GBT formulation to analyse the behaviour of thin-walled members with variable cross-section

The generalised beam theory (GBT) provides a general solution for the linear/non-linear analysis of prismatic thin-walled structures, using bar elements capable of describing the cross-section rigid-body motions and distortions. Nowadays GBT is fully developed for thin-walled members having a large variety of constant cross-sections. This paper provides the extension of GBT for the special case of thin-walled members with variable open cross-section and the limits of its applicability.This offers a new analysis method for structures as box shaped bridges, beams, pylons of variable cross-section, conical shell towers, hyperbolic towers, etc. Regarding the 2nd order analysis, the effect of pre-buckling shear stresses is neglected.