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This study investigates the web crippling performance of roll-formed aluminium-lipped channels (ALCs) made of 5052-H36 aluminium alloy. The influence of web perforations on the crippling resistance of webs subjected to Interior-One-Flange (IOF) loading was examined. Laboratory tests were conducted on ALCs with and without circular openings at the mid-depth of the web. Finite element (FE) models were then developed and validated against the experimental results, ensuring their accuracy. To explore the influence of various parameters on the web crippling resistance, a parametric study was carried out. The parameters considered in the study include opening diameter, section depth, inside bent radius, bearing length, and aluminium grade. Using the data obtained from the parametric study, a comprehensive assessment of the available design guidelines for cold-formed steel and stainless steel was performed. New equations in the form of reduction factors were developed to accurately predict the reduction in the web crippling strength, showing their applicability to predict the reduction in the web crippling resistance due to web openings and statistically verifying their reliability. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) has emerged as a prominent choice for structural components and sections in the construction industry. The primary focus of this Special Issue is to disseminate the latest innovative research on CFS sections, aiming to positively impact the structural design and analysis of steel infrastructure. Non-linear finite element analysis and advanced optimization algorithms play essential roles in investigating the performance of CFS sections and achieving optimization [[11]]. [Extracted from the article]

In recent years cold form stainless steels members are becoming the most popular and widely used structural steel member in the construction industry due to their notable corrosion resistance, recycling option, aesthetically pleasing, and the favourable material properties. However, web crippling behavior and the capacity of unlipped channel sections with non‐circular web openings (Square, rectangular and elliptical) has not been investigated sufficiently. Hence, a numerical analyses was undertaken to investigate the web crippling behavior and strength of cold‐form stainless steel unlipped channel beams with non‐circular web openings. Finite element models of cold‐form ferritic stainless steel unlipped channel with offset circular web openings were developed under the interior‐two‐flange (ITF) and external‐two‐flanges (ETF) loading conditions. They were validated with currently available web crippling test results and a detailed parametric study was undertaken to develop an extensive web crippling strength database. Numerical results showed that the currently available reduction factor equations of circular web opening are either conservative or unsafe to use for the non‐circular opening. Hence, numerical results were then used to develop a reduction factor to the web crippling capacities of cold‐formed stainless steel beams with the solid web. [ABSTRACT FROM AUTHOR]

Stainless steel is a high‐performance construction material that combines the strength and stiffness associated with ferrous alloys with the corrosion resistance derived principally from the high chromium content. Its unique combination of properties usually comes at a cost, which puts increased emphasis on ensuring that the material is utilized to the upmost in structural applications. Consequently, in the recent years, an increase in the use of stainless steel in the construction industry has been witnessed, more specifically in exposed architectural applications and where total life economics, durability, improved resistance to aggressive environment, etc. are prime deciding criteria. However, the shear behaviour and capacity of cold‐formed stainless steel beams has not been investigated adequately in the past. Hence, detailed finite element analyses (FEA) were undertaken to investigate the shear behaviour and strength of stainless steel lipped channel beams (LCBs). The developed finite element models were first validated using the shear test results. They were then used in a detailed parametric study to investigate the effects of various influential parameters such as section thickness, depth and grade. Moreover, a parametric study was conducted to emphasize the beneficial effect of strain hardening of stainless steel on shear capacity of LCBs, in particularly for compact sections. FEA results showed that currently available design equations (EN1993‐1‐4) are inadequate to capture the available inelastic reserve capacity of compact stainless steel LCBs, thus suitable equations were proposed to enhance the predictions. This paper presents the details of finite element modelling and analyses of stainless steel LCBs and the development of these new shear design rules. [ABSTRACT FROM AUTHOR]

In the recent years, an increase in the use of stainless steel in the construction industry has been witnessed, more specifically in exposed architectural applications and where total life economics, durability, improved resistance to aggressive environment etc. are prime deciding criteria. However, limited research has been undertaken on the shear behaviour and strength of cold‐formed stainless steel beam with web openings. Hence a numerical study was undertaken to investigate the shear behaviour and strength of cold‐formed stainless steel with web openings. Finite element models of simply supported cold‐formed stainless steel Lipped Channel Beams with web openings were developed under a mid‐span load. They were then validated with currently available shear test results and further used in a detailed parametric study. In this research, both stocky and slender cross‐sections were considered. The ultimate shear capacities from finite element analyses confirmed that currently available design equations are inadequate to determine the shear capacities of stainless steel beams with web openings. Hence improved design equations were developed for the shear capacity of cold‐formed stainless steel beams with web openings. This paper presents the details of this numerical study of cold‐formed stainless steel beams with web openings, and the results.. [ABSTRACT FROM AUTHOR]

Cold‐formed steel (CFS) members, when subjected to optimisation, can significantly increase their ultimate load carrying capacity leading to a more economical and efficient structural system. This paper presents the details of an investigation on optimisation of CFS beams subjected to bending capacity and an investigation of shear and web crippling capacities of optimised sections. The optimisation was aimed to meet construction constraints reported in Eurocode 3 (EC3). In this research, 4 different CFS sections were considered including the introduction of 2 novel sections (Super Sigma and Smart Beam) which has closer shear center to the web and less susceptible to web buckling. The bending capacity of the available sections were obtained based on the effective width method reported in EC3, while the optimisation procedure was performed using particle swarm optimisation (PSO). The capacities of the optimised CFS beams were also obtained using the nonlinear finite element (FE) analysis and the FE results were compared with EC3. The FE results showed that the Smart beam and Super Sigma claim dual advantage of increase in section moment capacity and restrain against torsional effect than the conventional CFS channel sections with the same amount of material. These optimised cold formed steel beams can be employed in light gauge steel building constructions. [ABSTRACT FROM AUTHOR]

The application of aluminium alloy members in building construction has considerably increased in recent years due to their appealing advantages such as corrosion resistance and high strength-to-weight ratio. However, the elastic modulus of aluminium is only one-third of that of steel, making aluminium members being susceptible to various buckling modes including web crippling. To date, only a limited amount of research study has been conducted to investigate the web crippling failure phenomenon in aluminium structural members, and no research has been carried out on the web crippling behaviour of roll-formed aluminium lipped channel sections. Hence, an experimental study was conducted to assess the web crippling behaviour and capacities of unfastened aluminium lipped channel sections under two flange load cases (End-Two-Flange (ETF) and Interior-Two-Flange (ITF)). Forty tests were performed with different bearing lengths, web heights and thicknesses. The results obtained from this study were then compared with the nominal web crippling strengths predicted using the design rules provided by the Australian, European and American Standards. The comparison showed that the current design equations are potentially unsafe and unreliable to estimate the capacity for aluminium lipped channel sections under both ETF and ITF load cases. Hence, suitable modifications were proposed to the available design equations based on the experimental results to accurately predict the web crippling capacities of aluminium lipped channel sections. Generally, it is shown that the web crippling results acquired from the modified equations agreed well with the test results. • Experimentally investigated the web crippling capacities aluminium lipped channel sections. • Two flange load cases were considered while flanges were unfastened to the supports. • Current design equations are unsafe for rolled-formed aluminium lipped channel sections. • Unified design rules for aluminium and cold-formed steel lipped channel sections were proposed. • Improved design rules were also proposed based on Australian and European aluminium standards. [ABSTRACT FROM AUTHOR]

Cold-formed steel members have been widely used in residential and commercial buildings as primary load bearing structural elements. They are often made of thin steel sheets and hence they are more susceptible to local buckling. The buckling behaviour of cold-formed steel compression members under fire conditions is not fully investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken to investigate the local buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. First a series of 91 local buckling tests was conducted at ambient and uniform elevated temperatures up to 700 °C on cold-formed lipped and unlipped channels. Suitable finite element models were then developed to simulate the behaviour of tested columns and were validated using test results. All the ultimate load capacity results for local buckling were compared with the predictions from the available design rules based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Parts 1.2 and 1.3 and the direct strength method (DSM), based on which suitable recommendations have been made for the fire design of cold-formed steel compression members subject to local buckling at uniform elevated temperatures. [ABSTRACT FROM AUTHOR]

Current design rules for the member capacities of cold-formed steel columns are based on the same non-dimensional strength curve for both fixed and pinned-ended columns at ambient temperature. This research has investigated the accuracy of using current ambient temperature design rules in Australia/New Zealand (AS/NZS 4600), American (AISI S100) and European (Eurocode 3 Part 1.3) standards in determining the flexural–torsional buckling capacities of cold-formed steel columns at uniform elevated temperatures using appropriately reduced mechanical properties. It was found that these design rules accurately predicted the member capacities of pin ended lipped channel columns undergoing flexural torsional buckling at elevated temperatures. However, for fixed ended columns with warping fixity undergoing flexural–torsional buckling, the current design rules significantly underestimated the column capacities as they disregard the beneficial effect of warping fixity. This paper has therefore recommended the use of improved design rules developed for ambient temperature conditions to predict the axial compression capacities of fixed ended columns subject to flexural–torsional buckling at elevated temperatures within AS/NZS 4600 and AISI S100 design provisions. The accuracy of the proposed fire design rules was verified using finite element analysis and test results of cold-formed lipped channel columns at elevated temperatures except for low strength steel columns with intermediate slenderness whose behaviour was influenced by the increased nonlinearity in the stress–strain curves at elevated temperatures. Further research is required to include these effects within AS/NZS 4600 and AISI S100 design rules. However, Eurocode 3 Part 1.3 design rules can be used for this purpose by using suitable buckling curves as recommended in this paper. [ABSTRACT FROM AUTHOR]

