Numerical investigation and design of cold-formed steel built-up open section columns with longitudinal stiffeners

Zhang, Jiahui; Young, Ben

doi:10.1016/j.tws.2014.12.011

Cited by 121 publications

(40 citation statements)

References 11 publications

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“…The stress-strain curve used in the finite element analysis (FEA) for the CFS profiles was based on tensile coupon test results and at the same time on other studies of literature [14,15,17,23], with a nominal yield strength of 320 MPa, a tensile strength of 390 MPa and a modulus of elasticity of 210 GPa. Residual stresses and cold-work of forming (where the apparent yield stress in the corners is increased) were ignored in these analyses, in other words, the mechanical properties of steel were assumed to be uniform across the crosssection, like other researchers in this field did [9,24]. The thermal properties of the CFS sections at elevated temperatures considered in the model (mass density, thermal conductivity and specific heat) were those given in EN1993-1-2:2004 [25] and the reduction factors for the modulus of elasticity and the yield strength of steel at elevated temperatures were obtained from the annex E of EN1993-1-2:2004 [25], whereas the expansion was taken from [26].…”

Section: Materials Modellingmentioning

confidence: 99%

“…This arises because the local buckling slenderness (width-tothickness ratio) of the sub-elements is smaller than that of the original plate element. The shape, size and position of intermediate stiffeners significantly affects the stability of cold-formed steel members [8,9]. The intermediate stiffeners must also have adequate rigidity to prevent out-ofplane deflections in the plate element in the region of the stiffener, thus allowing that under uniform compression this area of the section becomes fully stressed.…”

Section: Introductionmentioning

confidence: 99%

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10.26: Parametric numerical analysis of cold‐formed steel Σ‐shaped beams under fire

Laím

Rodrigues

2017

ce papers

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A numerical investigation into the structural behaviour of cold formed steel beams commonly used in warehouses and industrial buildings subjected to fire is presented in this paper. The structural performance of cold-formed steel beams under fire conditions has been studied over the last years. However, the great majority of them have been performed on single and lipped channel beams and assumed that the internal forces and moments at supports of the members remain unchanged throughout the fire exposure. Hence, a detailed parametric numerical investigation into the response of axially and rotationally restrained compound cold-formed steel beams in fire has been addressed in this paper. Therefore, in the first phase of this research, a suitable finite element model was developed and calibrated with results of experimental fire tests previously carried out by the authors. And then, a parametric analysis was undertaken using the calibrated finite element model with the purpouse of investigating numerically the effect of some parameters such as section geometry, initial applied load on the beam, slenderness and the influence of those two ki nds of elastic restraint on the critical temperature of the beams. Finally, the results of this research showed mainly that the critical temperature of this type of beams with elastically restrained thermal elongation may drop significantly and, beyond a certain value of axial or rotational stiffness of the surrounding structure it may be no longer possible to change the fire response of them.

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Section: Materials Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

10.26: Parametric numerical analysis of cold‐formed steel Σ‐shaped beams under fire

Laím

Rodrigues

2017

ce papers

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“…This finding indicates that in built-up members a degree of composite action between components sections is achieved due to presence of fasteners. Zhang and Young [5] presented a modified DSM and showed that predicted design strengths are reliable and conservative for built-up open section columns. Georgieva et al [6] investigated the applicability of the DSM for design of built-up CFS through experimental studies and suggested that a similar modified design methodology based on DSM can be adopted in structural standards.…”

Section: Introductionmentioning

confidence: 99%

07.13: On extending the direct strength method to the design of cold‐formed steel built‐up columns

2017

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This paper presents a numerical investigation of the effects of discrete fasteners on the buckling behaviour of cold-formed steel (CFS) built-up columns and concludes with the assessment of the applicability of the current direct strength method (DSM) to the design of these members. To this end, the compound strip method is first utilised to accurately model the buckling behaviour of CFS built-up columns under axial compression via introducing connecting elements to represent the contribution of discrete fasteners. A series of elastic buckling analyses with different levels of composite action are carried out to obtain the "signature curves" corresponding to the considered CFS built-up sections. The performed studies comprise of variations in cross-sections, end boundary conditions and fastener spacing. Utilising the developed numerical techniques, the ultimate strength of the sections are estimated and an adjustment procedure is suggested to extend the current DSM equations to the design of CFS built-up columns. The proposed adjustment is verified against the existing experimental data and shown to be capable and accurate in capturing the expected behaviour of CFS built-up members with or without stiffeners.

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“…In addition, Wang and Young [5] studied the effect of both cross-sectional dimensions and fastener spacing on the ultimate strength of built-up box and I beams with intermediate fasteners. Later, the effect of edge and web stiffeners on the behaviour of built-up I-columns were investigated in [6] via extensive parametric studies. The FSM has been widely used for elastic buckling analysis of CFS members, but its range of application is mostly limited to single sections and simple end boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

“…[7,8]. Some attempts have been made to extend the application range of conventional FSM to built-up sections via applying nodal multi-point constraints that tie any desired DOF from the adjacent plate components continuously along the length of the member [9] or through modelling fasteners as continuous longitudinal solid stiffeners [6]. However, these assumptions may not represent the actual effect of discrete fasteners and fail to accurately capture the level of composite action.…”

Section: Introductionmentioning

confidence: 99%

07.20: Application of the compound strip method in buckling analysis of cold‐formed steel built‐up sections

2017

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In this paper, the compound strip method is utilised and extended for the stability analysis of cold-formed steel built-up sections. The discrete fasteners are incorporated in the analysis such that they can be placed anywhere within the length of the member. A beam element with geometrical and material properties of the fastener is adopted to model the connection between the individual sections. The stiffness matrix terms for the connection element are derived and added directly to the global stiffness matrix of the considered built-up sections. The proposed numerical technique is verified through various examples and the results are compared with the finite element solutions. The results obtained demonstrate that the developed technique can accurately and efficiently model the behaviour of cold-formed steel built-up sections. Furthermore, the influence of the fasteners properties, their longitudinal spacing and also the boundary conditions on the overall buckling behaviour of built-up sections is examined through numerical examples. The simplicity of the proposed technique facilitates an extensive parametric study of cold-formed built-up sections including the search for optimal placement of fasteners and combinations of component sections in built-up profiles.

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Numerical investigation and design of cold-formed steel built-up open section columns with longitudinal stiffeners

Cited by 121 publications

References 11 publications

10.26: Parametric numerical analysis of cold‐formed steel Σ‐shaped beams under fire

10.26: Parametric numerical analysis of cold‐formed steel Σ‐shaped beams under fire

07.13: On extending the direct strength method to the design of cold‐formed steel built‐up columns

07.20: Application of the compound strip method in buckling analysis of cold‐formed steel built‐up sections

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