Elastic out-of-plane buckling load of circular steel tubular truss arches incorporating shearing effects

For steel tubular truss arches, calculations of sectional rigidity especially the torsional rigidity, as well as the effect of shear deformation on out-of-plane buckling are not available yet. This paper investigates the sectional rigidities of trusses and the out-of-plane buckling loads of pin-ended circular steel tubular truss arches in uniform axial compression and in uniform bending. Firstly the compression rigidity, flexural rigidity, shear rigidity and torsional rigidity of latticed configuration for trusses are deduced. Then the out-of-plane buckling equations for circular monosymmetric arches incorporating the effect of shear deformation are established using a static equilibrium approach. Lastly the closed form solutions for out-of-plane buckling loads of pin-ended circular truss arches in uniform compression and in uniform bending are obtained. It is found that the axial deformation of chord tubes need be taken into account in the derivation of shear rigidity and torsional rigidity of latticed configuration. Due to the curved arch profile, the effect of shear deformation on out-of-plane buckling loads of truss arches is much smaller than that on straight truss columns.