Cold-formed steel members are widely used in residential, industrial and commercial buildings as primary load-bearing elements. During fire events, they will be exposed to elevated temperatures. If the general appearance of the structure is satisfactory after a fire event then the question that has to be answered is how the load bearing capacity of cold-formed steel members in these buildings has been affected. Hence after such fire events there is a need to evaluate the residual strength of these members. However, the post-fire behaviour of cold-formed steel members has not been investigated in the past. This means conservative decisions are likely to be made in relation to fire exposed cold-formed steel buildings. Therefore an experimental study was undertaken to investigate the post-fire mechanical properties of cold-formed steels. Tensile coupons taken from cold-formed steel sheets of three different steel grades and thicknesses were exposed to different elevated temperatures up to 800 °C, and were then allowed to cool down to ambient temperature before they were tested to failure. Tensile coupon tests were conducted to obtain their post-fire stress–strain curves and associated mechanical properties (yield stress, Young׳s modulus, ultimate strength and ductility). It was found that the post-fire mechanical properties of cold-formed steels are reduced below the original ambient temperature mechanical properties if they had been exposed to temperatures exceeding 300 °C. Hence a new set of equations is proposed to predict the post-fire mechanical properties of cold-formed steels. Such post-fire mechanical property assessments allow structural and fire engineers to make an accurate prediction of the safety of fire exposed cold-formed steel buildings. This paper presents the details of this experimental study and the results of post-fire mechanical properties of cold-formed steels. It also includes the results of a post-fire evaluation of cold-formed steel walls. [ABSTRACT FROM AUTHOR]

Experimental and numerical investigations were conducted in this study to explore the structural behaviour and design of Aluminium Lipped Channel (ALC) beams subjected to combined bending and shear actions. Finite element models were developed and validated using test results. The ultimate strength results obtained from the tests and parametric study were compared with those estimated using current design rules. It was found that the current design rules are too conservative to predict the ultimate capacities of ALC beams subjected to combined bending and shear. Hence new design equations were proposed in this study to accurately predict these ultimate capacities. • Investigated the structural behaviour of ALC beams under combined bending and shear actions. • Experimental studies were conducted for bending and combined actions. • Numerical studies were conducted for shear, bending and combined actions. • Current cold-formed steel design rules were not suitable for ALC beams under combined actions. • New design rules were proposed for ALC beams under combined actions. [ABSTRACT FROM AUTHOR]

Abstract: This paper has presented the details of an investigation into the flexural and flexural–fl buckling behaviour of cold-formed structural steel columns with pinned and fixed ends. Current design rules for the member capacities of cold-formed steel columns are based on the same non-dimensional strength curve for both fixed and pinned-ended columns. This research has reviewed the accuracy of the current design rules in AS/NZS 4600 and the North American Specification in determining the member capacities of cold-formed steel columns using the results from detailed finite element analyses and an experimental study of lipped channel columns. It was found that the current Australian and American design rules accurately predicted the member capacities of pin ended lipped channel columns undergoing flexural and flexural torsional buckling. However, for fixed ended columns with warping fixity undergoing flexural–torsional buckling, it was found that the current design rules significantly underestimated the column capacities as they disregard the beneficial effect of warping fixity. This paper has therefore proposed improved design rules and verified their accuracy using finite element analysis and test results of cold-formed lipped channel columns made of three cross-sections and five different steel grades and thicknesses. [Copyright &y& Elsevier]

Highlights: [•] Developed finite element models of load bearing LSF walls under standard fire. [•] Validated models using 11 LSF wall fire tests with various configurations. [•] Models included thermal bowing, local buckling and neutral axis shift of wall studs. [•] Provided useful load ratio versus time curves to predict fire rating of LSF walls. [•] Confirmed the superior fire performance of externally insulated wall panels. [Copyright &y& Elsevier]

