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This paper studies the structural performance of cold-formed steel (CFS) face-to-face (FTF) built-up channel sections subjected to axial compression at high temperatures. The material properties of G250 and G450 CFS channel sections at room and high temperatures were acquired from the literature, and the range of temperatures was from 20 to 700 °C. The influences of the section thickness, member length, screw number, and high temperature on the structural performance of such channel sections were examined via a comprehensive parametric analysis involving 576 validated finite element models. As the temperature increased from 20 to 700 °C, the mean axial capacity of the CFS-FTF built-up unlipped and lipped channel sections decreased by 88.9% and 90.2%, respectively. Based on the results of the parametric study, new design equations for the axial capacity of CFS-FTF built-up channel sections at high temperatures were proposed. The mean ratio of the EWM strengths calculated using the American standard (AISI 2016) and Australian/New Zealand standard (AS/NZS 2018) to the FE strengths was 0.77, while the mean ratio of the proposed design strengths to the FE strengths was 1.01. Finally, a reliability analysis was conducted, and it was found that the proposed equations could come close in predicting the axial capacity of CFS-FTF built-up channel sections at high temperatures. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) is a popular form of construction in New Zealand and the developed world because it can be cost-effective, durable, sustainable, resilient to extreme environmental and seismic loads and easy to install. When used in domestic and medium-rise buildings, T-Stub connection between CFS channel sections is formed by using self-drilling screws which connect the flanges. In the literature, no prior investigation on the tension capacity of such connection has been reported. Therefore, this paper describes a novel test procedure for determining the tension capacity of such CFS T-Stub connection and the associated mechanism of failure. An experimental test program that comprises thirty experimental tests is reported in this paper. Three channel section thicknesses were examined: 0.55 mm, 0.75 mm, and 0.95 mm. All specimens failed as a result of tilting of the screws and bearing failure. Non-linear elasto-plastic finite element (FE) models were developed, and the predictions were validated against the experimental test results. It was adjudged that there was reasonable agreement in terms of connection strength and failure mode prediction. Finally, the design strengths derived from current design standards were compared with the experimental failure loads. It was found that the American Iron and Steel Institute (AISI 2016) and Australian and New Zealand Standard (AS/NZS 2018) are conservative by 6% and unconservative by 10% for the initial and final failure loads of T-Stub CFS connections, respectively. • A novel cold-formed steel T-stub connection was studied experimentally and numerically. • The results of a total of 30 new experimental tests were reported. • Finite element analysis was conducted and validated against the test results. • The prediction accuracy of current design standards was evaluated. [ABSTRACT FROM AUTHOR]

Aluminium alloy has recently become popular in New Zealand's construction sector as a sustainable building material. However, in roll-formed aluminium alloy (RFA) channel beams, particularly those having web holes, cripples at points of concentrated or localised loading. In this paper, end-two-flange (ETF) web crippling behaviour of RFA unlipped channels having web holes was investigated using experimental tests, numerical simulations and a deep learning model referred as deep belief network (DBN). A total of 1080 data points was generated to train the DBN, using a finite element (FE) model that was validated using 30 new experimental results reported in this paper. Compared to the test data, the DBN predictions were conservative by around 6%. Using the DBN predictions, a comprehensive parametric study was undertaken which used the validated FE model in order to explore the effects of hole size, hole location, section thickness, and bearing plate on the web crippling strength of RFA channels having web holes. Web crippling strengths obtained from the DBN, tests and finite element analysis (FEA) were utilised to evaluate the performance of current design specifications from the American Iron and Steel Institute (AISI), Australian/New Zealand Standards (AS/NZS 1664; AS/NZS 4600:2018) and Eurocode (CEN 2006, 2007). It is shown that the current design rules are not reliable to predict the web crippling strength of RFA unlipped channels with web holes. As a consequence of the parametric analysis, new web crippling strength and web crippling strength reduction factor formulae for perforated RFA unlipped channels were proposed. A reliability analysis was then conducted, which confirmed that the proposed equations are capable of predicting the ETF web crippling strength of perforated RFA unlipped channels. • ETF web crippling behaviour of roll-formed aluminium alloy channels was studied experimentally and numerically. • Finite element analysis was conducted and validated against test results. • A deep-learning model was developed to predict the web crippling strength. • A parametric study was conducted to investigate the effects of different parameters. • New design equations were proposed for web crippling strength of roll-formed aluminium alloy channels. [ABSTRACT FROM AUTHOR]

