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This paper presents experimental and numerical investigations on the cross-sectional behavior and compressive capacities of aluminum alloy channel section stub columns after exposure to fire. A testing program was performed, including heating tests, postfire material tests, geometric imperfection measurements, and 16 stub column tests. The testing program was followed by a numerical modeling program. Finite-element models were developed to simulate the test responses and conduct parametric studies to obtain additional numerical data. The obtained test and numerical data were analyzed and adopted to perform design analyses, in which the applicability of the relevant room-temperature design rules in the American, European, and Australian/New Zealand codes to the postfire design of aluminum alloy channel sections under compression were examined. The results of the design analyses reveal that all three examined design codes yield excessively conservative and scattered predictions of postfire strengths, owing to the neglect of significant postfire material strain hardening. Then, a new design approach was proposed by rationally considering the material strain hardening. The new proposal was found to offer greatly improved design accuracy and consistency compared to the American, European, and Australian/New Zealand codes, especially for aluminum alloy channel sections after exposure to elevated temperatures above 400°C. [ABSTRACT FROM AUTHOR]

This paper reports experimental and numerical studies on the compression resistances of aluminium alloy equal-leg angle section stub columns after exposure to fire. An experimental programme was first conducted, including heating tests, eight post-fire material coupon tests and sixteen post-fire stub column tests. Following the experimental programme, a numerical modelling programme was conducted, where finite-element models were developed and validated. The validated models were then used to perform parametric studies to derive additional numerical data. Based on the obtained test and numerical data, the relevant design rules used in Europe, China, America, Australia and New Zealand as well as the continuous strength method were assessed. The assessment results generally show that the current international standards lead to significant conservative and scattered design resistances when used for the post-fire design of aluminium alloy equal-leg angle sections under compression, particularly for those after exposure to elevated temperatures of 300 °C to 550 °C, due to the neglect of significant post-fire material strain hardening. The continuous strength method is found to provide greatly improved design accuracy and consistency over the European, Chinese, American and Australian/New Zealand standards for the post-fire design of aluminium alloy equal-leg angle sections, since it accounts for the post-fire material hardening. • Post-fire compression resistances of aluminum alloy equal-leg angle sections were studied. • Sixteen post-fire stub column tests were conducted. • FE models were developed and validated against the test results, and then used to perform parametric studies. • The European, American, Australian/New Zealand and Chinese codes and the continuous strength method were evaluated. [ABSTRACT FROM AUTHOR]

• Eccentric compression tests on high strength concrete-filled high strength steel tube (HCFHST) stub columns were conducted. • The structural behaviour and resistances of HCFHST stub columns under combined loading were studied. • The eccentric compression test results for HCFHST stub columns were discussed. • FE models were developed to validate against the test results and then used to conduct parametric studies. • The applicability of the existing design codes to HCFHST stub columns under combined loading was evaluated. This paper presents comprehensive experimental and numerical investigations into the structural behaviour and resistances of high strength concrete-filled high strength steel tube (HCFHST) stub columns under combined compression and bending. The combined loading tests were conducted on twelve stub column specimens fabricated from S700 high strength steel square hollow section tubes with two cross-section dimensions and concretes with three grades (C40, C80 and C110). The combined loading test setup, procedures and results, including the failure loads, load–mid-height lateral deflection curves and failure modes, were reported in detail. The failure loads and the evolution of the neutral axis of the HCFHST stub column specimens under combined loading were analysed. The development and distribution of the transverse and longitudinal strains of the outer S700 high strength steel tubes were discussed. The experimental programme was followed by a numerical modelling programme, where finite element models were initially developed and validated against the test results and then used to conduct parametric studies to generate further numerical data. The test and numerical data were used to evaluate the applicability of the relevant design rules, as set out in the European code, American specification and Australian/New Zealand standard, to HCFHST stub columns under combined loading. The evaluation results generally indicated that the European code and Australian/New Zealand standard slightly overestimate the failure loads for HCFHST stub columns under combined loading, while the American specification offers accurate, consistent and safe failure load predictions when applied to eccentrically loaded HCFHST stub columns. [ABSTRACT FROM AUTHOR]

The present paper reports an in-depth testing and numerical modelling programme, to study the post-fire local buckling behaviour and residual resistances of austenitic stainless steel circular hollow section (CHS) stub columns under combined compression and bending moment. The testing programme employed twelve austenitic stainless steel CHS stub column specimens and included heating and cooling of the stub column specimens, post-fire material testing and post-fire combined loading tests. The testing programme was followed by a numerical modelling programme, where finite element models were developed and validated against the test results and then employed to perform parametric studies to generate additional numerical data. It is worth noting that there are currently no design standards established specifically for stainless steel structures after exposure to fire. In this study, the relevant design rules (i.e. cross-section interaction curves) for stainless steel CHS under combined loading at ambient temperature, as set out in the European, American and Australian/New Zealand standards and given in the continuous strength method, were assessed for their applicability to austenitic stainless steel CHS under combined loading after exposure to fire, based on the obtained test and numerical data. The results of the assessments revealed that all the codified design cross-section interaction curves have certain shortcomings, including the lack of rational exploitation of material strain hardening and the use of linear interaction, and thus yield excessively high degrees of conservatism and scatter when used for austenitic stainless steel CHS under combined loading after exposure to fire. The continuous strength method was shown to lead to accurate and consistent post-fire residual resistance predictions for austenitic stainless steel CHS under combined loading, due principally to the rational consideration of material strain hardening. Finally, the reliability of the continuous strength method was confirmed by means of statistical analyses. • The post-fire local buckling behaviour of stainless steel CHS under combined loading was investigated. • A total of twelve post-fire combined loading tests were conducted. • FE models were developed and validated against the test results and then used to perform parametric studies. • The applicability of the codified and CSM design cross-section interaction curves was assessed. [ABSTRACT FROM AUTHOR]

The present paper reports experimental and numerical studies of the minor-axis flexural buckling behaviour and resistances of welded I-section columns made of a newly developed grade EN 1.4420 high-chromium austenitic stainless steel. The structural testing programme comprised ten pin-ended column tests as well as supplementary measurements of the initial global and local geometric imperfections of the column specimens. The structural testing programme was accompanied by a numerical modelling programme, including a validation study, where column finite element models were developed and validated against the experimental results, and a parametric study, where the validated column finite element models were employed to generate an additional numerical data bank over a broad spectrum of cross-section dimensions and member effective lengths. The obtained test and numerical data, were adopted to evaluate the applicability of the design provisions for normal stainless steel welded I-section columns, as set out in the current European code and American design guide, and cold-formed doubly symmetric section columns, as given in the existing Australian/New Zealand standard and American specification, to the new high-chromium stainless steel welded I-section columns. Overall, it was found that (i) all the four considered codes can be safely extended to cover the design of high-chromium stainless steel welded I-section columns, except for the American specification, which results in unsafe flexural buckling resistance predictions, and (ii) the most accurate and consistent design flexural buckling resistances were obtained by using the European code. • The flexural buckling behaviour of welded I-section columns made of a new high-chromium stainless steel were studied. • Ten pin-ended high-chromium stainless steel welded I-section column tests were performed. • FE models were firstly developed and validated against the test results, and then adopted to conduct parametric studies. • The applicability of the current codified flexural buckling design rules was evaluated. [ABSTRACT FROM AUTHOR]