Ultimate Load Carrying Capacity of Steel Arches

The spatial elasto-plastic behavior of steel arches is investigated in the case where they collapse due to inelastic lateral instability producing flexural-torsional deformations towards out-of-plane of the arch. A tangent stiffness matrix for large deflections of the spatial members in an elasto-plastic state is newly derived and used in the numerical calculations. Attention is paid mainly to the following parameters, i.e., slenderness ratios, residual stresses, initial lateral deflections, loading directions, and properties of the materials. Their effects on the ultimate load carrying capacity of two-hinged parabolic arches are examined and illustrated in several figures. In addition to the parametric study, a typical numerical example of the ultimate strength analysis of a central-arch-girder bridge is presented as one of applications to the actual bridge.