تست، شبیه سازی و طراحی فولاد ضدزنگ لیزری جوش داده شده
Abstract
1- Introduction
2- Experimental investigation
3- Numerical modelling
4- Discussion and assessment of current design methods
5- New design proposal
6- Conclusions
References
Abstract
The stability and design of laser-welded stainless steel I-section beam-columns are explored in this study. Owing to the high precision and low heat input of laser-welding, structural cross-sections produced using this fabrication method have smaller heat affected zones, lower thermal distortions and lower residual stresses than would typically arise from traditional welding processes. Eighteen laser-welded stainless steel beam-columns were tested to investigate the member buckling behaviour under combined compression and bending. Two I-section sizes were considered in the tests: I-50 × 50 × 4 × 4 in grade EN 1.4301 and I-102 × 68 × 5 × 5 in grade EN 1.4571 austenitic stainless steel. The two cases of minor axis bending plus compression and major axis bending plus compression with lateral restraints were investigated. The initial loading eccentricities in the beam-column tests were varied to provide a wide range of bending moment-to-axial load ratios. The test results obtained herein and from a previous experimental study were used to validate finite element (FE) models, which were subsequently employed for parametric investigations to generate further structural performance data over a wider range of cross-section sizes, member lengths and loading combinations. The obtained test and FE results were utilized to evaluate the accuracy of the beam-column capacity predictions according to the current European and North American design provisions and a recent proposal by Greiner and Kettler. Finally, an improved approach for the design of stainless steel I-section beam-columns is proposed.
Introduction
Stainless steel is becoming increasingly used in the construction industry owing to its corrosion resistance, aesthetic appeal, favourable structural properties and a range of other beneficial characteristics. A recent addition to the stainless steel product range is that of laserwelded sections. Laser-welding is a fabrication method which uses lasers to locally melt and fuse together individual metallic elements into a range of complete structural sections without the use of filler material. Compared to conventional arc welding, laser-welding enables the heat input to be kept to a minimum, and thus leads to lower thermal distortions and residual stresses. Since their recent introduction to the construction industry, there has only been some initial research [1–4] into the structural behaviour of laser-welded stainless steel sections, and their design is not explicitly covered in current structural design provisions. The design of beam-column members generally features interaction formulae, with the bending moment resistance and compressive member resistance as end points. Previous research has been carried out into the behaviour and cross-section resistance of stainless steel Isections in bending [5–11] and the member buckling behaviour of stainless steel I-section members in compression [7,12–15]. Research has been performed on stainless steel beam-columns, but focussing on hollow sections [16–19], while studies and data on I-section beamcolumn are scarce. In 2000, Burgan et al. [7] conducted eight stainless steel welded I-section beam-column tests under compression and major axis bending. More recently Zheng et al. [16] carried out five stainless steel welded I-section beam-column tests with different buckling lengths to investigate their global stability.