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Title: Structural behaviour of laser-welded stainless steel I-sections
Author: Bu, Yidu
ISNI:       0000 0004 7657 8116
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2018
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Stainless steel structures have been increasingly used in engineering applications because of its corrosion resistance, aesthetic appeal, favourable structural properties as well as the development of stainless steel guidance. While the structural response of cold-formed stainless steel sections has been extensively studied in the literature, welded sections have received less attention to date. A recent addition to the range of structural stainless steel products is that of laser-welded sections. Owing to the high precision and low heat input of the fabrication process, the resulting sections have smaller heat affected zones, lower thermal distortions and lower residual stresses than would typically arise from traditional welding processes. There currently exists very limited experimental data on laser-welded stainless steel members owing to their recent introduction to the construction industry and their design is not covered by current design standards. To address the lack of test data and to investigate their structural response, a comprehensive experimental programme has been carried out covering complementary residual stress measurements, 9 stub column tests, 20 bending tests and 24 combined loading tests at the cross-sectional level, as well as 22 flexural buckling tests and 18 beam-columns at the member level. The derived test results were then employed in the numerical studies where the numerical models were first validated against the test results and then used to conduct a series of parametric studies to generate further data over a wider range of cross-sectional slendernesses, member slendernesses and loading combinations. The test and numerical results were used to assess the current design provisions and it was found that the design codes yield conservative predictions due to the neglect of strain hardening. Revised design rules have been proposed, offering less scattered, more accurate predictions for conventionally welded members and, for the first time, design provisions for laser-welded members.
Supervisor: Gardner, Leroy Sponsor: China Scholarship Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral