Behaviour and design of high-performance steel welded I-section structural components
High-performance steels, including stainless steels and high strength steels, have been gaining increasing attention in civil engineering, owing to their appealing sustainable and mechanical advantages. The present thesis is focusing on the behaviour and design of high-performance steel welded I-sec...
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| Format: | Thesis-Doctor of Philosophy |
| Language: | English |
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Nanyang Technological University
2021
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| Online Access: | https://hdl.handle.net/10356/149425 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | High-performance steels, including stainless steels and high strength steels, have been gaining increasing attention in civil engineering, owing to their appealing sustainable and mechanical advantages. The present thesis is focusing on the behaviour and design of high-performance steel welded I-section structural components. A comprehensive testing programme was firstly conducted, which adopted twelve welded I-sections made of two types of high-performance steel (grade EN 1.4420 high-chromium stainless steel and S690 high strength steel). Material testing was carried out to derive the material stress–strain responses of the two adopted high-performance steel grades, and membrane residual stress measurements were performed to determine the membrane residual stress distributions and amplitudes in the studied high-performance steel welded I-sections. At the cross-sectional level, a total of 24 axially loaded stub column tests, 20 in-pane four-point bending tests, and 10 eccentrically loaded stub column tests were conducted to investigate the cross-section resistances and local stability of high-performance steel welded I-sections. At the member level, 40 column tests and 10 beam-column tests were performed to study the load-carrying capacities and member instability of high-performance steel welded I-sections. The testing programme was supplemented by a numerical modelling programme, where finite element models were firstly developed and validated against the test results and then employed to perform a series of numerical parametric studies to generate additional numerical data over a wide range of cross-section dimensions, member lengths and loading combinations. The obtained test and numerical results were used to evaluate (i) the applicability of the current design codes for normal stainless steel members to the new high-chromium stainless steel welded I-section members and (ii) the accuracy of the existing relevant design codes for S690 high strength steel welded I-section members. The evaluation results generally indicated that the current design codes result in inaccurate resistance predictions, mainly owing to the lack of due consideration of the specific material characteristics of the two types of high-performance steel. New design methods have also been proposed, which were shown to provide substantially improved design accuracy and consistency over the existing design standards. The reliability of the proposed design methods has been confirmed by means of statistical analyses, demonstrating their suitability for incorporation into future revisions of international design codes for stainless steel and high strength steel structures. |
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