Cold-formed Steel Sections Research Articles

Comparison study on cold formed steel of coupled channel section based on abaqus and cufsm by simple-simple end condition

Cold formed steel (CFS) channel sections are the sections which are widely using from last few decades and are designated as light gauge sections. Such sections are being widely utilized in industrial, commercial and residential purposes as a secondary bearing member. Further developments of thin walled members made it possible to use the CFS Sections as preliminary load carrying structural members. The reason is hot-rolled steel sections posses’ very low strength to weight ratio on CFS sections, and the production process of these sections is cost-effective and simple. This paper is about comparing the analysis results from CUFSM and ABAQUS of different channel sections. The loads will be applied at the edges of the members axially i.e., as a compression member with different boundary conditions.

A Comparative Analysis and Design of Industrial Building Using Hot Rolled Section and Cold Formed Section for Sustainability

Abstract: Structural Steel is a typical building material utilised in the building sector. Its main function is to serve as the framework for the structure i.e, the portion of the structure that keeps everything else in place. Steel is 100% recyclable, making it one of the greenest materials available. This study conducts a comparative analysis and design of an industrial building, evaluating the sustainability implications of employing hot-rolled and cold-formed steel sections. Examining mechanical properties, life cycle environmental impact, and cost-effectiveness, the research aims to provide insights into the structural and environmental benefits of each section type. By optimizing the integration of hot-rolled and cold-formed sections, the study seeks to enhance overall sustainability, considering factors such as energy consumption and material efficiency. Through case studies, this research offers a concise yet comprehensive exploration of how the combined use of these sections can contribute to environmentally conscious and resource-viable industrial building design. The findings aim to inform industry professionals, architects, and engineers about making sustainable choices in the construction process.

Experimental investigation on the cold-forming effect of high strength cold-formed steel sections

Many researches were carried out on the cold-forming effect of cold-formed steel sections while research on that of high strength cold-formed steel sections was quite few. Thus, an experimental investigation on the material property and residual stress of high strength cold-formed steel sections was carried out and the effect of residual stress on the overall stability bearing capacity was studied. It was found that: (1) the increase of yield strength of high strength cold-formed steel was similar to that of Q235 and Q345 cold-formed steel; (2) the residual stress at corner parts was much higher than that at flat parts and the bending residual stress of high strength cold-formed steel was much lower than that of Q235 and Q345 cold-formed steel; (3) residual stress would lead to a decline of the overall stability bearing capacity of axially loaded high strength cold-formed C-shaped steel sections and the effect became lower with the increase of strength grade.

Influence of elevated temperature on buckling capacity of mild steel-based cold-formed steel column sections– experimental investigation and finite element modelling

PurposeThe capability of steel columns to support their design loads is highly affected by the time of exposure and temperature magnitude, which causes deterioration of mechanical properties of steel under fire conditions. It is known that structural steel loses strength and stiffness as temperature increases, particularly above 400 °C. The duration of time in which steel is exposed to high temperatures also has an impact on how much strength it loses. The time-dependent response of steel is critical when estimating load carrying capacity of steel columns exposed to fire. Thus, investigating the structural response of cold-formed steel (CFS) columns is gaining more interest due to the nature of such structural elements.Design/methodology/approachIn this study, experiments were conducted on two CFS configurations: back-to-back (B-B) channel and toe-to-toe (T-T) channel sections. All CFS column specimens were exposed to different temperatures following the standard fire curve and cooled by air or water. A total of 14 tests were conducted to evaluate the capacity of the CFS sections. The axial resistance and yield deformation were noted for both section types at elevated temperatures. The CFS column sections were modelled to simulate the section's behaviour under various temperature exposures using the general-purpose finite element (FE) program ABAQUS. The results from FE modelling agreed well with the experimental results. Ultimate load of experiment and finite element model (FEM) are compared with each other. The difference in percentage and ratio between both are presented.FindingsThe results showed that B-B configuration showed better performance for all the investigated parameters than T-T sections. A noticeable loss in the ultimate strength of 34.5 and 65.6% was observed at 90 min (986℃) for B-B specimens cooled using air and water, respectively. However, the reduction was 29.9 and 46% in the T-T configuration, respectively.Originality/valueThis research paper focusses on assessing the buckling strength of heated CFS sections to analyse the mode of failure of CFS sections with B-B and T-T design configurations under the effect of elevated temperature.

