Mode interaction in thin-walled equal-leg angle columns

Mesacasa, Enio; Dinis, Pedro Borges; Camotim, Dinar; Malite, Maximiliano

doi:10.1016/j.tws.2013.06.021

Cited by 37 publications

(21 citation statements)

References 10 publications

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“…10 and Fm=1.00 are the mean values of the material and fabrication factors, respectively, (iii) β0 is the target reliability index (β0=2.5 for structural members in LRFD), (iv) VM=0.10, VF=0.05 and VQ=0.21 are the coefficients of variation of the material factor, fabrication factor and load effect, respectively, (v) CP is a correction factor depending on the numbers of tests (n) and degrees of freedom (m=n-1), and (vi) Pm and VP are the mean and standard deviation of the "exact"-to-predicted ultimate strength ratios Pu /Pnfte. Indeed, it was found that the Fm initial imperfection amplitude and (mostly) sign have a strong impact on the angle column failure load [9,16]. Note that a similar behavioural feature was observed in the context of cold-formed steel PC column tests [11].…”

Section: Merit Assessment Of the Dsm-based Design Approach For Hot-romentioning

confidence: 76%

“…The structural behaviour and design of thin-walled equal-leg angle columns has attracted the attention of several researchers in the past, namely Kitipornchai & Chan [1], Adluri & Madugula [2], Popovic et al [3], Young [4], Rasmussen [5] and, more recently, Dinis et al [6], Shi et al [7], Silvestre et al [8] and Mesacasa Jr. et al [9]. As far as the design is concerned, a fair amount of work has been devoted to develop rules and procedures to predict the ultimate strength of short-to-intermediate cold-formed steel columns with rather slender legs (width-to-thickness ratios b/t above 20), adopting mostly local buckling concepts.…”

Section: Introductionmentioning

confidence: 99%

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13.11: DSM design approach for hot‐rolled steel angle columns

2017

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This work reports the latest results of an ongoing investigation on the Direct Strength Method (DSM) design of hot-rolled steel equal-leg angle columns with fixed and pinned (cylindrical or spherical hinges) supports and short-to-intermediate lengths, i.e., buckling in flexural-torsional modes. It extends the scope of similar studies carried out by the authors for cold-formed (higher leg width-to-thickness ratios) steel angles with the same characteristics. After reviewing (i) the most relevant findings unveiled in the studies concerning hotrolled steel angles, including the role played by residual stresses in eroding their ultimate strength, and (ii) the available experimental and numerical failure load data, comprising fixed-ended and pin-ended columns with several geometries (cross-section dimensions and length) and reported by various researchers, the paper briefly addresses the mechanical reasoning behind an efficient DSM-based design approach proposed by the authors in the context of cold-formed steel (slender legs) short-to-intermediate angle columns. Then, the available failure load data is used to assess the quality of their estimates provided by this DSM design approach, including the determination of the corresponding Load and Resistance Factor Design (LRFD) resistance factors. It is shown that the proposed design approach can be also successfully applied to predict hot-rolled steel angle column failure loads, leading to LRFD resistance factors above the value currently prescribed, for compression member design, by the North American Specification (φc=0.85).

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Section: Merit Assessment Of the Dsm-based Design Approach For Hot-romentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

13.11: DSM design approach for hot‐rolled steel angle columns

2017

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“…Despite the very good ultimate strength prediction quality ensured by the above DSM-based design approach, it was felt that the existing expressions providing parameters a, b, c and d (see Eqs. (9) and (10)) were too complex for codification purposes. Therefore, it was decided to look for simpler expressions (preferably linear ones), but without sacrificing the quality of the failure load predictions.…”

Section: Dsm-based Design Approach For Ps Columnsmentioning

confidence: 99%

“…The proposed expressions constitute bilinear approximations of Eqs. (9) and their coefficients were selected through a "trial and error" procedure to ensure flexural-torsional ultimate strength predictions as accurate as possible. The best approximation was found to be…”

Section: Modification Of the Flexural-torsional Strength Curves -Paramentioning

confidence: 99%

Design of simply supported hot‐rolled steelshort‐to‐intermediate angle columns

2019

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Selected, extended paper from the SDSS 2019 special session ECCS/TC8 – Structural Stability This work reports on the results of an ongoing investigation of the direct strength method (DSM) design of hot‐rolled steel equal‐leg angle columns with pinned (spherically hinged) supports and short‐to‐intermediate lengths, i.e. buckling in flexural‐torsional modes. It extends the scope of similar studies involving cold‐formed steel angle columns with the same characteristics (but higher leg width‐to‐thickness ratios). After collecting the experimental and numerical failure loads available in the literature concerning columns with several geometries, the paper addresses the mechanical reasoning behind a DSM‐based design approach proposed in the context of fixed‐end and cylindrically hinged cold‐formed and hot‐rolled steel short‐to‐intermediate angle columns, which must be modified to handle spherically hinged supports. After that, the failure loads gathered are used to assess the quality of their estimates using this design approach, namely, by determining LRFD resistance factors. It is shown that this approach can be successfully applied to predict hot‐rolled steel simply supported angle column failure loads, leading to LRFD resistance factors above 0.90.

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“…Although the non-linear behaviour, strength and design of angle columns has attracted a lot of attention for decades (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14]), it was not until the last few years that the mechanics underlying the column non-linear behaviour were unveiled and properly understood [15,16] and it became clear why the current North American Specification (NAS) for Cold-Formed Steel Structures [17] still excludes short-to-intermediate equal-leg angle columns from (i) the pre-qualification for the Direct Strength Method (DSM) design and (ii) the application of the LFRD resistance factor / = 0.85, valid for all other cold-formed steel compression members. It was found that, although such columns buckle in flexural-torsional modes associated with a critical load plateau, the corresponding post-critical strength reserve changes considerably along that same plateau, thus affecting significantly the column failure load.…”

Section: Introductionmentioning

confidence: 99%