INELASTIC BEHAVIOR OF SINGLE ANGLE COLUMNS.

Abstract

The study examines the behavior of pinned-end, centrally loaded columns of monosymmetric and asymmetric cross sections, with emphasis on angle shapes. The investigation covers flexural and flexural-torsional buckling in the elastic and inelastic ranges, which the aim of developing a rational method of predicting the buckling load for cross sections with low torsional rigidity and single or no axes of symmetry. The computer program that was developed takes into account the effect of residual stresses. The properties of the cross section were determined in the laboratory and utilized in the computer model. Full-scale column tests were run to verify the theoretical model. The results shows that equal-legged angles with low width-to-thickness ratio have flexural and flexural-torsional buckling loads that are less than 2% different. It is therefore suitable to continue using a flexural buckling solution for such shapes. This is also true for equal-legged angles with a high width-to-thickness ratio that fail in the elastic range, but in the inelastic range the flexural-torsional buckling load was about 11% less than the flexural buckling load. When the angle is unequal-legged, the flexural-torsional buckling load is always smaller than the corresponding flexural buckling load, in both the elastic and the inelastic ranges. The average difference between the flexural and flexural-torsional load for unequal-legged angle ranges from 3% in the elastic range to 10% in the inelastic range. The average ratio of the experimental results to the minimum of the theoretical results was 0.95 and the coefficient of variation was 0.053. Comparison with the results of other researchers show that it is possible to formulate an empirical formula that can be used in designing columns that are made of monosymmetric or asymmetric cross sections. However, due to the scarcity of data at this stage, it is recommended that the development of such a formula be postponed until additional test data are available. Moreover, in designing any cross section that does not have two axes of symmetry, it is advisable to check the possibility of flexural and flexural-torsional buckling.