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Comparison of failure modes obtained from tests and FEA for aluminium alloy CHSs with circular through-holes under axial compression
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This paper presents a finite-element (FE) investigation on the axial compressive capacity of aluminium alloy circular hollow sections (CHSs) with circular holes. The geometrical and material non-linearities were considered in the finite-element analysis (FEA). Two consecutive steps including an eigenvalue analysis and a load-displacement non-linear...
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... axial compressive capacity (Pu) obtained from the FEA and tests were compared against 358 the design strengths (Pp) calculated using proposed design equations. As can be seen in Fig. 13 Table 7, the mean value of the test and FEA-to-design strength ratio Pu/Pp is 0.99, with a COV of 360 0.107. Therefore, the proposed design equations are more accurate than the current design formulae 361 for the axial compressive capacity of aluminium alloy CHSs with circular ...
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... The findings derived from their research were utilized to enhance the shear design guidelines specified in AS/NZS 4600:2005 [26]. Effects of holes on the compressive capacities of aluminium alloy circular hollow sections were investigated by Feng et al [27] by developing experimental and numerical studies, which allows proposing new design equations based on the effective area method as regulated in The American Specification AISI S100-16 [28]. Fang et al ( [29], [30]) studied the effects of web holes on the strength and behavior of back-to-back built-up aluminium alloy stub channel columns based on experimental and numerical investigations; this helps to assess the Australian/New Zealand Standard [31] and American Specification [32] in the design, and proposes the reduction factor equations for the design of these such columns. ...
The paper presents an overview on research of the influence of perforations on the behavior and capacities of cold-formed steel members, with the most common channel sections. The key findings have been incorporated into American Specification with the development of the Direct Strength Method in design. The paper also introduces the application of the Direct Strength Method in previous studies on the impact of perforations on capacities of cold-formed steel channel members. The overview presented in this paper helps researchers to identify gaps for further investigation. Additionally, the obtained investigated results provide designers in better understanding the effects of perforations on the capacities of cold-formed steel channel members. It was found that there is a reduction in sectional capacities of channel sections with an increase in hole dimensions. Also, reduced hole heights and extended hole lengths are proposed to get optimal section capacities while maintaining the unchanged web hole area in general.
... In contrast to steel, the stress-strain curve of aluminum alloys lacks a distinct yield plateau and instead exhibits a continuous and smooth curve. The classical three-parameter Ramberg-Osgood model [4] (hereinafter referred to as the R-O model) has found extensive application in the mechanical analysis of aluminum alloy components [5][6][7]. However, the European standard EN 1999-1-1:2007 [8] (hereinafter referred to as EC9) introduces several other constitutive models in addition to the R-O model. ...
This study aims to examine the effects of various aluminum alloy constitutive models on the behavior of concrete-filled aluminum tubular stub columns under axial compression. The bi-linear model with hardening, the Baehre model, and the Ramberg-Osgood (R-O) model, which follow the European standard (EC9) were analyzed and compared in terms of their ability to describe the stress-strain behavior of aluminum alloy tensile coupons over the full range, and their respective application scenarios were discussed. A total of 74 sets of experimental data results were collected to examine the effects of these three models on the ultimate load of concrete-filled aluminum tubular stub columns. Furthermore, a full-scale model was constructed to analyze the effect of the hardening exponent n in the R-O model on the load-displacement curves. The results show that, apart from the bi-linear model with hardening, the other two aluminum alloy constitutive models are capable of accurately predicting the stress-strain behavior of aluminum alloys throughout the full range. The accuracy of the R-O model is significantly influenced by the calculation methods of n. The Baehre model is found to be more suitable for non-heat-treated aluminum alloys. The simulated ultimate load values obtained from the three constitutive models fall within a deviation range of ±10%, indicating their suitability for practical engineering applications. Among the three models, the R-O model exhibits the highest stability, as changes in the hardening exponent n do not affect the ultimate load but have a significant effect on the load-displacement curves beyond the ultimate load.
