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  • Imperfection amplitudes for nonlinear analysis of open thin-walled steel cross-sections used in rack column uprights

     Pastor Artigues, M. Magdalena; Casafont Ribera, Miquel; Bonada Bo, Jordi; Roure Fernandez, Francisco
    Thin-walled structures
    Date of publication: 2014-03-01
    Journal article

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    When numerical models are used to predict behaviour of open thin-walled steel cross-sections, the nonlinear analysis results can be influenced by the magnitudes introduced as initial imperfection. At present, a wide range of values is considered in research concerning this topic. This paper explores up to what point the nonlinear analysis results are sensitive to the choice of imperfection magnitudes and attempt to refine the spectrum of magnitudes that should be used. The study focuses on rack uprights (with and without perforations) under compression and the numerical model has been validated with experimental tests conducted by the authors. Three different column lengths have been selected to reproduce a mainly local, distortional and global failure mode, so that coupled instabilities have not to be considered in this case. The results show that the ultimate load and collapse mode are both sensitive to imperfection amplitude, mainly in the case of distortional buckling. (C) 2013 Elsevier Ltd. All rights reserved.

  • Anàlisi del comportament a compressió de perfils prims oberts d'acer conformats en fred

     Bonada Bo, Jordi
    Defense's date: 2014-01-23
    Universitat Politècnica de Catalunya
    Theses

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    Els perfils prims oberts d'acer conformats en fred són elements estructurals molt utilitzats en les prestatgeries per a emmagatzematge de palets. Aquests perfils són habitualment emprats com a columnes i contenen perforacions uniformement distribuïdes per garantir la connexió entre els diferents elements estructurals. Un dels motius més freqüents de fallida d'aquestes prestatgeries és el col·lapse a compressió dels puntals, i per tant, la determinació de la seva capacitat resistent és un factor clau per assegurar el correcte dimensionament de l'estructura. Els perfils prims conformats en fred, a diferència dels elements estructurals conformats en calent (IPN, IPE, HEB, etc), presenten una sensibilitat molt més elevada als modes de vinclament local i distorsional a causa de les seves característiques geomètriques. La inclusió d'aquests modes complica considerablement el procés de càlcul resistent, ja que les teories clàssiques de barres no tenen en compte les deformacions seccionals. Com a conseqüència, el desenvolupament de nous mètodes i les anàlisis mitjançant elements finits han cobrat una gran importància. Nombroses investigacions actuals tenen com a objectiu l'adquisició de nous coneixements sobre el comportament a compressió dels perfils prims que permetin millorar les normatives de càlcul vigents. Alguns dels aspectes on més s'està aprofundint són: la interacció dels diferents modes de fallida, el tipus d'imperfecció geomètrica a utilitzar en les anàlisis per elements finits, l'efecte de l'enduriment per deformació, l'obtenció de les tensions residuals i la importància d'aquestes en la capacitat resistent del puntal i la caracterització de les perforacions en els diferents mètodes de càlcul. La present tesi doctoral pretén aportar nous coneixements en alguns dels factors prèviament mencionats. S'ha estudiat l'efecte de l'enduriment per deformació, les tensions residuals i la modelització del problema d'estudi mitjançant el mètode dels elements finits verificant els valors obtinguts amb resultats experimentals sempre que hagi estat possible. També s'ha desenvolupat un programa per calcular càrregues elàstiques de vinclament per a qualsevol tipus de mode de fallida, ja que aquesta informació és necessària pels càlculs utilitzant la normativa i també per alguna de les metodologies de càlcul proposades mitjançant la simulació numèrica. Paraules clau: Perfil prim obert, rack, imperfecció geomètrica, vinclament distorsional, GBT, tensions residuals, enduriment per deformació, anàlisi per elements finits.

