Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams

Jun Ye, Seyed Mohammad Mojtabaei, Iman Hajirasouliha, Paul Shepherd, Kypros Pilakoutas

Research output: Contribution to conferencePaper

Abstract

This paper develops a numerical model to investigate the flexural strength and failure modes of CFS back-to-back channel beams and verifies the efficiency of an optimisation framework previously proposed. The model incorporates non-linear stress-strain behaviour and enhanced corner properties obtained from coupon tests, as well as initial geometric imperfections measured in physical specimens. To simulate the behaviour of a bolt bearing against a steel plate in the back-to-back section, a connector model is used that takes into account both slippage and bearing deformations. The developed Finite Element (FE) models are verified against six four-point bending tests on CFS back-to-back channel beams, where excellent agreement is found between the experimental results and the FE predictions. The validated FE models are then used to assess the adequacy of the effective width method in EC3 and the Direct Strength Method (DSM) in estimating the design capacity of conventional and optimum design CFS channel beam sections. The results indicate that both EC3 and DSM provide accurate predictions for the bending capacity of lipped channel beam sections. A comparison between FE predictions and tested results show that, on average, the geometric imperfections can change the FE predictions of ultimate capacity by up to 11%, while the strain-hardening of CFS material at the round corners has negligible effects. It is also shown that EC3 uses a reduced cross-sectional property to calculate deflections, which can reasonably predict deflections with a slight overestimation (6%) at the serviceability load level.
Original languageEnglish
Publication statusPublished - 24 Jul 2018
EventInternational Conference on Thin-Walled Structures - Instituto Superior Tecnico Congress Centre, Lisbon, Portugal
Duration: 24 Jul 201827 Jul 2018
Conference number: 8
http://ictws2018.ist.utl.pt/

Conference

ConferenceInternational Conference on Thin-Walled Structures
Abbreviated titleICTWS2018
CountryPortugal
CityLisbon
Period24/07/1827/07/18
Internet address

Keywords

  • Cold-formed Steel
  • Beam
  • Finite Element
  • Strength
  • Deflection

Cite this

Ye, J., Mojtabaei, S. M., Hajirasouliha, I., Shepherd, P., & Pilakoutas, K. (2018). Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams. Paper presented at International Conference on Thin-Walled Structures, Lisbon, Portugal.

Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams. / Ye, Jun; Mojtabaei, Seyed Mohammad; Hajirasouliha, Iman; Shepherd, Paul; Pilakoutas, Kypros.

2018. Paper presented at International Conference on Thin-Walled Structures, Lisbon, Portugal.

Research output: Contribution to conferencePaper

Ye, J, Mojtabaei, SM, Hajirasouliha, I, Shepherd, P & Pilakoutas, K 2018, 'Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams' Paper presented at International Conference on Thin-Walled Structures, Lisbon, Portugal, 24/07/18 - 27/07/18, .
Ye J, Mojtabaei SM, Hajirasouliha I, Shepherd P, Pilakoutas K. Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams. 2018. Paper presented at International Conference on Thin-Walled Structures, Lisbon, Portugal.
Ye, Jun ; Mojtabaei, Seyed Mohammad ; Hajirasouliha, Iman ; Shepherd, Paul ; Pilakoutas, Kypros. / Verification of Eurocode Design Models on the Calculation of Strengths and Deflections in Cold-Formed Steel Beams. Paper presented at International Conference on Thin-Walled Structures, Lisbon, Portugal.
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N2 - This paper develops a numerical model to investigate the flexural strength and failure modes of CFS back-to-back channel beams and verifies the efficiency of an optimisation framework previously proposed. The model incorporates non-linear stress-strain behaviour and enhanced corner properties obtained from coupon tests, as well as initial geometric imperfections measured in physical specimens. To simulate the behaviour of a bolt bearing against a steel plate in the back-to-back section, a connector model is used that takes into account both slippage and bearing deformations. The developed Finite Element (FE) models are verified against six four-point bending tests on CFS back-to-back channel beams, where excellent agreement is found between the experimental results and the FE predictions. The validated FE models are then used to assess the adequacy of the effective width method in EC3 and the Direct Strength Method (DSM) in estimating the design capacity of conventional and optimum design CFS channel beam sections. The results indicate that both EC3 and DSM provide accurate predictions for the bending capacity of lipped channel beam sections. A comparison between FE predictions and tested results show that, on average, the geometric imperfections can change the FE predictions of ultimate capacity by up to 11%, while the strain-hardening of CFS material at the round corners has negligible effects. It is also shown that EC3 uses a reduced cross-sectional property to calculate deflections, which can reasonably predict deflections with a slight overestimation (6%) at the serviceability load level.

AB - This paper develops a numerical model to investigate the flexural strength and failure modes of CFS back-to-back channel beams and verifies the efficiency of an optimisation framework previously proposed. The model incorporates non-linear stress-strain behaviour and enhanced corner properties obtained from coupon tests, as well as initial geometric imperfections measured in physical specimens. To simulate the behaviour of a bolt bearing against a steel plate in the back-to-back section, a connector model is used that takes into account both slippage and bearing deformations. The developed Finite Element (FE) models are verified against six four-point bending tests on CFS back-to-back channel beams, where excellent agreement is found between the experimental results and the FE predictions. The validated FE models are then used to assess the adequacy of the effective width method in EC3 and the Direct Strength Method (DSM) in estimating the design capacity of conventional and optimum design CFS channel beam sections. The results indicate that both EC3 and DSM provide accurate predictions for the bending capacity of lipped channel beam sections. A comparison between FE predictions and tested results show that, on average, the geometric imperfections can change the FE predictions of ultimate capacity by up to 11%, while the strain-hardening of CFS material at the round corners has negligible effects. It is also shown that EC3 uses a reduced cross-sectional property to calculate deflections, which can reasonably predict deflections with a slight overestimation (6%) at the serviceability load level.

KW - Cold-formed Steel

KW - Beam

KW - Finite Element

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