This paper investigates the interior-one-flange web crippling strength of cold-formed steel channels at elevated temperatures. The stress-strain curves of G250 and G450 grade cold-formed steel (CFS) channels at ambient and elevated temperatures were taken from the literature and the temperatures were varied from 20 to 700 °C. A detailed parametric analysis comprising 3474 validated finite element models was undertaken to investigate the effects of web holes and bearing length on the web crippling behavior of these channels at elevated temperatures. From the parametric study results, it was found that the web crippling strength reduction factor is sensitive to the changes of the hole size, hole location, and the bearing length, with the parameters of hole size and hole location having the largest effect on the web crippling reduction factor. However, the web crippling strength reduction factor remains stable when the temperature is changed from 20 to 700 °C. Based on the parametric analysis results, the web crippling strength reduction factors for both ambient and elevated temperatures are proposed, which outperformed the equations available in the literature and in the design guidelines of American standard (AISI S100-16) and Australian/New Zealand standard (AS/NZS 4600:2018) for ambient temperatures. Then, a reliability analysis was conducted, the results of which showed that the proposed design equations could closely predict the reduced web crippling strength of CFS channel sections under interior-one-flange loading conditions at elevated temperatures. [ABSTRACT FROM AUTHOR]

• The web crippling behaviour of cold-formed steel channel section having elongated edge-stiffened web holes under interior-two-flange loading condition was studied numerically. • The results of a total of 1,227 new finite element analysis were reported. • Design formulae for the web crippling strength reduction factor were suggested. • A direct strength method (DSM) equation was also presented to evaluate web crippling strength. In the past decade, cold-formed steel (CFS) channel sections having circular edge-stiffened web holes have been developed in New Zealand. Such edge-stiffened holes increase the strength of the CFS channel sections, compared to an equivalent section having unstiffened holes, while still allowing full service integration. In the case of web crippling, previous research has found that use of edge-stiffened holes almost results in the same strength of an equivalent channel-section having a plain web. Such circular edge-stiffened web holes can now be extended to elongated edge-stiffened web holes. However, for such elongated holes, no experimental tests have been reported in the literature. In this paper, a numerical investigation was carried out, and non-linear finite element (FE) analyses were used to investigate the web crippling behaviour of CFS channel sections having edge-stiffened web holes under the interior-two-flange (ITF) loading condition. The cases of both flange fastened and flange unfastened were considered. The FE models were validated against test results of sections having circular edge-stiffened web holes; good agreement in terms of the load–displacement curves and deformed shapes was shown. Using the validated FE models, a parametric study was carried out on CFS channel sections having elongated un-stiffened and edge-stiffened web holes, comprising 1,227 finite element analyses (FEA) results. Compared to sections having a plain web, for the case of an elongated opening, without any edge-stiffener, having an aspect ratio of two and three, the average reduction in web crippling strength was 39% and 49%, respectively. However, for an edge-stiffened hole, the reduction in the web crippling strength was reduced to only 2% and 16%, respectively. Finally, the 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 sections with elongated web holes were proposed. [ABSTRACT FROM AUTHOR]

• The structural behaviour of cold-formed steel T -stub connections with HRC and screws was studied experimentally and numerically. • The results of a total of 15 new experimental tests were reported. • Finite element analysis was conducted and validated against the test results. • The prediction accuracy of current design standards was evaluated. Cold-formed steel (CFS) T -Stub connections are widely used in single-story buildings, and their use is increasing in multi-story and long-span buildings. Recently, an innovative CFS T -Stub connection was developed using self-drilling screws and the Howick Rivet Connector (HRC), and such a newly-developed connection demonstrated excellent structural performance in the building industry. In this paper, a comprehensive experimental and numerical investigation was conducted to investigate the failure mechanism and structural behaviour of CFS T -Stub connections with a combination of HRC and screws under tension force, considering the effects of screw numbers. Firstly, a total of 15 new experimental tests were conducted on the CFS T -Stub connections with various numbers of screws. From the experiments, it was observed that the HRC was subjected to shear failures, while screws failed primarily due to tilting and bearing failures in all investigated specimens. Then, a non-linear elasto-plastic finite element (FE) model was developed and validated against the experimental results in terms of connection strength and failure modes. Finally, the design strengths obtained from the American Iron and Steel Institute (AISI 2016) & Australia/New Zealand standards (AS/NZS 2018) and Ahmadi et al. (2016) were compared with the test and FEA results, showing that the ultimate design strength of CFS T -Stub connections was overestimated by 16% and 14%, respectively. However, for T -Stub connections with HRC alone and with HRC and one screw, these design guidelines were unconservative by 5%. [ABSTRACT FROM AUTHOR]

