The yield strength and Young’s modulus of aluminum alloy decrease rapidly with the temperatures in a fire

which makes the failure modes of thin-walled aluminum alloy axial compression member with irregular section more complicated.By using the finite element method

deformation shape along the member and stress evolution at the mid-span cross section of the axially loaded aluminum alloy member at a given high temperature were presented.Interactions of local-distortional buckling modes were illustrated by deformation shape and stress evolution curves.Degradation of yield strength and Young’s modulus of aluminum alloy adopted the description of EN1999-1-2.Ultimate strengths of aluminum alloy members at high temperatures obtained from finite element analysis were compared with the design code of EN1999-1-2.Comparison results show that the design code is rather conservative.