  • Determination of beam-to-column connection characteristics in pallet rack structures: a comparison of the EN and ANSI methods and an analysis of the influence of the moment-to-shear ratios

     Roure Fernandez, Francisco; Somalo Coarasa, Maria Rosa; Casafont Ribera, Miquel; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Peköz, Teoman
    Steel Construction
    Date of publication: 2013-05-14
    Journal article

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    The beam-to-column connections in most of the pallet rack structures made of thin-walled steel sections are of the clip-on type. These connections are of a semi-rigid nature and have a non-linear moment¿rotation relationship, which has to be determined experimentally. The experimental methods described in the European standard (EN 15512: 2009) and the American standard (ANSI MH 16.1: 2008) are different. This paper presents a series of test results determining the beam-to-column connection characteristics of European and American origin, tested with both methods. This is followed by a comparison and analysis of the results. The influence of the distance from the applied load to the face of the upright, i.e. the influence of the moment-to-shear ratio, is also analysed and discussed.

    he beam-to-column connections in most of the pallet rack structures made of thin-walled steel sections are of the clip-on type. These connections are of a semi-rigid nature and have a non-linear moment–rotation relationship, which has to be determined experimen - tally. The experimental methods described in the European standard (EN 15512: 2009) and the American standard (ANSI MH 16.1: 2008) are different. This paper presents a series of test results determining the beam-to-column connection characteristics of European and American origin, tested with both methods. This is followed by a comparison and analysis of the results. The influence of the distance from the applied load to the face of the upright, i.e. the influence of the moment-to-shear ratio, is also analysed and discussed

  • Residual stresses and initial imperfections in non-linear analysis

     Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Roure Fernandez, Francisco; Casafont Ribera, Miquel
    Engineering structures
    Date of publication: 2013-01
    Journal article

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    When non-linear finite element analysis (FEA) of cold-formed thin-walled steel sections subject to compression is carried out, an initial perturbation must be introduced in the model in order to trigger the failure due to instability. The most usual way is to introduce an equivalent initial imperfection in the model (conventional models) that includes the effects of geometric imperfections and residual stresses due to the roll-forming manufacturing process, possible loading eccentricity, etc. It is thought that results would be more accurate if the actual measured geometric imperfections and the actual residual stresses induced from manufacturing were introduced. This paper presents the determination of residual strains and stresses generated in the cold roll-forming process of a typical rack section (without perforations) from steel sheet, using FE simulation. The obtained residual elastic and plastic strains have then been incorporated in the model, and used as an initial strain state in the non-linear finite element analysis. The results obtained agree well with the experimental results for short and intermediate length columns, where the failure mode is predominately local and distortional.

  • Distortional buckling test for steel storage rack columns

     Casafont Ribera, Miquel; Roure Fernandez, Francisco; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Peköz, Teoman
    Proceedings of the Institution of Civil Engineers. Structures and buildings
    Date of publication: 2013-09
    Journal article

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    An investigation into the test method for distortional buckling of steel storage rack columns is presented. The main problem of the experimental method is to determine the length of the samples to be tested. The paper proposes to solve this problem by performing linear buckling analysis of the columns. Nowadays, linear buckling analysis can be easily carried out by practical designers with the help of newly developed programs based on the finite strip method and generalised beam theory. A simple test procedure is presented and validated in an experimental campaign on four different perforated rack columns. The tests also made it possible to observe the buckling behaviour of such columns, which involves a combination of different buckling modes.

  • Design of perforated industrial storage rack columns for distortional buckling

     Peköz, Teoman; Kiymaz, Guven; Casafont Ribera, Miquel; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi
    International Specialty Conference on Cold-Formed Steel Structures
    Presentation's date: 2012-10
    Presentation of work at congresses

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  • The influence of residual stresses on the buckling behaviour of rack uprights

     Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Roure Fernandez, Francisco; Casafont Ribera, Miquel
    International Conference on Computational Structures Technology
    Presentation's date: 2012-09-04
    Presentation of work at congresses

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  • Experimental measurements and numerical analysis of roll-forming residual stresses in a pallet rack upright

     Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Roure Fernandez, Francisco; Casafont Ribera, Miquel
    Symposium for Manufacturing in the Euroregion
    Presentation's date: 2012-06-07
    Presentation of work at congresses

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  • Linear buckling analysis of perforated steel storage rack columns with the Finite Strip Method

     Casafont Ribera, Miquel; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Roure Fernandez, Francisco; Peköz, Teoman
    Thin-walled structures
    Date of publication: 2012-12
    Journal article

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    An investigation on the use of the Finite Strip Method (FSM) to calculate elastic buckling loads of perforated cold formed storage rack columns is presented. Nowadays, this calculation can be accurately performed by means of the Finite Element Method (FEM), because the effect of perforations can be explicitly considered in the analysis. However, the FSM is preferred in cold-formed steel design since it is implemented in much convenient and easy to use software. The problem with FSM is that holes cannot be easily modeled. In this paper, the concept of the reduced thickness of the perforated strip is applied to take into account their effect. A formulation is presented for the reduced thickness that has been calibrated with loads obtained in eigen-buckling FEM analyses. Its accuracy has been verified carrying out analyses on real rack columns with different end conditions