Investigation of Parameters Affecting Rotational Behavior of Cold-Formed Steel Connection

This study aims to understand the behavior of connection, which holds an important key to efficient designs of the cold-formed steel structure. The focus is on examining parameters that affect the rotational stiffness and behavior of the cold-formed steel connection made of single-lipped channel sections with a bolt and gusset plate system. The numerical study has been conducted using component-based finite element analysis, with the studied parameters including bolt diameters, number of bolts in the group, size of the bolt group, thickness of the cold-formed steel cross-section, and thickness of the connecting plate. The effect of the variables is evaluated and explained by comparison. The result of the study reveals that the rotational behavior of the connection depends on the details of the assembly. For the given base connection, the parameters that give the greatest effect on the rotation stiffness and the moment capacity are the number of bolts and the bolt diameters, whereas the parameter that provides the least effect is the bolt spacing. On the other hand, the bolt group size is the most influential parameter for the member connection. For both types of connections, the thickness of the cold-formed steel section and the thickness of the gusset plate have shown limited effect on stiffness and strength. Using different variables in assembling the connection can also lead to different failure types, either bolt failure or excessive bolt hole deformation, which leads to plate failure. Doi: 10.28991/CEJ-2023-09-11-08 Full Text: PDF

Analytical study of lipped cold-formed steel sections with edge-stiffened hole subjected to axial compression load

Analytical study of lipped cold-formed steel sections with edge-stiffened hole subjected to axial compression load

Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

High-performance steel has emerged as an advanced structural material in the construction practice of industrial buildings, due to its excellent properties. However, fire poses a significant threat to cold-formed steel structures, as they are prone to deform and buckle under the exposure, potentially leading to building collapse. This study aimed to evaluate the post-fire web-crippling behaviour of high performance CFS sections for End Two Flange (ETF) and Interior Two Flange (ITF) load cases. Two types of specimens were used: CFS webs without holes and CFS webs with circular holes. All test specimens were heated according to the ISO 834 standard fire curve and were subsequently cooled by air or water. A total of 52 specimens (ambient and post-fire) were tested under ETF and ITF load conditions. The load-deflection behaviour and failure modes were evaluated through experimental and numerical analysis. Finite element modelling was used to compare the load-deflection behaviour and failure modes of CFS members with experimental results. The experimental results indicate that the web load-carrying capacity of the high-performance steel member decreases drastically as the heating duration increases. Furthermore, the ITF load case specimens exhibited a lower strength loss than the ETF load case specimens at elevated temperatures. There was an excellent agreement between the experimental and FEM results in terms of the load-carrying capacity and failure modes of high performance CFS.

State-of-the-Art: Integrating Fastener Technology and Design Guidelines for Enhanced Performance of Cold-Formed Steel Sections

Cold-formed steel (CFS) elements have gained significant attention in the field of structural engineering due to their numerous advantages, including high strength-to-weight ratio, cost-effectiveness, and ease of assembly and prefabrication. This review paper presents a comprehensive state-of-the-art analysis of the design and analysis of CFS structures, with a specific focus on columns and beams. The primary objectives and aims of this review paper are to provide a detailed assessment of the factors influencing the behavior and performance of CFS elements, including partial composite action, fastener spacing, bolt arrangement, web aperture, stiffeners, and connection spacing, to propose and present various formulas and methodologies that accurately estimate critical buckling loads, strength, and moment resistance for CFS members, and to emphasize the significance of proper screw and bolt placement in preventing premature failure and enhancing the overall load-carrying capacity of CFS structures. Additionally, the impact of temperature on the mechanical properties and performance of CFS members is discussed. The review paper proposes different formulas and methodologies to accurately estimate critical buckling loads, strength, and moment resistance for CFS members. Moreover, the paper highlights the importance of proper screw and bolt placement to prevent early failure and improve the overall load-carrying capacity of CFS structures. The discussion also emphasizes the need for revisions in existing standards and codes to provide more practical guidelines for designers and engineers. Overall, this state-of-the-art review paper provides valuable insights and recommendations for researchers and practitioners involved in the design and analysis of CFS elements.

Experimental study of innovative bolted shear connectors in demountable cold-formed steel–concrete composite beams

