Face-to-face built-up cold-formed steel channel sections are becoming increasingly popular for column members in cold-formed steel structures; its applications include cold-formed steel trusses, space frames and portal frames. In such an arrangement, the independent buckling of the members is resisted by intermediate fasteners. In the literature, no research is available for such face-to-face built-up cold-formed steel columns. The issue is addressed herein. This paper presents the results of 36 experimental tests, conducted on face-to-face built-up cold-formed steel channel-sections covering a wide range of slenderness from stub to slender columns. A nonlinear finite element model is then described that shows good agreement with the experimental results. The finite element model includes material non-linearity, initial imperfections and modelling of intermediate fasteners. Both finite element and experimental results are compared against the design strengths calculated in accordance with the American Iron and Steel Institute (AISI), Australian and New Zealand Standards (AS/NZS) and Eurocode (EN 1993-1-3). The verified finite element model is used for the purposes of a parametric study comprising 90 models. The effect of fastener spacing on the axial strength was investigated. From the results of experiments and finite element investigations, it is shown that the design in accordance with the AISI & AS/NZS and Eurocode (EN 1993-1-3) is generally conservative by around 15%, however, AISI & AS/NZS and Eurocode (EN 1993-1-3) can be un-conservative by 8% on average for face-to-face built-up columns failed through local buckling.

Experimental and numerical investigation into the behaviour of face-to-face built-up cold-formed steel channel sections under compression

Experimental and numerical investigations on the axial capacity of cold-formed steel built-up box sections

https://digital.library.unt.edu/ark:/67531/metadc1065412/m2/1/high_res_d/Structures_upd.pdf

Seismic Response and Engineering of Cold-formed Steel Framed Buildings

Experiments on the global buckling and collapse of built-up cold-formed steel columns

This paper aims at investigating the structural response and predicting the ultimate strength of the cold-formed built-up I-section columns affected by local, distortional, global and in particular by the local-distortional (LD) interactive and local-distortional-global (LDG) interactive buckling modes. For this purpose, a total of 18 single C-section columns and 18 built-up I-section columns were tested under uniaxial compression load, respectively. The cross-sectional dimension, the thickness and the length of the tested members were varied in the test so as to cover a wide range of local, distortional and overall slenderness. It was shown in the test that noticeable LD interaction was observed for a built-up column with short length as well as LDG interaction for a built-up column with intermediate length. Due to the clear evidence obtained in the test that LD and LDG interactions cause substantial ultimate strength erosion in cold-formed built-up I-section column, a novel direct strength based method was proposed in this paper to quantify such an erosion effect. The validity of the proposed method was then verified by comparing the results obtained from the proposed method with the test results in this paper as well as several other test results in the literature. The comparison results proved that the proposed method can be used successfully in estimating the ultimate strength of cold-formed built-up I-section column affected by pure buckling mode as well as interactive buckling mode.

/pdf/experimental-investigation-and-a-novel-direct-strength-3g3doh0j6c.pdf

Experimental investigation and a novel direct strength method for cold-formed built-up I-section columns

The use of cold-formed thin-walled steel structures has increased in recent years, and some built-up section members are motivated and also widely used for their excellent structural behaviors. In this paper, a series of axially-compressed tests on built-up box section members composed of two C-section by self-drilling screws at flanges are conducted. The differences of global, local and distortional buckling behaviors between members with built-up and single sections are investigated at first. Then the effects of installation error and fastener spacing on ultimate load-carrying capacity of built-up members are analyzed. A strength estimation method for built-up members under axial compression is proposed based on the experimental investigation in this paper, as well as some existing experiments, and corresponding numerical analysis studies. Finally, the predicted capacity obtained by using the proposed strength estimation method is compared with experimental results and the nominal axial strength determined according to the AISI provisions, by which the suitability and accuracy of the proposed strength estimation method have been established.

Ultimate load-carrying capacity of cold-formed thin-walled columns with built-up box and I section under axial compression

The paper presents experimental and numerical investigation of cold-formed steel (CFS)–framed walls sheathed with corrugated steel sheets. The new wall technology is considered as an alternative shear wall configuration for midrise buildings at strong earthquake and high-wind regions because of its attributes of noncombustibility and higher structural performance than the conventional shear wall types. However, design provisions of such corrugated sheathed CFS-framed shear walls have not been included in the current design standards. To establish comprehensive database information and to observe the performance of the bearing wall for the first time, a test program of full-scale wall assemblies using corrugated steel sheathing was conducted. The test specimens included both shear wall specimens and bearing wall specimens under lateral and vertical/gravity loading. In accordance with the full-scale tests, a numerical model was developed in a computer program, and seismic performance assessment was ...

Experiments and Simulations of Cold-Formed Steel Wall Assemblies Using Corrugated Steel Sheathing Subjected to Shear and Gravity Loads

Built-up sections are widely used in cold-formed thin-walled steel frames. This paper mainly investigates the in-plane behaviour of built-up box beams with nested C section and U section under pure bending about strong and weak axis. The four-point bending test was conducted on a total of 7 groups of specimens, including built-up box sections (CU) and individual sections (C, U). A finite element model is developed and verified by the test results for further parametric analysis. The stress distribution at mid-span cross-section shows that the components in built-up beams can resist the bending moment together. For built-up box beams bending about strong axis, the reasonability of the capacity superposition method and equivalent method is assessed by the discussion on test results and numerical analysis results. The equivalent box section is suggested to calculate the flexural strength of built-up box beams bending about weak axis. Finally, the comparison between predicted and actual flexural strength indicates that this simplification of the proposed method can slightly under-estimate the flexural strength.

Investigation on flexural strength of cold-formed thin-walled steel beams with built-up box section

This research is focused on the behavior of a novel cold-formed steel (CFS) shear wall system- steel sheathed cold-formed steel trussed shear wall (SSCFSTSW), which is different in skeleton configuration compared to conventional steel sheathed CFS framed shear wall. A test program was conducted on shear walls of various configurations. The walls differed in sheathing, chord studs and skeleton configurations. The results indicated that SSCFSTSW gave a significantly higher ultimate strength than that obtained from conventional shear walls. Based on the results, detailed discussion of the influence of different configurations on the performance of shear walls is given.

Testing of steel sheathed cold-formed steel trussed shear walls

Cold-formed thin-walled steel residential building systems, because of their good environment protection, seismic performance, and high construction efficiency, have been widely used in the United States, Canada, Japan, and Australia, and recently, they also have had good application in China. Although a variety of studies have been carried out all over the world in the last 20 years, there is no related design code for this kind of building in China. For this reason, a series of research has been conducted in China recently, considering the consistency of standard systems in structural design in China and the newest development in the world. The contents of the paper can be divided into two parts. First, the major research works conducted by the authors over the last 5 years and the main findings are reviewed and summarized. Second, based on a Chinese professional standard, a brief summary of the design methods for cold-formed thin-walled steel framing residential buildings developed by the autho...

Yuanqi Li

Papers

Ultimate load-carrying capacity of cold-formed thin-walled columns with built-up box and I section under axial compression

Experiments and Simulations of Cold-Formed Steel Wall Assemblies Using Corrugated Steel Sheathing Subjected to Shear and Gravity Loads

Investigation on flexural strength of cold-formed thin-walled steel beams with built-up box section

Testing of steel sheathed cold-formed steel trussed shear walls

Experimental Investigation and Design Method Research on Low-Rise Cold-Formed Thin-Walled Steel Framing Buildings