The strength and stiffness of cold-formed steel portal frames are heavily related to the performance of their joints; these joints are normally formed through brackets, bolted to the webs of channels. They should have adequate strength to ensure the frame fails within the members, and the design moment capacity of a joint should be equal to or exceed the moment to which the joint is subjected. For apex brackets, based on the results of a non-linear elasto-plastic finite element study, the authors have recently proposed design guidance in the form of equations for predicting the moment capacity. However, this prediction was limited to fully restrained apex joints against lateral torsional buckling, which is an arrangement not commonly used in practice. Furthermore, the joints considered were composed of back-to-back brackets connecting back-to-back channels. The design recommendations were further limited to apex joints under bearing gravity load, equivalent to the opening moment applied to the bracket. This paper extends the previous work by now considering both single and double apex brackets, which are partially restrained, consistent with New Zealand practice, and considering both opening and closing moments on apex joints (or gravity and wind uplift load on portal frames). This study proposes unified design equations from a parametric study comprising 5,040 finite element models. • Validate finite element model of apex joints under bearing pure bending moment. • Propose design equations to predict the moment capacity of both the single and double apex brackets, used in practice. • Validate the proposed equation against the finite element analysis results of the practical portal frames. [ABSTRACT FROM AUTHOR]

The use of cold-formed steel (CFS) channels with web holes are becoming increasingly popular. Such holes, however, result in sections becoming more susceptible to lower axial compressive resistance. Traditional holes are normally punched at the web and un-stiffened. Recently, a new generation of CFS channels with edge-stiffened holes has been developed by the CFS industry but no information is available in the literature to accurately predict the axial capacity of such sections. The current design guidelines in accordance with the American Iron and Steel Institute (AISI 2016) and Australia New Zealand standards (AS/NZ 4600:2018) do not provide any design rules for CFS channels with edge-stiffened holes. In this paper, a numerical model that accurately simulated results from the experimental testing of CFS channels with edge-stiffened holes under axial compression as published in a previous paper by the authors was employed to carry out a parametric study which involved 348 finite element (FE) models. Variables which were examined included column slenderness, stiffener length, fillet radius, hole size, hole location and hole spacing. A comparison of the numerical results with current design rules for CFS channels with un-stiffened holes revealed that the design equations were not accurate for such sections; design equations are therefore proposed in which an enhancement factor is applied to the original equations. The enhancement factor was obtained using bivariate linear regression analysis. The proposed design equations closely predict the enhanced axial capacity of CFS channels with edge-stiffened holes. • A new generation of CFS channels with edge-stiffened holes was studied through finite element analysis • The FE model was validated against the previously published data for CFS channels with edge-stiffened holes • A parametric study which involved 348 FE models was conducted. • Variables are slenderness, stiffener length, fillet radius, hole size, hole location and hole spacing. • The developed design equations could predict the capacity of CFS channels with edge-stiffened holes. [ABSTRACT FROM AUTHOR]

