Browsing by Author "Bradford, MA"

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    Investigation of residual stresses distribution in high strength steel beams using neutron diffraction
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Le, T; Paradowska, AM; Bradford, MA
    Residual stresses induced in the fabrication of steel components may lead to distortion and a significant loss of strength in a steel structure. Accordingly, research on the residual stress distribution in steel sections is becoming an important consideration in steel structural analysis. The characteristics of residual stresses in hot-rolled and welded mild steel sections have been extensively reported and integrated in national design standards. However, it is questionable as to whether such patterns are applicable for high strength steel. Currently, very high strength low-alloy steels produced by quenching-tempering and thermo-controlled processes offer yield strengths as high as 1000 MPa with good weldability, and because of this they have been receiving much attention in mega-structure applications such as long-span bridges or high-rise buildings. To promote the use of such materials, knowledge of welding residual stresses is vital. This study presents the measurement of residual stresses in I-beam sections welded from Australian BISPLATE80 and BISPLATE100 high strength steel using neutron diffraction technique. Tensile coupon testing shows the base plate materials have corresponding yield stresses of 851 MPa and 1003 MPa respectively, with the weld material yield strength as high as 810 MPa. The residual stress measurement was taken on the KOWARI strain scanner at ANSTO. Due to the complexity and the large size of samples the SSCANSS software and a virtual instrument of KOWARI were utilised to position a sample and optimise the measurement procedure. Important features of the residual stress distribution in welded high strength steel I-sections have been obtained across the beam and within the weld. These results are the essential in order to validate a residual stress model able to be used in future high strength steel structural analysis, design and assessment. © The Authors.
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    Investigation of residual stresses distribution in high strength steel beams using neutron diffraction
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11) Le, T; Bradford, MA; Paradowska, AM
    Residual stresses induced in the fabrication of steel components may lead to distortion and a significant loss of strength in a steel structure. Accordingly, research on the residual stress distribution in steel sections is becoming an important consideration in steel structural analysis. The characteristics of residual stresses in hot-rolled and welded mild steel sections have been extensively reported and integrated in national design standards. However, it is questionable as to whether such patterns are applicable for high strength steel. Currently, very high strength low-alloy steels produced by quenching-tempering and thermo-controlled processes offer yield strengths as high as 1000 MPa with good weldability, and because of this they have been receiving much attention in mega-structure applications such as long-span bridges or high-rise buildings. To promote the use of such materials, knowledge of welding residual stresses is vital. This study presents the measurement of residual stresses in I-beam sections welded from Australian BISPLATE80 and BISPLATE100 high strength steel using neutron diffraction technique. Tensile coupon testing shows the base plate materials have corresponding yield stresses of 851 MPa and 1003 MPa respectively, with the weld material yield strength as high as 810 MPa. The residual stress measurement was taken on the KOWARI strain scanner at ANSTO. Due to the complexity and the large size of samples the SSCANSS software and a virtual instrument of KOWARI were utilised to position a sample and optimise the measurement procedure. Important features of the residual stress distribution in welded high strength steel I-sections have been obtained across the beam and within the weld. These results are the essential in order to validate a residual stress model able to be used in future high strength steel structural analysis, design and assessment.
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    Residual stresses in welded high-strength steel I-Beams
    (Elsevier B. V., 2020-04) Le, T; Paradowska, AM; Bradford, MA; Liu, XP; Valipour, HR
    This study investigates a unified residual stress model applicable for welded high-strength steel (HSS) I-beams. In the experimental program, the homogeneous specimens including two prismatic I-beam samples and a web-tapered I-beam fabricated from Australian BISPLATE-80 and BISPLATE-100 steel plates having nominal yield stresses of 690 MPa and 890 MPa respectively were inspected to determine their residual stress distribution using a non-destructive neutron diffraction technique. Details of this neutron diffraction method for measuring residual stresses are presented. It is shown that the technique can achieve high spatial resolution of the residual stresses as well as capturing the high stress gradient in the heat-affected zone, as a consequence of the deep penetration of the neutron particles into the material. The pattern of residual stresses in the specimens reveals that the tensile stresses peak at the flange-web junctions at an average of 70% of the parent material yield stresses, and that the compressive residual stresses have an approximately uniform distribution that dominates large regions of the flange and web. The test results reconfirm the compressive residual stresses being related to the geometry of the cross-section and independent of the steel grade. The interaction of the residual stresses in the flanges and web was found to be negligible for both prismatic and web-tapered beams. A residual stress model applicable for welded thin-walled I-section members for steel grades between 460 MPa and 1000 MPa is proposed by fitting the test results and collective data available in the literature. This representation was incorporated into a detailed finite element (FE) model and it is shown that the FE predictions are in good agreement with the results of experiments conducted on a wide range of HSS I-section beams tested to failure caused by buckling and/or yielding. ©2019 Published by Elsevier Ltd.