Local Buckling of Aluminum Alloy Angles under Uniform Compression

Metal members are able to exhibit plastic deformations whose amplitude depends on the local slenderness of the plate elements constituting the member section, provided that global instabilities are prevented. This local slenderness depends on the width-to-thickness ratios of the plate elements and governs the occurrence of local buckling which can be developed either in elastic or in plastic range. Aiming at the development of a ductile behavior, the occurrence of local buckling in elastic range has to be prevented to assure the development of ultimate behavior in plastic range. To this scope, the width-to-thickness ratios of the plate elements constituting the member section have to be properly limited. Wide experimental research dealing with the influence of width-to-thickness ratios on the local buckling of heat-treated aluminum alloys has been recently completed with the aim of providing Eurocode 9 with the background data necessary for setting up classification criteria specific to aluminum members. The aim of the developed experimental activity is evaluation of the relationship between the strain corresponding to the complete development of local buckling and the slenderness parameters of the plate elements composing the section. This relationship has been derived by analyzing the results obtained from a great number of stub column tests carried out on specimens having width-to-thickness ratios covering the whole range of variability of commonly extruded profiles. The whole experimental program has dealt with square hollow section, rectangular hollow section members, channels, and angles made of 6,000 series alloy, provided by the major European aluminum industries. This paper presents and discusses the results of the part of the experimental program regarding aluminum alloy angles subjected to local buckling under uniform compression. Sixty-four stub column tests have been carried out at the Material and Structure Laboratory of the Department of Civil Engineering of Salerno University. These experimental results and their interpretation are presented in this paper. In addition, a classification criterion accounting for the interaction between the two slenderness parameters of the cross-section is proposed.