Cold-Formed Steel (CFS) members are highly susceptible to several structural instability phenomena, involving either individual (Local — L, Distortional — D and Global — G) or interaction (LD, LG, DG, and LDG) buckling modes. The buckling mode interaction of CFS columns and beams may lead to strength erosion compared to isolated modes and must be considered in structural design. The North American, Australian/New Zealand and Brazilian standards incorporated the Direct Strength Method (DSM) that provides accurate design approach for columns and beams affected by L, D, G, and LG buckling modes. However, the coupled LD, DG, and LDG buckling modes are not currently considered in the DSM and many recent research projects have been focused on these topics. The procedure adopted by DSM estimates the CFS member strength through experimentally calibrated design strength equations and curves, based on the relationship between the member elastic stability and the steel yielding property, respectively the elastic critical buckling load and the plastic load, represented by the slenderness factor. The more accurate the buckling load, the more improved will be the result of the column strength by the DSM equations. In this context, the present paper presents the main results of the investigation, based on both experimental and finite element method numerical results, that conducted to calibrated strength curves for CFS unstiffened sections columns without holes covering LD interaction buckling mode. To take into account the effect of the LD buckling, the proposed procedure for design purposes incorporates the slenderness factor ratio R λ D L = λ D / λ L as the main variable, and λ L , λ D , λ G as the local, distortional and global slenderness factors, respectively. • Local–Distortional buckling mode interaction of thin-walled steel cold-formed columns. • General method for the design of columns under Local–Distortional buckling mode. • Structural design rules according to the Direct Strength Method principles. • Shell finite element method model for the analysis of steel thin-walled columns. [ABSTRACT FROM AUTHOR]

On 22 February 2011, one of the main structural walls of one of the tallest buildings in Christchurch, New Zealand (Grand Chancellor Hotel), had an extremely brittle and unusual failure that significantly damaged the building, severely compromising its structural stability. To this date, this peculiar failure mode has not yet been fully investigated and understood. Moreover, currently, it is not possible to identify and assess walls that are prone to this failure mode. Following recent findings based on experimental investigations, this failure mode was identified as out‐of‐plane shear‐axial failure. A Finite Element (FE) model was developed in DIANA to capture this failure mode, and through a numerical parametric study, the key parameters that contribute to the development of this failure mode in rectangular reinforced concrete (RC) walls were identified. Solid elements were used for the concrete material and embedded truss elements for the steel reinforcement. Bar buckling was not included in this investigation due to the limitation of DIANA in implementing the bar buckling and Menegotto‐Pinto models together, among which the latter was found to be more influential on the behaviour of RC walls investigated in this study. Based on the numerical and experimental studies conducted, an analytical method is proposed to: (1) identify rectangular walls prone to out‐of‐plane shear‐axial failure as a first‐level check for both design and assessment purposes; and (2) determine the out‐of‐plane drift capacity of rectangular walls prone to out‐of‐plane shear‐axial failure. Design recommendations are provided for rectangular walls prone to out‐of‐plane shear‐axial failure. [ABSTRACT FROM AUTHOR]

A series of eccentric load tests on aluminum alloy columns with square and rectangular hollow sections, fabricated by extrusion using 7A04-T6 aluminum alloy, were conducted in this paper. The initial geometric imperfections were measured prior to compression tests to investigate their impact on ultimate strength. The relevant load–displacement and load–strain curves acquired from testing reacted to the buckling behavior of columns subjected to combined axial load and bending, and the failure modes observed included overall buckling and the combination of local and overall buckling. Finite element models were developed and validated in conjunction with the experimental conditions and results. Then, an expanded parametric study was performed to explore the effect of the stability performance for columns over a wide range of normalized slenderness ratios and load eccentricity ratios. The experimental and numerical results were compared to the design strength provided by the current Chinese code, European code, American specification, and the Australian/New Zealand standard, as well as optional design approaches, the direct strength method and continuous strength method. The comparisons revealed that the majority of the current design provisions and methods presented relatively conservative predictions of ultimate strength for 7A04-T6 aluminum alloy columns under combined loading. A formula based on the Chinese code was proposed, with several parameters modified, to more accurately predict the ultimate strength of 7A04-T6 aluminum alloy columns. • Measuring initial geometric imperfection of 7A04-T6 aluminum alloy column and performing eccentric compression test. • Establish and verify the finite element model of eccentric compression column. • Studying the effect of initial imperfection, normalized slenderness ratio, and eccentricity on bearing capacity. • Proposing a design formula. For calculating the stability load bearing capacity. [ABSTRACT FROM AUTHOR]

