Investigation on structural behaviour of composite cold-formed steel and reinforced concrete flooring systems

Omar A. Shamayleh,Harry Far 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.6

Composite flooring systems consisting of cold-formed steel joists and reinforced concrete slabs offer an efficient, lightweight solution. However, utilisation of composite action to achieve enhanced strength and economical design has been limited. In this study, finite element modelling was utilised to create a three-dimensional model which was then validated against experimental results for a composite flooring system consisting of cold-formed steel joists, reinforced concrete slab and steel bolt shear connectors. This validated numerical model was then utilised to perform parametric studies on the performance of the structural system. The results from the parametric study demonstrate that increased thickness of the concrete slab and increased thickness of the cold formed steel beam resulted in higher moment capacity and stiffness of the composite flooring system. In addition, reducing the spacing of bolts and spacing of the cold formed steel beams both resulted in enhanced load capacity of the composite system. Increasing the concrete grade was also found to increase the moment capacity of the composite flooring system. Overall, the results show that an efficient, lightweight composite flooring system can be achieved and optimised by selecting suitable concrete slab thickness, cold formed beam thickness, bolt spacing, cold formed beam spacing and concrete grade.

Research on cold-formed steel connections: A state-of-the-art review

Ying Qin,Zhi-Hua Chen 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.1

Cold-formed steel structures are increasingly attractive due to their benefits of good mechanical performance and constructional advantages. However, this type of construction is still not fully exploited as a result of the acknowledged difficulties involved in forming construction-efficient and cost-effective connections. Furthermore, there is a lack of information on the structural behavior of the cold-formed steel connections. In this study, the research on various cold-formed steel connections was comprehensively reviewed from both fundamental and structural points of view, based on the available experimental and analytical data. It reveals that the current design codes and guidelines for cold-formed steel connections tend to focus more on the individual bearing capacity of the fasteners rather than the overall structural behavior of the connections. Significant future work remains to be conducted on the structural performance of cold-formed steel connection. In addition, extensive previous research has been carried out to propose and evaluate an economical and efficient connection system that is obtained from the conventional connecting techniques used in the hot-rolled industry. These connecting techniques may not be suitable, however, as they have been adopted from hot-rolled steel portal frames due to the thinness of the sheet in cold-formed steels. The review demonstrates that with the increasing demand for cold-formed steel constructions throughout the world, it is crucial to develop an efficient connection system that can be prefabricated and easily assembled on site.

Cold-Forming Effect on Stainless Steel Sections

Milon K. Howlader,Jan Marik,Michal Jandera 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.2

Stainless steel exhibits greater extent of strain hardening than carbon steel, which leads to significant change in mechanical properties (increase in yield strength and decrease in ductility) of the stainless steel material due to the cold forming process. These changes of the mechanical properties depend mainly on the magnitude of residual stresses and equivalent plastic strain induced by the cold working. This paper presents an analytical model for determining the residual stresses and the corresponding plastic strain by means of Maple software simulating the cold forming process. The analytical model in Maple is validated by the previous numerical and experimental data of cold formed sheets. The increased material properties are determined after cold forming for corners and flat faces of sections considering the residual stresses and plastic strain and validated with the previous test results. For the prediction of the increased yield strength, new material properties with respect to the induced plastic strain based on tests are set for cold bending process in the analytical model. The analysis for the increased yield strength is calculated for four stainless steel grades, i.e., austenitic (1.4404), ferritic (1.4003), lean-duplex (1.4162) and duplex (1.4462) and the results are compared with the previous predictive models of the strength increase.

Flexural-torsional buckling tests of cold-formed steel compression members at elevated temperatures

Yasintha Bandula Heva,Mahen Mahendran 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.3

Current design standards do not provide adequate guidelines for the fire design of cold-formed steel compression members subject to flexural-torsional buckling. Eurocode 3 Part 1.2 (2005) recommends the same fire design guidelines for both hot-rolled and cold-formed steel compression members subject to flexural-torsional buckling although considerable behavioural differences exist between cold-formed and hot-rolled steel members. Past research has recommended the use of ambient temperature cold-formed steel design rules for the fire design of cold-formed steel compression members provided appropriately reduced mechanical properties are used at elevated temperatures. To assess the accuracy of flexural-torsional buckling design rules in both ambient temperature cold-formed steel design and fire design standards, an experimental study of slender cold-formed steel compression members was undertaken at both ambient and elevated temperatures. This paper presents the details of this experimental study, its results, and their comparison with the predictions from the current design rules. It was found that the current ambient temperature design rules are conservative while the fire design rules are overly conservative. Suitable recommendations have been made in relation to the currently available design rules for flexural-torsional buckling including methods of improvement. Most importantly, this paper has addressed the lack of experimental results for slender cold-formed steel columns at elevated temperatures.