Although cold-formed steel (CFS) members have been widely used in structures, their application is limited due to the buckling and instability of these members. To enhance their strength and stiffness, they are often combined with other materials like concrete or timber. One of the main challenges in composite structures is ensuring proper connection between different components to facilitate safe shear load transfer. This is achieved through various types of shear connectors. Bolted shear connections are preferred over headed shear studs because they offer greater strength and can be easily dismantled. Headed shear studs welded onto a steel section are unsuitable for CFS members due to their low thickness.In this paper, we propose a novel demountable composite connection specifically designed for prefabricated CFS structures. The behavior of this connection was evaluated through fifteen push-out test specimens, with key variables including CFS section thickness and bolt diameter/strength. The ultimate load, stiffness, ductility, and failure modes of all specimens were determined. The results revealed that specimens with a higher thickness of CFS members experienced bolt fracture, exhibiting superior effective stiffness, strength, and ductility. Conversely, specimens with a lower thickness of CFS members failed due to distortional buckling of the CFS members. The test results underscore the importance of carefully designing and providing a proportionate CFS section thickness to ensure shear connectors fracture before the CFS members. This significantly improves the shear strength capacity of the composite connection with CFS sections and precast concrete slabs. Furthermore, the deconstructability of the connection at the end of its service life was investigated. The steel–concrete composite connection with precast concrete slabs and demountable bolted shear connections was also modeled using a 3D finite element method. The numerical model’s accuracy in simulating the observed structural behavior was confirmed against experimental data. Finally, appropriate and straightforward formulations for predicting the ultimate load of the CFS-concrete composite connection were proposed. It was concluded that the predictions of ultimate shear load capacity values by EC4, AISC, and AISI provisions for this composite connection are significantly less accurate.

Reliability of Cold-Formed Steel Sections Subjected to Web Crippling

This study aims to evaluate the structural safety of cold-formed steel sections subjected to concentrated loads in regions without transverse stiffeners, susceptible to web crippling, and dimensioned according to the North American Specification (AISI S100) and the Norma Brasileira (NBR 14762 2010) standard. Experimental data from various sections reported in the literature were analysed, obtaining professional factor statistics. Target reliability indices commonly used in the calibration of cold-formed steel standards were considered. A reliability analysis according to the First-Order Reliability Method (FORM) was developed for several action combinations found in the AISI and NBR standards. In addition to the scenarios prescribed by the AISI (2016), a scenario for the NBR 14762 (2010) standard is proposed, which, although it does not yet exist in the standard, was adopted for research purposes. In the proposed scenario, it was discovered that the resistance factor stipulated by the NBR 14762 (2010) standard did not produce satisfactory outcomes regarding a target reliability index of 2.5 in 10 out of 25 examined cases.

Structural performance of friction-grip bolted shear connectors in cold-formed steel composite beams

Nowadays, composite beams consisting of steel beams and concrete slabs are widely used in the construction industry. In this research, an experimental study was carried out to investigate the performance of friction-grip bolted shear connectors in composite beams with cold-formed steel sections. For this purpose, 17 full-scale push-out tests were examined according to EC4 in order to investigate the performance of this connection. Of particular interests were load-slip curves, the maximum shear capacity, ultimate slip (ductility) and failure modes. Experimental results show that the behavior of this connection is different from that of headed-stud shear connector. The diameter and strength of bolt and thickness of cold-formed steel section have the most critical effects on the shear capacity and ductility of these connections. Furthermore, 3D finite element modeling was performed and validated against experimental results. The results reveals that numerical models can estimate the capacity of friction-grip bolted shear connectors with acceptable accuracy. The results also highlight that the predominant failure mode in all specimens is bearing. Thus, the use of AISI equations to determine the bearing capacity of the screw holes as the shear capacity of friction-grip bolted shear connectors is recommended. It is also concluded that this connection possesses the necessary ductility according to the EC4 (= 6 mm) and is suitable for use in composite beams with cold-formed steel sections.

Web crippling behaviour of cold‐formed high‐strength steel unlipped channel beams

AbstractConstruction industries have increasingly sought to adopt Cold‐Formed Steel (CFS) sections as primary and secondary load‐carrying members. Also, the evolution of the CFS industry leads to fabrication of high strength CFS sections due to their added benefits such as higher strength‐weight ratio, most appropriate to employ in high‐rise and long‐span applications, and lesser carbon footprint. However, large width‐to‐thickness ratios of these thin‐walled beams make them vulnerable to local buckling failure, a major failure mode being web crippling when subjected to concentrated loads. The design standards predict the web crippling capacity of CFS sections according to the experimental studies conducted in previous years. Innovative concepts like the production of CFS using high‐strength materials should be examined undergoing web crippling. Therefore, the web crippling behaviour of the unlipped channel sections with material strength up to 1000 MPa under all four loading conditions: End‐Two‐Flange (ETF), Interior‐Two‐Flange (ITF), Interior‐One‐Flange (IOF) and End‐One‐Flange (EOF) was investigated in this study. Numerical simulations using Finite Element Analysis (FEA) software (ABAQUS) were conducted on 972 parametric studies following proper validation. New modified equations were proposed to predict the ultimate web crippling capacity of high strength unlipped channel sections and parametric analyses were carried out among various loading conditions.

A Regression-Based Approach for Assessing the Buckling Coefficient of Stiffened and Unstiffened Elements

Sustainable construction begins essentially by enabling the application of renewable and recyclable building materials. Cold-formed steel sections providing long-term sustainability and having a high strength-to-weight ratio are finding extensive application in the fields of construction and engineering. The Effective Width Method (EWM) and the Direct Strength Method (DSM) are the primary available analytical methods for the design of these sections. The design procedure for the buckling strength prediction of these analytical methods is inherently dependent on the critical buckling load, which in turn is influenced by the plate buckling coefficients. The plate buckling coefficient of either a stiffened or an unstiffened element is defined for varied boundary conditions and elemental stress ratios. Evaluating the design procedure for the critical buckling load, which is taken as the minimum of the elemental strengths, it was clearly evident that the analytical method yields highly conservative solutions. This conservative prediction is inherently caused by the application of individual plate buckling coefficients that fail to account for the inter-element interaction.The present research strives to propose a regression-based method for the determination of the critical buckling load. The symbolic regression analysis with the aid of machine learning is opted for to obtain more precise and reliable mathematical solutions for the buckling coefficients. The inter-element interaction and varied loading conditions are assessed for their influence and are accounted for in the expressions of the buckling coefficient. More reliable and accurate buckling strength prediction results with a broader conceptual approach are postulated.

Web crippling behaviour and design of aluminium SupaCee sections

AbstractSupaCee sections are addressed as one of the innovative section profiles which was introduced to the Cold‐Formed Steel (CFS) industry in the past decade. Longitudinal stiffeners and return lips are the unique features which ensured the better structural performance in terms of bending and shear for CFS sections. However, web crippling performance of CFS SupaCee section was the critical aspect to employ them in the industry as the concentrated loads could induce web crippling failures. Hence, there is a necessity to address web crippling performance of any innovative profiles to utilize them in appropriate locations. On that note, aluminum sections are now emerging in the industry as load bearing profiles considering their lightweight nature, corrosion resistance, ease of fabrication and high specific strength. Aluminium sections are considered as a replacement for CFS sections for modular constructions where the necessity of light weight is higher considering the transport costs and fabrication costs. However, web crippling performance of aluminum sections has to be analyzed to ensure the utilization in modular constructions. Hence, a superior section among available sections in terms of structural performances, aluminium SupaCee section, was considered for this study. Accordingly, a comprehensive numerical study was conducted considering various parameters such as section depth, thickness, bearing length and yield strength, after the successful validation process of the numerical models with the experimental scenarios of End‐Two‐Flange (ETF) loading condition. Ultimately, the results were compared with key parameters and suggestions and recommendations were stated for the utilization aluminum SupaCee sections in the industry.

Structural response of hybrid timber ‐ cold formed steel floors

AbstractThe paper examines the composite performance of hybrid steel‐timber lightweight floor assemblies incorporating cold‐formed steel (CFS) profiles and plywood (PW) flooring panels with varying degrees of shear connection achieved by means of self‐drilling screws. Material, push‐out, and three‐point short‐span floor tests with or without web openings were carried out. The results and observations from the tests provide a detailed insight into the inelastic properties and ultimate response of such floor systems. Push‐out tests indicate that denser connector arrangements increase connection stiffness, while push‐out and short beam tests suggest an optimum connector spacing equal to the beam depth for a balance between structural performance and constructability. The experimental observations indicate that the ultimate condition of the short composite beams was characterized by CFS web crippling under the load application point, followed by a pull‐through of the self‐drilling screws. Web openings reduced the strength of the floor elements compared to the members with full webs. Complementary numerical studies are undertaken using nonlinear finite element procedures which were validated against the beam tests, offering a detailed insight into the stress levels in the timber, steel, and connectors. Codified procedures for determining the capacity of composite CFS sections are compared with the test results, and guidance for the practical design and construction of such systems is given.

Web crippling behaviour of cold-formed steel channel sections having elongated edge-stiffened web holes under interior-two-flange loading condition

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 (Rp) and the equations based on the direct strength method (DSM) for CFS sections with elongated web holes were proposed.