Abstract: Traditionally the fire resistance rating of LSF wall systems is based on approximate prescriptive methods developed using limited fire tests. Therefore a detailed research study into the performance of load bearing LSF wall systems under standard fire conditions was undertaken to develop improved fire design rules. It used the extensive fire performance results of eight different LSF wall systems from a series of full scale fire tests and numerical studies for this purpose. The use of previous fire design rules developed for LSF walls subjected to non-uniform elevated temperature distributions based on AISI design manual and Eurocode3 Parts 1.2 and 1.3 was investigated first. New simplified fire design rules based on AS/NZS 4600, North American Specification and Eurocode 3 Part 1.3 were then proposed in this study with suitable allowances for the interaction effects of compression and bending actions. The importance of considering thermal bowing, magnified thermal bowing and neutral axis shift in the fire design was also investigated. A spread sheet based design tool was developed based on the new design rules to predict the failure load ratio versus time and temperature curves for varying LSF wall configurations. The accuracy of the proposed design rules was verified using the test and FEA results for different wall configurations, steel grades, thicknesses and load ratios. This paper presents the details and results of this study including the improved fire design rules for predicting the load capacity of LSF wall studs and the failure times of LSF walls under standard fire conditions. [Copyright &y& Elsevier]

Abstract: Light Gauge Steel Framing (LSF) walls made of cold-formed and thin-walled steel lipped channel studs with plasterboard linings on both sides are commonly used in commercial, industrial and residential buildings. However, there is limited data about their structural and thermal performance under fire conditions while past research showed contradicting results about the benefits of using cavity insulation. A new composite wall panel was recently proposed to improve the fire resistance rating of LSF walls, where an insulation layer was used externally between the plasterboards on both sides of the wall frame instead of using it in the cavity. In this research 11 full scale tests were conducted on conventional load bearing steel stud walls with and without cavity insulation, and the new composite panel system to study their thermal and structural performance under standard fire conditions. These tests showed that the use of cavity insulation led to inferior fire performance of walls, and provided supporting research data. They demonstrated that the use of insulation externally in a composite panel enhanced the thermal and structural performance of LSF walls and increased their fire resistance rating. This paper presents the details of the LSF wall tests and the thermal and structural performance data and fire resistance rating of load-bearing wall assemblies lined with varying plasterboard-insulation configurations under two different load ratios. Fire test results including the time–temperature and deflection profiles are presented along with the failure times and modes. [Copyright &y& Elsevier]

Aluminium lipped channel (ALC) beams in the construction industry are becoming more popular due to their unique mechanical characteristics of durability and high strength-to-weight ratio. However, the elastic modulus of aluminium is only one third that of steel. Hence the ALC beams can buckle easily under shear, web crippling and bending actions. In the past, the structural behaviour of ALC beams under shear, web crippling and bending actions was investigated in isolation. For practical applications, however, the structural behaviour of ALC beams under combined actions should be investigated so that rational design rules can be developed. Recently, a research study was conducted at Griffith University to investigate the structural behaviour and design of ALC beams subjected to combined bending and shear actions. In the current study, an experimental program was conducted focussing on the structural behaviour and design of ALC beams subjected to combined bending and web crippling actions. Specifically, a series of tests was performed at Griffith University using ALC beams to investigate the behaviour and strengths of such sections subjected to combined bending and web crippling under unfastened interior one flange (IOF) loading conditions. Different interaction factors were selected to study the interaction levels of the bending moment and web crippling strengths of ALC beams. The length of ALC specimens in combined actions is non-dimensionalised based on the ultimate capacities of such beams subjected to pure bending and pure web crippling. The results from the combined bending and web crippling tests were then compared with the current design rules of AS/NZS 4600, AISI S100, and Eurocode 3 Part 1.3 based on the linear interaction equations, to verify their accuracy in predicting the capacities of ALC beams under combined bending and web crippling actions. • Experimentally investigated the strength and behaviour of roll-formed ALC beams under combined bending and web crippling actions. • ALC sections with different web slenderness, bearing lengths, and interaction factors were considered. • It was found that there are no aluminium design rules to predict the strengths of roll-formed ALC beams under combined actions. • Hence the test results were compared with the current Australian, American and European cold-formed steel design rules to verify their accuracy in predicting the strengths. • The design rules in Eurocode 3 Part 1.3 were found to be conservatively predicting the strengths of ALC beams subjected to combined actions. [ABSTRACT FROM AUTHOR]