Study on the Buckling Behaviour of Cold-Formed Angles in Transmission Towers

Fengli Yang,Junke Han,Jingbo Yang,Zhenbao Li 한국강구조학회 2011 International Journal of Steel Structures Vol.11 No.4

Considering the structural characteristics of transmission towers, four sections of cold-formed angles with different slenderness ratios and constrained types were selected for the experimental and numerical study. Experiments and finite element analysis for the ultimate loads of the compression cold-formed angles were carried out. The finite element model well predicts the buckling behaviour of the cold-formed members. For the axial compression members, the load-strain curves as well as the ultimate loads were analyzed, and the experimental ultimate loads were compared with those of calculated by the applicable standards. It shows that the applicable standards aren’t adaptive to the strength design of the compression cold-formed members in transmission towers. Through the analysis of the experimental and FEA results, the fitting curve of the stability coefficients for the cold-formed members in transmission towers was determined. The ultimate loads calculated by the fitting curve are well agreed with the experimental values, especially for the members with relatively low slenderness ratios. Some modification suggestions were proposed for the calculation of the ultimate load for the axial compression cold-formed angle. Experimental analysis on the cold-formed members of the other five constrained types was completed, and the modification formulas of the slenderness ratios for members of different constrained types were obtained.

A Study on the Sheet Forming of the Lower Seat Rail using 1180 TRIP Steel

Oh, Won-Jung,Lee, Choon-Man Korean Society for Precision Engineering 2018 International Journal of Precision Engineering and Vol.19 No.2

The automotive industry is investing great effort to reduce the weight of vehicles to improve fuel efficiency and performance. To develop a lighter vehicle, Ultra high strength steel (UHSS) is being increasingly used, and is the focus of efforts to develop innovative sheet steel with high strength, durability and formability, including projects such as Ultra-light steel auto body (ULSAB) and Ultra-Light steel auto closure (ULSAC). Because UHSS is very difficult to form at room temperature, roll forming and hot forming processes have been proposed. However, the productivity of these processes is significantly lower than cold forming. In this study, a seven step cold forming process is proposed for forming a lower seat rail using 1180 TRIP steel, and was found to be more conducive to productivity than other processes. The design of the proposed forming process was determined by forming analysis and experiment. The forming analysis was carried out using DEFORM software, and the experiments were carried out using a mechanical press machine. The weight of conventionally formed seat rails (DP 980) and the proposed seat rails (1180 TRIP steel) were compared to determine the weight reduction.

Numerical investigation of web crippling strength in cold-formed stainless steel lipped channels with web openings subjected to interior-two-flange loading condition

Amir M. Yousefi,Asraf Uzzaman,James B.P. Lim,G. Charles Clifton,Ben Young 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.3

In cold-formed stainless steel lipped channel-sections, use of web openings for service purposes are becoming increasingly popular. Web openings, however, result in the sections becoming more susceptible to web crippling. This paper presents a finite element investigation into the web crippling strength of cold-formed stainless steel lipped channel-sections with circular web openings under the interior-two-flange (ITF) loading condition. The cases of web openings located centred and offset to the bearing plates are considered in this study. In order to take into account the influence of the circular web openings, a parametric study involving 2,220 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades. From the results of the parametric study, strength reduction factor equations are proposed. The strengths obtained from reduction factor equations are first compared to the strengths calculated from the equations recently proposed for cold-formed carbon steel lipped channel-sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 17%. New coefficients for web crippling strength reduction factor equations are then proposed that can be applied to all three stainless steel grades.