Web crippling resistances of cold-formed stainless steel sections: A proposal for EN 1993-1-4

The current EN 1993-1-4 does not have supplementary web crippling design provision for cold-formed stainless steel sections under local transverse forces. Therefore, designers are generally referring to the guidance in EN 1993-1-3 for cold-formed carbon steel sections. Over the past decades, quite a substantial number of tests have been carried out worldwide to study the behaviour of cold-formed stainless steel sections undergoing web crippling, among which the majority of the data were focused on C-sections as well as square and rectangular hollow sections (SHS and RHS). To this end, tailor-made design provisions for these stainless steel sections can be developed. In this study, up-to-date web crippling test data on cold-formed stainless steel C-sections and SHS/RHS were firstly collected. The applicability of the web crippling design provisions as per the new version of EN 1993-1-3 to stainless steel sections was assessed. New design provisions for cold-formed stainless steel unstiffened C-sections (unlipped channels), stiffened C-sections (lipped channels) as well as SHS and RHS under local transverse forces are proposed in this study. The newly developed web crippling design provisions for C-sections and SHS/RHS were derived based upon reliability requirements as regulated in EN 1990 using available experimental data reported on austenitic, ferritic and duplex stainless steel types of various grades. The proposed design provisions for stainless steel sections have been made in line with the development of the new version of EN 1993-1-3 provisions and therefore are recommended to EN 1993-1-4 for calculating web crippling resistances under local transverse forces.

Structural performance of cold metal transfer welding technique on cold-formed steel flare v-groove welds

The performance and feasibility of a recent welding technique called Cold Metal transfer (CMT) welding technique for Cold-Formed Steel (CFS) welded sections is presented in this paper. The study focuses on understanding the behaviour of flare v-groove welds on back-to-back connected CFS sections subjected to longitudinal shear. A total of thirty lap shear specimens were fabricated and the parameters such as length of the weld and thickness of the weld were varied and tested under longitudinal loading. The weld geometry was observed under an optical microscope after polishing and chemical etching of the weld cross-section to determine the thickness of the weld for CMT flare v-groove welds. Based on the weld cross-section profiles, a set of calibrated welding parameters for 1.5mm CFS section is presented in the paper. The lap shear specimens failed in either transverse plate tearing of the individual cross-section or fracture of the weld at the weld contours. The test results show that AISI design standard yield over-conservative strength prediction and inaccurate failure modes for longitudinal flare v-groove welds. Therefore, a limiting ratio constituting of length of the weld, outstanding flange length, ultimate strength of parent material, and ultimate strength of wire electrode is proposed in the paper to accurately predict the failure mode. Additionally, a modified and reliable design equation is recommended to determine ultimate shear strength of CMT flare v-groove welds subjected to longitudinal loading.

Flexural Behavior of Built-Up Cold-formed Steel Channel Section Strengthened with Oriented Strand Board

The objective of the study is to determine the flexural behavior of the built-up cold-formed steel (CFS) channel section strengthened with an oriented strand board (OSB) in the three-point bending experiment. CFS with a variety of shapes and grades is classified as a steel-based material and exposed to buckling failure when subjected to compression or flexural load. Thus, the CFS channel section with 100 mm of the web, 50 mm of the flange, 12 mm of the lip, and 1.55 mm of thickness has been selected. Then, the built-up CFS channel section is designed by filling with an OSB between the gap of each section. Channel, face-to-face built-up, and back-to-back built-up CFS sections are three types of tested specimens. From the result and discussion, the specimen with back-to-back built-up CFS section is recognized to sustain the ultimate load with the highest value when compared with other specimens.

Non-linear 3D finite element analysis of built-up cold-formed steel section beam subjected to four-point bending load

The behaviour of cold-formed steel (CFS) built-up section beams under the flexural load has become an attentive area for search, especially with associated complex failure modes, such as local, distortional, lateral-torsional, and global buckling. Previous studies in this area have primarily focused on the compression capacity of CFS members, neglecting their flexural behaviour. Moreover, the CFS beam flexural analysis is more complex in terms of failure mode form and design. This study conducted A 3D non-linear finite element analysis (FEA) run on ABAQUS software on a CFS built-up section beam that was tested under four-point bending. This study examines the bending response of the built-up beam in terms of its load-bearing capacity, the ways in which it fails, and the stress distribution among its cold-formed steel components. The constitutive material laws for CFS, the screws modelling strategy and the contact interaction between the CFS components were considered in this study. The finite element model was verified by comparing it to the experimental results from a previously published study, focusing on the load–deflection response and how the beam failed. The results demonstrated that the FEA could replicate the flexural response of the CFS built-up section beam with an acceptable level of accuracy. Furthermore, the stress profile evaluation showed that the compression flange was the most affected component during the four-point bending loading. Overall, the FEA model developed in this study is a valid tool for predicting the bending behaviour of a CFS built-up section beam and assessing design variables for this type of beam under flexural loading.