Search

• A series of compression tests to investigate member buckling behaviour and ultimate strengths of cold-rolled aluminium alloy channel columns are performed. • The aluminium alloy 5052-H36 materials are used to fabricate the cold-rolled aluminium structural channel columns. • The observed failure modes are flexural, flexural-torsional and local-global interaction buckling failure modes. • The experimental results are compared with predictions by current Australian/New Zealand, North American and European design specifications. Cold-rolled aluminium alloy sections have been recently introduced in Australia as newly developed thin-walled products. To fabricate these sections, the roll-forming process used in cold-formed steel production has been employed, which has proven to be more cost-effective than the conventional extrusion process. This paper describes a series of compression tests to investigate member buckling behaviour and ultimate strengths of cold-rolled aluminium alloy 5052-36 channel columns. Twenty-eight specimens of three commercially available sections (C10030, C25025 and C40030) were tested at the University of Sydney. Two configurations of end boundary conditions were specially designed to capture flexural, flexural-torsional and local-global interaction buckling failure modes. Prior to testing, initial geometric imperfections were measured using a laser scanning method, and flat/corner coupons were tested to determine compressive and tensile strengths of the aluminium alloy material. The experimental results are compared with ultimate column strength predictions by current Australian/New Zealand, North American and European design specifications for aluminium structures. Additionally, the test results provide data for calibration of finite element models of cold-rolled aluminium structural members for use in parametric and similar studies. A companion paper describes such parametric study and the derivation of new design guidelines for member buckling of cold-rolled aluminium channel columns based on the numerical parametric data and the experimental data presented herein. [ABSTRACT FROM AUTHOR]

• Experiments on the member buckling and ultimate strengths of cold-rolled aluminium alloy channel columns are performed. • The aluminium alloy 5052-H36 materials are used to fabricate the cold-rolled aluminium structural channel columns. • Non-linear FE models are developed using ABAQUS to simulate laboratory experiments and calibrated against the test results. • A parametric study based on FE models is performed to extend the data by varying cross-section dimensions and member lengths. • Experimental and numerical results are ued to calibrate the new design equations for cold-rolled aluminium alloy columns. The paper first presents the development of detailed finite element (FE) models for investigating the member capacity of cold-rolled aluminium alloy 5052-36 channel columns. The numerical non-linear FE models are developed using the commercial FE software package ABAQUS to simulate laboratory experiments and calibrated against the test results. The experimental program was performed by the authors at the University of Sydney and the detailed test results are fully described in a companion paper. The calibrated numerical FE models with actual mechanical properties and measured geometric imperfections in analyses accurately predict the experimental results and behaviours, including flexural and flexural-torsional buckling as well as local-global interaction buckling failure modes. A parametric study is subsequently performed to extend the data range by varying cross-section dimensions and member lengths. The effects of loading eccentricity positions and initial geometric imperfections are also considered in the parametric study. The experimental and numerical results are compared with design strength predictions from current Australian/New Zealand, American and European specifications for aluminium structures in the companion paper. In this paper, the Direct Strength Method (DSM) for the design of compression members as per the Australian/New Zealand standard AS/NZS 4600 for cold-formed steel structures is adopted for comparison. The DSM design rules for cold-formed steel compression members are found to provide more accurate predictions than those of current specifications for aluminium structures and therefore used to propose improved design equations for cold-rolled aluminium alloy columns. Finally, a reliability analysis is performed to evaluate the safety level of current design specifications and the proposed design rules. [ABSTRACT FROM AUTHOR]

• The compressive behaviour of square RACFSST stub columns after exposure to fire is investigated. • Twelve post-fire compression tests are conducted. • The influences of heating durations and RCA replacement ratios are discussed. • Thermal and mechanical FE models are validated against test results and then used to conduct parametric studies. • The relevant design codes are assessed against the test and FE data. Experimental and numerical studies on the cross-section compressive behaviour and residual resistances of square recycled aggregate concrete-filled stainless steel tube (RACFSST) stub columns after exposure to fire are reported in this paper. An experimental programme was firstly carried out on twelve stub column specimens with three recycled coarse aggregate replacement ratios (0%, 35% and 70%) after exposure to the ISO-834 standard fire for 0 min (i.e. at ambient temperature), 15 min, 30 min and 45 min. The test results, including load–end shortening curves, failure loads and failure modes, were presented, with the initial compressive stiffness and confinement effect analysed. The experimental programme was followed by a numerical modelling programme, where thermal and mechanical finite element models were developed and validated against the test results and afterwards used to conduct parametric studies to generate additional numerical data over a wide range of cross-section dimensions. Based on the test and numerical data, the relevant design rules for square natural aggregate concrete-filled carbon steel tube stub columns at ambient temperature, as specified in the European code, Australia/New Zealand standard and American specification, were evaluated, using post-fire material properties, for their applicability to square RACFSST stub columns after exposure to fire. The evaluation results generally revealed that the European code and Australian/New Zealand standard led to a good level of design accuracy, while the American specification resulted in slightly conservative post-fire cross-section compression resistance predictions. [ABSTRACT FROM AUTHOR]

• The web crippling behaviour of cold-formed steel channels with elongated un-stiffened and edge-stiffened web holes under end-two-flange loading condition was studied numerically. • The results of a total of 1536 new finite element analysis were reported. • Design formulae in the form of the web crippling reduction factors were proposed. • The direct strength method (DSM) equations were also presented to evaluate web crippling strengths. Over the last decade, cold-formed steel (CFS) channels with circular edge-stiffened web holes have been widely used in New Zealand. In the case of web crippling, previous studies have revealed that the use of an edge-stiffened hole almost results in the same strength as an equivalent channel-section having a plain web. Such circular edge-stiffened web holes could be extended to elongated holes. In terms of web crippling, however, no experimental or numerical works on such elongated holes were reported in the literature. In this paper, a numerical investigation was carried out to investigate the web crippling behaviour of CFS channels with elongated un-stiffened and edge-stiffened web holes under the end-two-flange (ETF) loading condition. The finite element (FE) models were validated against the test results of CFS channels with circular edge-stiffened web holes; good agreement in terms of the load-displacement relationships and failure modes was shown. A parametric study was then conducted, comprising 1,536 FE models. Compared to CFS channels with a plain web, for the case of channels with an elongated un-stiffened web hole, the average web crippling strength reduction for sections with an aspect ratio of two and three was 21 % and 36 %, respectively. However, for an elongated edge-stiffened hole, the reduction in the web crippling strength was only 5 % and 8 %, respectively. Finally, design equations in the form of the web crippling reduction factor (R p) and the equations based on the direct strength method (DSM) for CFS channels with elongated web holes under ETF loading conditions were recommended. [ABSTRACT FROM AUTHOR]

The flexural buckling behaviour and resistances of press-braked stainless steel Z-section columns are investigated in this paper, based on experiments and numerical modelling. An experimental investigation was conducted on two press-braked stainless steel Z-sections and included material testing, initial geometric imperfection measurements and twelve fixed-ended column tests. Minor-axis flexural buckling was observed for all press-braked stainless steel Z-section column specimens upon testing. The key obtained fixed-ended column test results, including failure loads, load–deformation histories and failure modes, were fully reported. Following the experimental investigation, a numerical investigation was performed, with finite element models developed to validate against the fixed-ended column test results and then used to conduct parametric studies to generate additional numerical data. On the basis of the test and numerical data, the relevant buckling curves, as specified in the European code, American specification and Australian/New Zealand standard, were evaluated and shown to provide accurate and consistent flexural buckling resistance predictions for press-braked stainless steel Z-section columns. • The flexural buckling behaviour of press-braked stainless steel Z-section columns was studied. • Twelve fixed-ended column tests were conducted. • FE models were developed to validate against the test results and then used to perform parametric studies. • The codified buckling curves were assessed, showing good design accuracy and consistency. [ABSTRACT FROM AUTHOR]