Buckling of fixed-ended lean duplex stainless steel hollow columns of square, L-, T-, and +-shaped sections under pure axial compression—a finite element study

Abstract

This paper presents a finite element (FE) study on fixed-ended LDSS slender hollow columns with square (SHC), and non-rectangular hollow columns (NRHCs) viz., L- (LHC), T- (THC), and +- (+HC) shaped cross-sections subjected to pure axial compression using Abaqus software. SHC columns with thicknesses of 5.25mm and 2.0mm, which lie in Class 3 (stocky) and Class 4 (slender) sections, respectively, as per EN 1993-1-4 were considered in the study as referral sections. Variations in buckling strength with changes in the cross-sectional shapes were studied by considering NRHCs having equal material cross-sectional areas (or equal material consumption) as that of SHCs over a range of column lengths. The FE results of SHC and NRHCs were then compared with the design strengths predicted by the EN1993-1-4 and ASCE 8-02 specifications. Good agreements between the FE strengths and codal predictions have been observed, except for the ASCE 8-02 prediction of LHC where it over predicts the FE strengths. At both the slenderness regime (i.e., low and high slenderness values) of Class 3 sections and high slenderness regime of Class 4, all the sections exhibit similar structural capacities. Cross-sectional shape is found to become increasingly significant with decreasing member slenderness in Class 4 sections. In Class 3 sections, compared to SHC there is a nearly linear variation in strength (increased for +HC, similar behavior for THC and decreased for LHC) up to λ¯∼2.0, then it stabilizes out. After, λ¯∼2.0, Pu for +HC showed ∼30% higher; THC showed similar strength; and LHC showed∼20% lower than the corresponding value for SHC, indicating that +HC has an improved ultimate strength for all the ranges of λ¯. The strength enhancement as compared to that of SHC are ∼10%, 50%, and 90% higher for LHC, THC, and +HC, respectively, for Class 4 sections. Based on the reliability analyses it is recommended that both the codes can be adopted for all the design of fixed-ended LDSS columns except for LHC, wherein a suitable modification may be employed after systematic studies.