A sub-head refers to the horizontal member at the top of an aluminium window wall system. Under wind load, bearing failure of the aluminium sub-head (ASH) flange due to its long length is a common failure mode, being subjected to high concentrated load transferred from the vertical members (mullions). The bearing behaviour of ASH sections was previously investigated experimentally by the authors and suitable equations (DRA I) were proposed to predict the bearing capacities. These design rules were manufacturer and product specific and only applicable for sections considered in the test plan. To address these limitations, the present study further investigates the behaviour and design of ASH sections through non-linear static analyses using ABAQUS, based on implicit integration schemes. The effects of mesh size, element type, and loading plates on the bearing behaviour of ASH section under different loading and boundary conditions was addressed. The finite element models were validated against the test results in terms of ultimate loads, load–displacement curves and failure modes, and the validated model was then used to perform an extensive parametric study. A broad range of ASH sections covering flange widths ranging from 40 to 100 mm, thicknesses varying between 2 and 4 mm, bearing widths ranging from 50 to 150 mm, and six engagement lengths (5 to 30 mm) was considered in the parametric study. It should be noted that the ultimate loads obtained from the parametric study are not product nor manufacturer specific. Since no aluminium design rules exist to predict the bearing capacities of ASH sections, the accuracy of the current cold-formed steel design rules (DRSs) and that of DRA I were assessed. Both DRSs and DRA I were found not to be suitable for ASH sections in window walls, hence appropriate modifications were made in this study and the proposed design rules (DRA P) predicted accurate bearing capacities which agreed well with the numerical results. • Numerically investigated the bearing behaviour of aluminium sub-heads in façade systems. • Considered various section geometries, bearing widths, loading and boundary conditions. • The finite element models were validated against the previous test results and extensive parametric study were performed. • Current cold-formed steel design equations were not suitable for aluminium sub-heads in window walls. • New design rules were proposed for aluminium sub-heads based on the numerical results. [ABSTRACT FROM AUTHOR]

Aluminium members are recently being used as main structural elements in residential, commercial and industrial buildings. Aluminium Lipped Channel Beam (LCB) is one of the popular thin-walled sections used in different applications in construction. Web openings are incorporated in these sections to accommodate building services when they are used as beams. Even though the bending, shear and web crippling behaviours of these sections were investigated in the past, their structural behaviour with web openings have not been investigated. Hence, experimental and numerical studies were conducted in this research to investigate the shear behaviour of these aluminium LCBs with web openings. An aspect ratio of one was considered in this study. A total of 17 tests were conducted first to investigate the shear behaviour of aluminium LCBs with circular web openings using three-point loading arrangement. Finite element models were developed with appropriate loading and boundary conditions and validated using the experimental results. A detailed parametric study was then undertaken using the currently available roll-formed aluminium LCBs with different thicknesses, grades and web opening sizes. The ultimate shear capacities and the shear capacity reduction factors obtained from the tests and finite element analyses were compared with the currently available design rules. This paper presents the details and results of the experimental and numerical studies on the shear behaviour of aluminium LCBs with circular web openings and the comparison with current and recently proposed design rules. • Investigation of the shear behaviour of roll-formed aluminium lipped channel beams (LCBs) with web openings. • Both experimental and numerical studies were conducted with various section geometries, web opening sizes and aluminium grades. • Currently there are no design rules to predict the shear capacity reduction factors for aluminium sections with web openings. • The shear capacity reduction factor design rules proposed in the past for cold-formed steel LCBs were found to be suitable for aluminium LCBs. [ABSTRACT FROM AUTHOR]

In the building sector, the application of aluminium alloys in load carrying structures as well as building envelopes has received attention over the past decades. Under wind loading, the vertical members of window walls known as mullions, carry the horizontal load transferred from the glass panels. This load is then transferred to the sub-heads at the top and the sub-sills at the bottom which are connected to the structure. The aluminium sub-head flange due to its long length is susceptible to bending (bearing failure) under this loading condition, a phenomenon that has hitherto not been adequately researched. Hence the performance of aluminium sub-head sections subjected to bearing failure was investigated through a series of 42 tests. This study mainly explores the impacts of parameters such as the bearing width, the loading and boundary conditions, as well as various geometric sections, on the bearing failure of aluminium sub-heads. The significant failure modes observed in the tests were yielding at web-flange junction and slipping of the bearing plate. Currently, no design rules are available to predict the bearing capacity of aluminium sub-heads. Hence a comparison of the ultimate bearing capacities of the test results and the design capacities obtained using the available cold-formed steel design specifications was performed. The code-predicted design strengths were found to be overly conservative for aluminium sub-head sections in window walls. Therefore, new design equations were developed to ensure safe, economic and reliable design of aluminium sub-heads using a wide range of bearing capacity data obtained from the experimental studies. The proposed design rules were found to be in precise agreement with the experimental values. • Experimentally investigated the bearing behaviour of aluminium sub-heads in façade systems. • Considered various section geometries, bearing widths, bolt connections, loading and boundary conditions. • Sub-head sections failures were due to yielding of the web-flange junction and slipping of bearing plate. • Current cold-formed steel design equations are overly conservative for aluminium sub-heads. • New design rules were proposed for aluminum sub-heads and calibrated using test results. [ABSTRACT FROM AUTHOR]

