is composed of twin ribs connected to one another by a lateral bracing system. The ribs are subjected to a uniformly distributed vertical load. A parametric study is carried out for several representative cases by using a finite element method. The effects of the stiffness, location and type of the lateral bracing system on the inelastic behavior of twin arches are evaluated. Ultimate strength versus slenderness ratio curves for various twin arches are obtained. The possibility of introducing an effective length concept for lateral buckling is also examined and a comparison is made with the recommendations of existing codes for arch bridges