... Recently, Krishanun Roy et al. [3,4] highlighted that, in the case of channel section members, the design codes (Aluminium Design Manual [5] Australian/New Zealand Standards [6], Eurocode 9 [7] and Eurocode 3 [8]) are conservative within the 20-30% range, with respect to the experimental tests. The same problem was encountered by Feng et al. [9,10] in the case of the circular hollow sections of the aluminium alloy with holes during compression ...
The aim of this work is to provide an extension of effective thickness method (ETM) in order to evaluate the ultimate response of aluminium members under uniform compression or in bending. It is well known that this approach is applied to evaluate the behaviour of aluminium slenderness sections affected by the local buckling phenomena in the elastic range. Starting from the original form, this approach has been extended for estimating the ultimate behaviour of aluminium members in the plastic region.
... Recently, Krishanun Roy et al. [3,4] highlighted that, in the case of channel section members, the design codes (Aluminium Design Manual [5] Australian/New Zealand Standards [6], Eurocode 9 [7] and Eurocode 3 [8]) are conservative within the 20-30% range, with respect to the experimental tests. The same problem was encountered by Feng et al. [9,10] in the case of the circular hollow sections of the aluminium alloy with holes during compression ...
The ultimate behaviour of aluminium members subjected to uniform compression or bending is strongly influenced by local buckling effects which occur in the portions of the section during compression. In the current codes, the effective thickness method (ETM) is applied to evaluate the ultimate resistance of slender cross-sections affected by elastic local buckling. In this paper, a recent extension of ETM is presented to consider the local buckling effects in the elastic-plastic range and the interaction between the plate elements constituting the cross-section. The theoretical results obtained with this approach, applied to box-shaped aluminium members during compression or in bending, are compared with the experimental tests provided in the scientific literature. It is observed that the ETM is a valid and accurate tool for predicting the maximum resistance of box-shaped aluminium members during compression or in bending.
... 274 Therefore, the design equations of Moen and Schafer [13][14][15][16] for CFS channels with un-275 stiffened holes were modified to improve the prediction of the axial capacity of CFS channels 276 with edge-stiffened holes by multiplying an enhancement factor which was obtained from the 277 bivariate linear regression analysis. A similar approach was reported by Feng et al. [24][25]. It 278 should be noted that the effects of the hole diameter (a), web depth (d), column thickness (t) 279 ...
The use of cold-formed steel (CFS) channels with web holes are becoming 1 increasingly popular. Such holes, however, result in sections becoming more susceptible to 2 lower axial compressive resistance. Traditional holes are normally punched at the web and un-3 stiffened. Recently, a new generation of CFS channels with edge-stiffened holes has been 4 developed by the CFS industry but no information is available in the literature to accurately 5 predict the axial capacity of such sections. The current design guidelines in accordance with 6 the American Iron and Steel Institute (AISI 2016) and Australia New Zealand standards 7 (AS/NZ 4600:2018) do not provide any design rules for CFS channels with edge-stiffened 8 holes. In this paper, a numerical model that accurately simulated results from the experimental 9 testing of CFS channels with edge-stiffened holes under axial compression as published in a 10 previous paper by the authors was employed to carry out a parametric study which involved 11 348 finite element (FE) models. Variables which were examined included column slenderness, 12 stiffener length, fillet radius, hole size, hole location and hole spacing. A comparison of the 13 numerical results with current design rules for CFS channels with un-stiffened holes revealed 14 that the design equations were not accurate for such sections; design equations are therefore 15 proposed in which an enhancement factor is applied to the original equations. The enhancement 16 factor was obtained using bivariate linear regression analysis. The proposed design equations 17 closely predict the enhanced axial capacity of CFS channels with edge-stiffened holes. 18 2
The use of cold-formed steel (CFS) channel sections is becoming popular as the load-carrying members in building structures, and such channel sections are often perforated for the ease of installation of services. However, limited experimental investigation has been reported in the literature for such channel sections under pinned-pinned boundary conditions. In this paper, a total of 16 CFS channel sections with and without slotted web holes were tested under pinned-pinned boundary conditions, and it was shown that all specimens with short lips failed by distortional-local buckling interaction controlled by distortional buckling and all specimens with long lips failed by local buckling. Moreover, the slotted web holes caused the axial capacities to decrease slightly by 2.4% on average for specimens failed mainly by distortional buckling and 6.4% on average for specimens failed by local buckling. A nonlinear elasto-plastic finite element (FE) model was also validated against the test results, a parametric study was conducted using the validated FE model. In addition, the results obtained from the tests and parametric study were compared against the results predicted by the current direct strength method (DSM) in AISI S100–16 for CFS channel sections with web holes. It indicates that the results predicted by the DSM are un-conservative for most CFS channel sections with web holes under pinned-pinned boundary conditions, especially un-conservative by 27.0% on average for CFS channel sections failed by local buckling. Therefore, new design formulas were developed based on the current DSM formulas for CFS channel sections with web holes.