Currently, the assembled-type light steel (ATLS) modular house is increasingly used for apartments, schools, hotels, and other similar buildings with repetitive units, in which the non-symmetric cold-formed angular section is usually served as column in the module unit. However, the compressive behavior and design method of the non-symmetric cold-formed angular column remain unknown due to the complex edge. In this paper, a series of tests were conducted on the axial compressive behavior of the non-symmetric cold-formed angular column. A total of 12 specimens with complex edge were tested under monotonic axial compression. A special support was designed at the end of the column to apply the axial compression along different loading axes of the complex section. The failure mode and axial compressive capacity of the test specimens were revealed and discussed in detail. It indicated that the loading axis significantly influenced the failure mode and axial compressive capacity of the non-symmetric cold-formed angular column. Furthermore, a 3D finite element model was developed and validated against the test results to broaden the research. Lastly, given that the current design codes for steel structures, as used in Europe, Australia/New Zealand and North, the relevant codified design was utilized to evaluate the axial compressive capacity of unequal angular column with a double edge fold stiffener, based on the obtained test data. • Experiment on non-symmetric angular column with complex edge. • Twelve specimens were tested and axial compressive capacity was obtained. • Elaborated FEM was developed and validated based on the test results. • The relevant codified design was utilized to evaluate the test specimens. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) channel beams are an increasingly popular choice as load-carrying members in building structures. Such channel beams often include web holes for installation of services. Traditional web holes are normally punched and are un-stiffened. This can restrict the size and spacing of web holes. Recently, a new generation of CFS channel beams with edge-stiffened web holes has been developed and used widely in New Zealand. However, no experimental investigation has been reported in the literature for such channel beams under bending. In this paper, a total of 215 results comprising 16 four-point bending tests and 199 finite element analysis (FEA) are reported on the moment capacity of CFS channel beams with both edge-stiffened and un-stiffened web holes. For comparison, channel beams without web holes were also tested. For all specimens, initial imperfections were measured using a laser scanner. A nonlinear elasto-plastic finite element (FE) model was also developed, and the results showed good agreement with the test results. A parametric study was conducted using the validated FE model to investigate the effects of beam length, hole diameter, stiffener length and fillet radius on the moment capacity of CFS channel beams. It is shown that for the case of a channel beam with five edge-stiffened web holes, the moment capacity increased by as much as 14.5%, compared to that of a plain channel beam. For comparison, the same section with un-stiffened web holes had a 13.6% reduction in moment capacity, compared to that of a plain channel beam. Furthermore, the accuracy of current design guidelines in accordance with the American Iron and Steel Institute (AISI) and Australia/New Zealand (AS/NZ) standards were verified by comparing the tests and FEA results against the design strengths for moment capacity of CFS channel beams without web holes. On the other hand, for CFS channel beams with web holes, the moment capacity obtained from tests and FEA were compared against the moment capacity calculated from the design equations of Moen and Schafer. Upon comparison, it was found that the AISI and AS/NZS can closely predict the moment capacity of CFS channel beams without web holes. The Moen and Schafer design equations were found to be over-conservative by around 11% and 28% for moment capacity of CFS channel beams with un-stiffened and edge-stiffened web holes, respectively. • A new generation of cold formed steel channel beams with edge stiffened holes is examined. • Results from an experimental regime and elasto-plastic finite element are reported. • A parametric study involving 199 FE models was conducted. • Variables included beam length, hole size, stiffener lengths and stiffener fillet radius. • Edge stiffened hole-sections can outperform plain sections in terms of moment capacity. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) back-to-back channels are becoming a popular choice for use in load-carrying members in building structures. These built-up channels often include web holes for installation of services. Traditional web holes are un-stiffened, which can restrict the size and spacing of holes. Recently, a new generation of CFS channels with edge-stiffened holes has been developed and used widely in New Zealand. No research has been reported in the literature to investigate the axial strength of back-to-back channels with edge-stiffened holes. Experiments are required on back-to-back channels with edge-stiffened holes so to understand the effects of composite actions between the back-to-back channels on the axial strength of such channels. This paper presents a total of 162 new results comprising 27 axial compression tests and 135 finite element analysis (FEA) results on the axial strength of back-to-back channels with edge-stiffened holes, un-stiffened holes and plain webs. Prior to compression tests, initial geometric imperfections were measured using a laser scanner. Tensile coupon tests were also conducted to determine the material properties of both the flat and corner portions of the channels. The test results show that for the case of back-to-back channels with edge-stiffened holes, the axial strength increased by 6.6% on average, compared to a back-to-back plain channel. For comparison, the same section with un-stiffened holes had a 12.4% reduction on average in axial strength, compared to a back-to-back plain channel. A nonlinear elasto-plastic finite element (FE) model was then developed, and the results showed good agreement with the test results. The validated FE model was used to conduct a parametric study involving 135 FE models to investigate the effects of column slenderness, diameter of hole, screw spacing, stiffener lengths and stiffener fillet radius on the axial strength of such channels. Finally, the tests and parametric study results were compared against the design strengths calculated in accordance with the American Iron and Steel Institute (AISI) (2016) and Australian and New Zealand Standards (AS/NZS) (2018) for back-to-back plain channels and against the design equations of Moen and Schafer (2011) for back-to-back channels with un-stiffened holes. It was found that the AISI (2016) and AS/NZS (2018) are only 3% conservative to the test results. The Moen and Schafer equations (2008, 2009, 2011) are conservative by 21% on average for back-to-back channels with un-stiffened holes. Deformed shapes at failure from experiments and FEA. Unlabelled Image • A new generation of back-to-back CFS channels with edge-stiffened holes is examined. • Results from an experimental regime and elasto-plastic finite element are reported. • A parametric study involving 135 FE models was conducted. • Variables included column slenderness, hole size, screw spacing, stiffener lengths and stiffener fillet radius. • Edge stiffened hole-channels can outperform plain channels in terms of axial strength. [ABSTRACT FROM AUTHOR]

