ABSTRACT
This paper derives a geometrically nonlinear formulation for pin-ended circular steel tubular arches, typically in a cladded roofing structure, at elevated temperature. An energy method is used to derive the in-plane equations of equilibrium in differential form, which are solved to produce an analytic solution in closed form, as well as the elastic buckling load under thermal loading, where the thermal strain is treated as a non-mechanical strain in the derivation. It is shown that the arch may buckle in an antisymmetric or in a symmetric snap-through mode, depending primarily on its slenderness and the external load on the arch, and the paper presents prescriptive equations for the buckling loads of the arch as a function of the temperature of the fire. The application of the equations to design is discussed.