Aluminium alloys have recently drawn significant attention in structural applications due to its outstanding mechanical characteristics. Thin-walled members fabricated by aluminium alloys can be more competitive in construction industries than the conventional cold-formed steel sections, particularly in areas with high humidity and severe environmental conditions. Nevertheless, they are more vulnerable to various types of instability due to their relatively low elastic modulus compared to steel. Applying high concentrated load transversely on thin-walled members can cause critical damage to the web of the cross section called web crippling. Although a large number of studies has been performed to investigate the web crippling mechanisms on different types of sections, the existing studies are primarily of the empirical nature and thus merits further investigations. To fill the research gap, this study was thus performed based on our previously conducted experimental work to further comprehend the web crippling phenomenon of the roll-formed aluminium lipped channel (ALC) sections under the loading conditions of end-two-flange (ETF) and interior-two-flange (ITF). This was done through numerical investigations followed by a parametric study which are reported herein in details. A wide range of roll-formed ALC sections covering web slenderness ratios ranged from 28 to 130, inside bent radii ranging between 2 mm and 8 mm, bearing lengths ranged from 50 mm to 150 mm, and three sheeting aluminium alloy grades (5052-H32, 5052-H36 and 5052-H38) were considered in the parametric study. The acquired web crippling database was then used to assess the consistency and accuracy of the current design rules used in practice. It was found that the web crippling capacity determined by the current international specifications are unsafe and unreliable, whereas the predictions of the recently proposed equations agree very well. Furthermore, a Direct Strength Method (DSM)-based capacity prediction approach was proposed and then validated against the web crippling database acquired here as well as the experimental and numerical data for cold-formed steel lipped channel sections used in the literature. • Investigated the web crippling capacities of unfastened aluminium lipped channel sections under two-flange load cases.. • Current design equations based on Australian and European aluminium standards were found to be unsafe. • Recently proposed design guidelines by authors were verified against wide-range of parametric data. • Increased length was proposed for Interior-two-flange (ITF) aluminium specimens for experimental and numerical studies. • Unified DSM-based approach was developed for both roll-formed aluminium and cold-formed steel lipped channel sections. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) beams are commonly deployed in construction with web holes to accommodate service conduits. The web holes are subjected to stiffening methods aiming to restore the load-carrying strength reduction. In the shear design of CFS channels with stiffened web holes, the elastic shear buckling strength is the basis for the design irrespective of the available post-buckling strength. Therefore, this paper investigates the elastic shear buckling characteristics of CFS channels with stiffened circular web holes, which is still unresearched. Numerical simulations were conducted using the Abaqus finite element analysis software to study the elastic shear buckling response. Parametric studies were then performed, where a data pool was generated for CFS channels with no web holes, unstiffened web holes, and stiffened web holes, covering a range of parameters including web slenderness, web hole size, corner radius and edge stiffening element length. It was shown that edge stiffening of the web hole improves the shear buckling capacity compared to the CFS channels with no web holes and unstiffened web holes. New unified design proposals to estimate the elastic shear buckling strength of CFS channels with no web holes, unstiffened web holes, and edge stiffened web holes were developed based on the generated data. The new unified design proposals of modified shear buckling coefficient and equivalent thickness method offer accurate elastic shear buckling strength predictions. • Performed elastic shear buckling analysis of channels with stiffened web holes. • Investigated the effect of stiffener length on the shear buckling strength. • Edge stiffeners improved the elastic shear buckling strength. • Proposed unified shear buckling coefficient and equivalent thickness method. • Introduced a normalised factor (ϕ) to reflect the influence of edge stiffener. [ABSTRACT FROM AUTHOR]

