Overall stability behavior of annealed cold-formed thick-walled SHS and RHS steel tubes

Abstract

Previous researches on cold-formed steel members are mainly focused on non-annealed sections while research on annealed sections is quite limited. This research is focused on the material properties and overall stability behavior of annealed cold-formed thick-walled SHS and RHS steel tubes. An experimental study including the material property tests on axially compressed annealed cold-formed thick-walled SHS and RHS steel tubes was presented in this paper. The material properties were compared with that of non-annealed sections and it was shown that annealing process can improve the ductility of coupons. The test results were used to validate the finite element analysis which provided the basis for proposing the column curves. Then the curves were compared with the column curves in the Chinese codes and North American specifications. It was found that most of the test and FEA points were above the curves of GB 50018-2002 and AISI which indicated that the column curves in these codes were not suitable for annealed thick-walled steel members. Finally, the column curves of annealed and non-annealed sections were compared and the effect of residual stress was studied.