This paper describes an experimental and numerical investigation to study the flexural capacity of back-to-back gapped built-up cold-formed steel (CFS) channel sections under four-point bending. The gap between the back-to-back channels was formed through intermediate link-channels which were screwed to the webs of the back-to-back channels. A total of 90 results comprising 18 laboratory tests and 72 finite element (FE) analysis results are reported on the flexural capacity of back-to-back gapped built-up CFS channel sections under four-point bending. Three different types of channels were considered to form the built-up channels: plain channels, channels with one web stiffener and channels with two web stiffeners. Two different beam spans as 1000 mm and 2000 mm were tested. Initial geometric imperfections were also measured prior to bending tests for all test specimens. A nonlinear FE model was then developed, the results of which showed good agreement against the laboratory test results. Using the validated FE model, an extensive parametric study was conducted to investigate the effects of web stiffeners and link-channel spacing on the flexural capacity of such gapped built-up beams. It is shown that design in accordance with the American Iron and Steel Institute, AISI (2016) and Australia/New-Zealand standards, AS/NZS (2018) can be conservative by as much as 27%. The flexural capacity of back-to-back gapped built-up sections with two web stiffeners was increased by 10% on average, when compared to the capacity of gapped built-up beams with plain channel sections. • Eighteen laboratory tests are reported on the flexural capacity of back-to-back gapped built-up CFS channel sections under four-point bending. • Three different types of channels: plain channels, channels with one web stiffener and channels with two web stiffeners were used to for the gapped built-up beams. • A nonlinear FE model was then developed, which included initial imperfections and modeling of link-channels and fasteners. • An extensive parametric study was conducted to investigate the effects of web stiffeners and link-channel spacing on the flexural capacity of such gapped built-up beams. • It is shown that design in accordance with the AISI & AS/NZS can be conservative by as much as 27%. [ABSTRACT FROM AUTHOR]