• Fiber-filled steel tubular posts and beams were manufactured. • The manufactured FFST columns were tested in compression. • The FFST beams were tested in three-point shear tests and four-point bending tests. • The manufactured FFST frame was analysed in three-point shear tests. • Results suggest that the proposed hybrid elements can be a potential alternative for CFST in terms of structural performance. In recent years, the building industry has shown great interest in hybrid-timber construction. A smart combination of timber, steel and concrete can produce building structures that not only have a less environmental impact and lower carbon footprint, but also bring lighter, taller (buckling-resilient), and long-spanning solutions. Moreover, efficient technologies can be used to rework or recycle wood products, such as fibres into hybrid modules to assist the growing trend towards a circular economy. In this study, small-scale hybrid steel-timber structural modules are developed by inserting dried wood fibre products inside cold-formed steel square hollow sections without using adhesive. Using this technique, fibre-filled steel tubular (FFST) beams, columns, and 2D frames were manufactured and tested. The experimental results indicate that the FFST columns have axial stiffness and strength by 44% and 55%, respectively, higher than steel-only columns, while the flexural stiffness and strength of the FFST beam are 8.5% and 28% higher, respectively than the steel-only beam. The weight-to-performance ratio for the FFST columns and beams is 19.03% and 58.82% higher than a steel-only columns and beams, respectively. The beam-to-column connections of the FFST frames showed sizeable ductility in flexure. The significant results as part of this paper, as well as ease of assembly, suggest that the proposed FFST frames can be up scaled and potentially be used in residential dwellings or similar low-rise applications. [ABSTRACT FROM AUTHOR]

Recent trends in the construction industry have sought to use cold-formed (CF) carbon steel, CF aluminium and CF stainless-steel as flexural members and in some instances as primary load-carrying members. Flexural members when subjected to concentrated loads undergo various failure modes, a major failure mode being web crippling. The large width-to-thickness ratios of these thin-walled beams makes them vulnerable to local buckling failure. Although there are four loading conditions to consider, this paper focuses on Interior-One-Flange (IOF) loading condition. Currently, individual design equations are available for determining the web crippling capacity of CF carbon steel, CF aluminium and CF stainless-steel under IOF loading. However, to-date there has been no attempt to produce a unified web crippling design equation. An all-encompassing numerical study focussed on the key web crippling parameters, both cross-sectional dimensions and mechanical properties and a unified grade, fy = 220 MPa, was achieved across the three structural materials to allow for a unified design equation. A total of 378 Finite Element (FE) models were obtained. It was found that AS/NZS 4600, AISI S100 and Eurocode 3 provided good agreement, but with a higher coefficient of variation (COV) values than recommended. Additionally, AS/NZS 1664.1 was found to be unsafe. CF carbon steel parametric study results validated existing equations, which were accurate and able to predict the web crippling capacity under IOF loading. However, unified web crippling design equation was modified which can improve the accuracy when predicting the web crippling capacity of CF aluminium and CF stainless-steel lipped channel sections (LCBs) under IOF loading conditions. The unified equation was supplemented by web crippling coefficients specific to each of the structural materials. • Web crippling behaviour of lipped channel section was investigated for cold-formed carbon, aluminium and stainless steel • Finite element models using Abaqus were generated and validated with IOF experimental data set • Parametric study was conducted for three materials: cold-formed carbon steel, aluminium and stainless steel • Proposed coefficients to unified web crippling design equation considering yield strength and elastic modulus factors • Accuracy of the proposed equations for all three materials were calculated and listed [ABSTRACT FROM AUTHOR]

This paper focuses on the web crippling performance of staggered slotted perforated Cold-Formed Steel (CFS) channels under Interior-One-Flange (IOF) load case, highlights the web crippling strength reduction, and provides reliable design guidelines. Finite Element (FE) analysis was employed to represent the IOF load case web crippling behaviour of staggered slotted perforated CFS channels. The developed FE models were then validated against laboratory tests on web crippling of CFS channels with both solid web and web openings under IOF load case. A parametric study (288 models) was conducted using the validated models to assess the effect of staggered slotted configurations and the corresponding degree of reduction in web crippling strength. It is shown that staggered slotted perforations play an important role in defining performance and may lead to a considerable reduction (up to 49%) in web crippling strength. Based on the results of the parametric study, new web crippling design equations were developed for IOF load case accounting the staggered slotted perforations. The web crippling strength predictions using the proposed equations yielded at a much higher level of accuracy, enhancing the commercial aspects of slotted perforated channels. [Display omitted] • Investigated the web crippling behaviour of CFS beams with staggered slotted perforations under IOF loading. • Non-linear finite element models were developed and validated against web crippling test results. • Parametric finite element analyses were undertaken considering all key influencing parameters. • Staggered slotted perforations reduced the web crippling strength with a maximum reduction value of 49%. • A new web crippling design approach was developed to capture the effect of staggered slotted perforations. [ABSTRACT FROM AUTHOR]

