Compressive Strength of Axially Loaded Built-up Sigma Cold Formed Sections Columns (original) (raw)
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Comparative Study and Analysis of Cold Formed Steel Columns Subjected to Axial Loading
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infrastructures, 2024
Cold-formed steel channel (CFSC) sections have gained widespread adoption in building construction due to their advantageous properties, including superior energy efficiency, expedited construction timelines, environmental sustainability, material efficiency, and ease of transportation. This study presents a numerical investigation into the axial compressive behavior of CFSC section columns. A rigorously developed finite element model for CFSC sections was validated against existing experimental data from the literature. Upon validation, the model was employed for an extensive parametric analysis encompassing a dataset of 208 CFSC members. Furthermore, the efficacy of the design methodologies outlined in the AISI Specification and AS/NZS Standard were evaluated by comparing the axial load capacities obtained from the numerically generated data with the results of four previously conducted experimental tests. The findings reveal that the codified design equations, based on nominal compressive resistances determined using the current direct strength method, exhibit a conservative bias. On average, these equations underestimate the actual load capacities of CFSC section columns by approximately 11.5%. Additionally, this investigation explores the influence of eccentricity, cross-sectional dimensions, and the point-of-load application on the axial load capacity of CFSC columns. The results demonstrate that a decrease in section thickness, an increase in column length, and a higher degree of eccentricity significantly reduce the axial capacity of CFSC columns.
Strength and Ductility of Steel Cold-Formed Section Beam to Column Bolted Connections
2017
Recently, there has been a rapid growth in the construction of low to medium rise houses and portal frames with moderate spans using steel cold-formed sections (CFS) as primary structural elements. However, the strength and stability of steel frames depend largely on the nature of the connections between their elements. This paper presents a study of the structural performance of three configurations of beam to column bolted connections of single-lipped channel CFS. In the first model, a sleeve element is used to connect the beam to the column. The sleeve element has a channel cross section with a tapered web. This enables the transmission of forces through the flanges as well as the webs. In the second model, the beam is connected to the column by a tapered gusset plate. Bolts connect the webs of the beam and column sections to the gusset plate. The third model depends on placing a knee-bracing element between the beam and the column; consequently, forces are transmitted mainly fro...
Journal of Constructional Steel Research, 2019
There are numerous parameters that influence the behavior of built-up steel columns. This paper reports an experimental investigation carried out on cold-formed steel (CFS) built-up columns composed of four unstiffened CFS equal angle sections connected by lacings intermittently along their heights. The man parameters varied in the test specimens were the width of end plate, the lacing slenderness ratio, the chord flat width-to-thickness ratio and the lacing configurations. Six pin-ended test specimens were tested under monotonically increasing concentric axial loading. The test result output viz. ultimate column strengths, load vs. displacement response, mode of failure, and deformed shapes were used to investigate the effect of above-mentioned parameters on the axial behavior of CFS built-up laced columns. The current standards for CFS structures were used to predict the column strengths for the sake of comparison. Furthermore, a numerical validation of the test results was carried out using a finite element software ABAQUS. Test results indicate that the lacing slenderness, the lacing configuration, and the end plate width affect the column behavior in CFS laced built-up columns significantly.
Analytical and Experimental Study on Cold-Formed Steel Built-Up Sections for Bending
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In the construction of steel structures, the two most common types of structural members are hot-formed and cold-formed members. This paper mainly describes the analytical and experimental research on the strength and characteristics of CFS bolted built-up sigma sections having different structural arrangements under bending. The cross-sectional dimensions for the parametric study were selected by the sizes available in the market. In this paper, ANSYS workbench software was used to perform FE modeling and observe the local, flexural, and interaction of these buckling. Then, experimental study was performed by varying the arrangement of open section beams between face-to-face and back-to-back, connected using bolts or fasteners different spacings. Further, we conducted bending tests on cold-formed steel built-up members having simple edge stiffeners in the middle. Comparing both analytical and experimental studies, the results indicate that the back-to-back connected built-up beam s...
Buckling strength of axially loaded cold formed built-up I-sections with and without stiffened web
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This paper presents a numerical procedure using finite element analysis for the calculation of axial strength of cold formed steel built-up I-sections composed of two back-to-back channels. The material nonlinearity of the flat and corner portions of the section were incorporated in the model. The effects of initial local and overall geometric imperfections as well as the membrane residual stresses have been taken into consideration in the finite element model. The results of the nonlinear finite element analysis were compared with the available experimental results, and with the calculated theoretical buckling capacities based on the AISI design provisions. A parametric study was carried out using the developed finite element model to study the effects of member and cross-section geometries and imperfection values on the strength of cold-formed steel built-up Icolumns. The column strengths predicted from the parametric study were compared with the design strengths calculated using the American Specification. The results of the parametric study showed that the design provisions specified in the American Specifications are generally conservative for long and medium length columns, but may give un-conservative estimates for some of the short columns.
Ultimate Load of Built-Up Cold Formed Steel Column
ARPN journal of engineering and applied sciences, 2014
Cold formed steel (CFS) has been used as the primary structure for flexural and compression member due to varieties of advantages such as high strength to weight ratio, high corrosion resistance, and ease of fabrication. The criteria need to be considered in improving the structural strength is the fabrication method. Fast and easy fabrication can produce an efficient structure. Built-up of normal CFS into new member with higher strength can be produced efficiently by attaching the normal steel using self-drilling screw. CFS channel with constant size has been used to produce built-up, back to back (BTB), and box-up (BU) with varieties of length. The constant spacing were used at 400 mm centre to centre along its length and supported by using an angle plate that screw through its web. 18 nos of columns were tested for compression until the column cannot resist any increment of load. The ultimate loads were compared to the predicted buckling load using EC3-1-3. The prediction of colu...
Structural Performance of Cold Formed Section Beam to Column bolted Connections
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The semi-rigid nature of the cold formed section beam to column connections is primarily due to the distortion, tearing of column section plates, and distortion of beams end sections. Stability of such structures usually depends signif icantly on the behavior of these connections. In this study, Nonlinear finite element model were done for two cold formed section assemblies to evaluate their rotational stiffness and capacity. In the first assembly, both the beam and column having a back to back lipped sigma cold formed sections. However, in the second assembly, lipped back to back channel section connected to box column section. The beams and columns are connected together using gusset plate or gusset plate inaddition to angles between the beam and column flanges. In the model, the column ends were fixed, and the beam cantilever end allowed to move vertically. The out of plane deformation were prevented by means of lateral restraints attached to the specimens at the tip of the horiz...