Numerical Analysis and Experimental Investigation on Behavior of Cold-Formed Steel Castellated Beam with Diamond Castellation

S. Prabhakaran,S. A. Maboob 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

The main purpose of the current research work is to achieve an economical cold formed steel castellated beam with diamond castellation with limited buckling. In this way, to study the behavior of cold formed steel castellated beam with diamond castellation by the provision of diff erent methods of placing the stiff eners for the sections is an main scope of the work. It can be achieved through this paper, which gives an Numerical, Analytical Study and Experimental investigation on the performance of cold-formed steel Castellated beams with Diamond Castellation shape. Perforations in web has been carried out to know its structural behaviour as simply supported beam under pure bending. The castellated steel beams with perforated web epitomize a new inventive which has occurred in the past span for the short- and medium length of beams. The Cold- Formed Steel provides a substantial weight reduction of these beams with castellation, compared to the hot-rolled beams. The Castellated Beam has made with 2 mm thickness CFS Steel, used all over the Beam. In the study, the Castellated Beam has been performed with three types of Stiff ener Designs at web of the Beam. Beam with intercept Stiff eners plates at web has used. Both stiff ened and unstiff ened Castellated beam (Beam with Parallel, Perpendicular and intercept Stiff eners) were tested for numerical and experimental Testings. Finally, numerical analysis using ABAQUS 6.11 results are evaluated and the experimental results were confi rmed with the results obtained from the fi nite element analysis. Based up on the numerical analysis and experimental investigation the diff erent failure and buckling modes of the proposed beams has been studied and the load carrying capacity of beams has been predicted.

Residual stress of cold-formed thick-walled steel rectangular hollow sections

Xingzhao Zhang,Su Liu,Mingshan Zhao,Sing-Ping Chiew 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.4

This paper presents the experimental and numerical study on the distribution of transverse and longitudinal residual stresses in cold-formed thick-walled structural steel rectangular hollow sections manufactured by indirect technique. Hole-drilling method is employed to measure the magnitude of the transverse and longitudinal surface residual stress distribution, and the effects of the residual stresses are evaluated qualitatively by sectioning method. It is shown that compared to normal cold-formed thin-walled structural hollow sections (SHS), the coldformed thick-walled SHS has similar level of residual stress in the flat area but higher residual stresses in the corner and welding areas. Both the transverse and longitudinal residual stresses tend to open the section. In order to predict the surface residual stresses in the corners of the cold-formed thick-walled SHS, an analytical model is developed. 2D finite element simulation of the cold bending process is conducted to validate the analytical approach. It is shown that in analyzing bending for thick-walled sections, shifting of neutral axis must be considered, since it would lead to nonlinear and non-symmetrical distribution of stresses through the thickness. This phenomenon leads to the fact that cold-formed thick-walled SHSs has different distribution and magnitude of the residual stresses from the cold-formed thin-walled SHSs.

Web crippling strength of cold-formed stainless steel lipped channel-sections with web openings subjected to interior-one-flange loading condition

James B.P. Lim,Amir M. Yousefi,Asraf Uzzaman,Ying Lian,G. Charles Clifton,Ben Young 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3

In cold-formed stainless steel lipped channel-sections, web openings are becoming increasingly popular. Such openings, however, result in the sections becoming more susceptible to web crippling, especially under concentrated loads applied near the web opening. This paper presents the results of a finite element parametric study into the effect of circular web openings on the web crippling strength of cold-formed stainless steel lipped channelsections for the interior-one-flange (IOF) loading condition. This involves a bearing load applied to the top flange of a length of member, away from the end supports. The cases of web openings located centred beneath the bearing load (i.e. beneath the bearing plate delivering the load) and offset to the bearing plate, are considered. Three grades of stainless steel are considered: duplex EN1.4462, austenitic EN1.4404 and ferretic EN1.4003. In total, 2218 finite element models were analyzed. From the results of the parametric study, strength reduction factors for load bearing capacity are determined, where these reduction factors are applied to the bearing capacity calculated for a web without openings, to take account the influence of the web openings. The strength reduction factors are first compared to equations recently proposed for cold-formed carbon steel lipped channel-sections. It is shown that for the case of the duplex grade, the strength reduction factor equations for cold-formed carbon steel are conservative but only by 2%. However, for the cases of the austentic and ferritic grades, the cold-formed carbon steel equations are around 9% conservative. New strength reduction factor equations are proposed for all three stainless steel grades.