Cold-Formed (CF) structural members have recently drawn significant attention in light gauge steel construction. The employment of the different materials, for example CF carbon steel, stainless steel and aluminium, are becoming more common. These structural members are often subjected to concentrated loading conditions, which ultimately leads to failure through web crippling. A plethora of experimental and numerical studies have investigated the web crippling strength and behaviour of CF carbon steel lipped channel sections. However, only limited studies are available for CF stainless steel and aluminium members. This paper presents the investigation of the web crippling strength of CF lipped channel beams under End Two Flange (ETF) loadings and aims to propose a unified equation considering strength factor. Finite Element (FE) models of CF carbon steel, aluminium, and stainless steel lipped channel beams were developed and validated against the available web crippling ETF load case experimental data. Subsequently, a detailed parametric study was performed based on the validated FE models, to establish a wide-ranging data set. New ETF load case web crippling unified design guidelines were proposed for the CF lipped sections made of carbon steel, stainless steel, and aluminium. Unlabelled Image • Investigated the ETF load case web crippling of cold-formed carbon steel, stainless steel, and aluminium lipped channels. • A suitable finite element models were developed and validated with test results. • The parametric analysis included 189 FE models and three common yield strengths were considered. • Proposed unified design equation for three different materials considering strength factors. • The proposed equation showed a good accuracy with parametric finite element results. [ABSTRACT FROM AUTHOR]

Providing staggered slotted perforations to the Cold-Formed Steel (CFS) beams is a new approach being used in light gauge steel construction aiming to enhance both the fire and energy performances. However, slots in the web reduce the load-bearing capacity of CFS beams and existing studies do not provide a definite evaluation of the design expressions to determine the structural performance of slotted perforated CFS flexural members. Therefore, the present study aims to establish a methodology to determine the flexural capacity of staggered slotted perforated CFS beams subject to local buckling through developing three-dimensional Finite Element (FE) models. The developed FE models were subjected to validation against the related test data. Subsequently, the validated FE model was employed to conduct further parametric studies (432 FE models). Parameters include the dimensions of the CFS beams and staggered slotted perforations, rows and row groups of slots and yield strength. The effect of these factors on the local buckling capacity of the staggered slotted perforated CFS beams under bending is discussed. The paper concludes with a proposal of Direct Strength Method (DSM) based new design equations to predict the bending capacity of the CFS beams with staggered slotted perforations subject to local buckling and to enhance their commercial aspects. • Investigated the local buckling behaviour of CFS beams with staggered slotted perforations. • Suitable non-linear finite element models were developed and calibrated using test data. • Extensive finite element parametric analyses were undertaken considering all the influencing parameters. • Staggered slotted perforations reduced the local buckling flexural capacity with a maximum reduction value of 11%. • The current DSM was extended for the design of staggered slotted perforated CFS beams subject to local buckling. [ABSTRACT FROM AUTHOR]

Cold-Formed Steel (CFS) members with slotted perforations in webs are used in civil construction to amplify the thermal and energy performance of structures. However, the slotted webs reduce the structural performance of the element, prominently their shear, bending and combined bending and shear strengths. Many research studies have been undertaken to examine the behaviour of CFS channel sections subject to bending. Yet, no research has been performed to investigate the distortional buckling behaviour of slotted perforated CFS flexural members. Finite Element (FE) models of CFS channels with staggered slotted perforations were developed herein to investigate their distortional buckling under bending stress. A parametric study was conducted in detail by developing 432 slotted perforated CFS FE models based on the validation process with available experimental results. In particular, this paper presents the FE analysis details of CFS flexural members with slotted perforations subject to distortional buckling and results. The reliability of the current Direct Strength Method (DSM) for CFS flexural members with web holes subject to distortional buckling in accordance with the North American Specification (AISI S100) (2016) and the Australian/New Zealand Standards (AS/NZ 4600) (2018) was investigated. Modified DSM formulae for slotted perforated CFS flexural members subject to distortional buckling were also proposed. • Distortional buckling behavior of CFS beams with staggered slotted perforations have been investigated. • Finite element models showed good agreement with available test data. • All influencing parameters were considered in the parametric studies. • Staggered slotted perforations reduced the distortional buckling flexural capacity up to 23%. • New direct strength method based design equations were proposed for distortional buckling. [ABSTRACT FROM AUTHOR]