  • An investigation on the design of steel storage rack columns via the direct strength method

     Casafont Ribera, Miquel; Pastor Artigues, M. Magdalena; Roure Fernandez, Francisco; Bonada Bo, Jordi; Peköz, Teoman
    Journal of structural engineering (New York, N.Y.)
    Date of publication: 2012-04-11
    Journal article

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    The paper presents an attempt to predict the load carrying capacity of perforated rack columns by means of the Direct Strength Method (DSM). The investigation is focused on two different issues: the prediction of the elastic buckling loads of members with multiple perforations, and the evaluation of the accuracy of the current DSM buckling curves when applied to rack columns. In relation to the first issue, a model for the calculation of the reduced thickness of the perforated strip to be used in finite strip buckling analysis is developed. Regarding the study of the DSM curves, it is demonstrated that they can be used to accurately determine the strength of rack cross-sections whose failure is governed by distortional buckling or global buckling (with no significant participation of local buckling). This is an interesting result because it will allow substituting the distortional buckling tests, that are currently carried out in the process of design of these columns, by a simple and easy to apply calculation procedure.

  • Fall Detector for the Elder

     Casafont Ribera, Miquel; Bonada Bo, Jordi; Pastor Artigues, M. Magdalena; Roure Fernandez, Francisco
    Participation in a competitive project

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  • Longitudinal strain distributions in rack uprights. Equivalent thickness

     Pastor Artigues, M. Magdalena; Roure Fernandez, Francisco; Casafont Ribera, Miquel; Bonada Bo, Jordi; Noguera Vich, Joan
    International Conference on Thin-Walled Structures
    Presentation's date: 2011-09-06
    Presentation of work at congresses

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  • Linear buckling analysis of perforated steel storage rack columns with the finite strip method

     Casafont Ribera, Miquel; Caparrós Martínez, Juan Francisco; Pastor Artigues, M. Magdalena; Roure Fernandez, Francisco; Bonada Bo, Jordi
    International Conference on Thin-Walled Structures
    Presentation's date: 2011-09-06
    Presentation of work at congresses

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  • Selection of the initial geometrical imperfection in nonlinear FE analysis of cold-formed steel rack columns

     Bonada Bo, Jordi; Casafont Ribera, Miquel; Roure Fernandez, Francisco; Pastor Artigues, M. Magdalena
    Thin-walled structures
    Date of publication: 2011-11-05
    Journal article

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  • An investigation on the desgin of steel storage rack columns by the Direct Strength Method

     Casafont Ribera, Miquel; Pastor Artigues, M. Magdalena; Roure Fernandez, Francisco; Bonada Bo, Jordi; Peköz, Teoman
    Date: 2011-10-11
    Report

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  • Fatigue tests on Connection of cross-aisle tie to upright (Preliminary results)

     Roure Fernandez, Francisco; Somalo Coarasa, Maria Rosa; Bonada Bo, Jordi
    Date: 2011-10-10
    Report

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  • Test method for distortional buckling of compressed pallet rack members. Length of specimens

     Casafont Ribera, Miquel; Roure Fernandez, Francisco; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi
    Date: 2011-12-15
    Report

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  • Perfiles metálicos con secciones abiertas de pared delgada

     Roure Fernandez, Francisco; Pastor Artigues, M. Magdalena; Bonada Bo, Jordi; Casafont Ribera, Miquel; Minguella Canela, Joaquim
    Deformación metálica
    Date of publication: 2011-04
    Journal article

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  • Influence of holes on the behaviour of cold-formed steel sections under compression

     Pastor Artigues, M. Magdalena; Casafont Ribera, Miquel; Roure Fernandez, Francisco; Bonada Bo, Jordi; Noguera Vich, Joan
    International Colloquium Stability and Ductility of Steel Structures
    Presentation's date: 2010-09-10
    Presentation of work at congresses

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  • Simulation of the Roll-Forming Process for the Determination of the Relevant Residual Stresses of Cold-Formed Steel Members

     Roure Fernandez, Francisco; Pastor Artigues, M. Magdalena; Casafont Ribera, Miquel; Bonada Bo, Jordi
    International Congress on Roll Forming
    Presentation's date: 2009-10-14
    Presentation of work at congresses

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