The structural performance and design of extruded high-strength aluminium alloy square hollow section (SHS) columns were presented in this paper. A total of 12 extruded 7A04-T6 aluminium alloy SHS column specimens were tested under axial compression, together with tensile coupon tests and initial global geometric imperfection measurements. The flexural buckling failure mode and axial load versus end shortening and mid-height lateral deflection curves were reported. Based on validated finite element (FE) models, 480 numerical results were generated by means of parametric studies over a broad range of cross-section dimensions, member lengths, proof strengths and strain hardening exponents of the aluminium alloy material. The applicability of current design rules used for normal-strength aluminium alloy columns in European, Chinese and American standards to extruded 7A04-T6 high-strength aluminium alloy SHS columns was evaluated through comparisons with the test and FE results. The analysis results showed that the three standards consistently yielded conservative axial compression resistance predictions by about 9% for extruded 7A04-T6 high-strength aluminium alloy SHS columns. New flexural buckling curves with linear and nonlinear imperfection terms for the Chinese code, as well as modifications to the American specification, were separately proposed, resulting in improved accuracy with significantly reduced scatter. Additionally, the continuous strength method (CSM) was further extended for the flexural buckling design of extruded 7A04-T6 high-strength aluminium alloy SHS columns, and was shown to provide accurate and consistent resistance predictions. Reliability analyses of the codified and the proposed design methods were performed, confirming that the design proposals meet the target reliability indices except the Eurocode approach.
High-strength aluminium alloys are increasingly popular and gaining more prominence in structural engineering. The global buckling behaviour and design of high-strength aluminium alloy circular hollow section (CHS) columns subjected to axial compression are investigated in this study. Ten experiments on CHS specimens with two extruded 7A04-T6 CHS profiles – 165 × 15 and 165 × 7.5 (in mm), were conducted. The material tests and initial geometric imperfection measurements were carried out prior to column tests. The test setup, procedure and results, including failure modes, ultimate resistances and load–displacement curves were comprehensively reported and analysed. Based on the developed and validated finite element (FE) models, an extensive parametric study, over a broad range of member and cross-section slenderness as well as the strain hardening exponents and proof strengths of the high-strength aluminium alloy material, was performed to complement the test data pool. The applicability of current buckling design provisions used for normal-strength aluminium alloy columns in the European, Chinese, American, Australian & New Zealand standards and the proposal of Rasmussen and Rondal to 7A04-T6 high-strength aluminium alloy CHS columns was evaluated through comparisons with the test and FE results. The results show that the European, Chinese and American standards provide conservative buckling resistance predictions, while the Australian & New Zealand standard and Rasmussen’s proposal generally yield
unsafe capacity predictions. Finally, two flexural buckling curves within the framework of the EN 1999-1-1:2007 design method, featuring a revised linear imperfection term and a newly developed hybrid linear-nonlinear imperfection term, were proposed accordingly, and were shown to provide more accurate and consistent buckling resistance predictions.