Recently, a new generation of cold-formed steel (CFS) channel sections with edge-stiffened circular holes have been developed by industry in New Zealand. No previous research, however, has considered the web crippling strength of CFS channel sections with edge-stiffened circular web holes under the interior-two-flange (ITF) loading conditions. In this paper, a combination of experimental investigation and non-linear finite element analysis (FEA) are used to investigate the effect of edge-stiffened holes under ITF loading conditions; for comparison, channel sections without holes and with unstiffened holes are also considered. In total, 30 web crippling test results are reported. A non-linear finite element (FE) model is described, and the results were compared against the test results, which showed a good agreement in terms of both the web crippling strength and failure modes. The results indicate that the stiffened web holes can significantly improve the web crippling strength of CFS channel sections. Using the validated FE model, a parametric study was conducted which include 1116 FE analyses, covering the effect of different hole sizes, edge-stiffener lengths and fillet radii, length of the bearing plates and position of the holes in the web. From the results of the parametric study, design recommendations in the form of web crippling strength reduction factors are proposed, that are conservative to both the experimental and FE results. • Web crippling tests of cold-formed channel section with edge-stiffened web openings was conducted. • The results indicate that the stiffened holes can significantly improve the web crippling strength. • Non-linear finite element (FE) models were developed and validated against the test results. • A parametric study involving 1116 FE analyses was performed. • Design recommendations in the form of web crippling strength reduction factors were proposed. [ABSTRACT FROM AUTHOR]

This paper describes an investigation of web crippling behaviour of aluminium alloy plain and lipped channels with flanges restrained. A total of 340 data is presented that include 52 test results and 288 numerical results. A series of tests was conducted on plain and lipped channels fabricated by extrusion using 6063-T5 and 6061-T6 heat-treated aluminium alloys under end-two-flange (ETF) and interior-two-flange (ITF) loading conditions. The concentrate loads were applied by means of bearing plates. The flanges of the channels were either bolted (fastened) to one or two bearing plates. A finite element model was developed and verified against the experimental results. Geometric and material non-linearities were included in the finite element model. It was shown that the finite element model closely predicted the web crippling strengths and failure modes of the tested specimens with flanges restrained. Hence, the finite element model was used for an extensive parametric study of cross-section geometries, and the web slenderness value ranged from 24.0 to 207.3. The test results and the web crippling strengths predicted from the finite element analyses were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for aluminium structures. A unified web crippling equation with new coefficients for aluminium alloy channels with flanges restrained under ETF and ITF loading conditions is proposed in this study. Since two failure modes of web buckling and web yielding were also observed in the aluminium plain and lipped channels with flanges restrained, design rules of web crippling strengths are also proposed by considering the lesser of the web buckling strength and web yield strength. • Web crippling tests were conducted on aluminum alloy channels with flanges restrained. • A finite element model was developed for aluminium alloy channels undergoing web crippling. • The effect of flange-restrained condition on the web crippling strengths of aluminium alloy channels was examined. • The current web crippling design rules for aluminum structures were assessed. • Two web crippling design approaches are proposed for aluminium alloy channels with flanges restrained. [ABSTRACT FROM AUTHOR]

The use of cold-formed steel (CFS) channel sections are becoming popular as the load-carrying members in building structures, and such channel sections often include web openings for the ease of installation of services. Traditional web openings are normally punched, and are unstiffened which can restrict the size and spacing of web openings. Recently, a new generation of CFS channel sections with edge-stiffened web openings has been developed, and is widely used in New Zealand. However, no experimental investigation has been reported in the literature for such channel sections under compression. In this paper, a total of 75 results comprising 26 axial compression tests and 49 finite element analysis results are reported on the compression resistance of CFS channel sections with both edge-stiffened and unstiffened web openings. For comparison, channel sections without web openings were also tested. For all specimens, initial imperfections were measured using a laser scanner. A nonlinear elasto-plastic finite element model was also developed, and the results showed good agreement with the test results. A parametric study was conducted using the validated finite element model to investigate the effect of opening spacing and column length on compression resistance of channel sections. It is shown that for the case of a channel section having seven edge-stiffened web openings, the compression resistance increased by as much as 22%, compared to a plain channel section. For comparison, the same section having unstiffened web openings had a 20% reduction in compression resistance, compared to a plain channel section. • A new generation of cold formed steel sections with edge stiffened holes is examined. • Results from an experimental regime and elasto-plastic finite element are reported. • Local and overall imperfections are considered in FE models. • Edge stiffened hole-sections can outperform plain sections in terms of axial strength. • A parametric study demonstrating the effect of opening spacing and column length was conducted. [ABSTRACT FROM AUTHOR]