Despite growing interest in the use of stainless steel in the construction industry and
the development of a number of national and regional design codes, stainless steel is often
regarded as only suitable for specialised applications. This is attributed largely to the high
initial material cost associated with the most commonly adopted austenitic grades of stainless
steel, as well as some conservatism embedded in current stainless steel guidance. A recently
developed grade, known as lean duplex stainless steel (EN 1.4162), possesses higher strength than
the common austenitic grades and has a lower cost, along with good corrosion resistance and
adequate weldability and fracture toughness. The structural performance of lean duplex stainless
steel remains relatively unexplored to date with only a few studies having been performed. The main
aim of this study is to examine the structural behaviour of lean duplex stainless steel welded
I-sections, and to assess the applicability of the current European stainless steel design
guidance.

As part of this research, a total of fifty two material tests, four stub column tests, eight
3-point and 4-point bending tests, eight continuous beam tests and nine shear buckling tests were
carried out. The experimental programme was complemented by a parallel numerical investigation, in
which finite element models were initially validated against the test results and subsequently used
for parametric studies. These test and numerical results were used in conjunction with existing
test data on stainless steel welded I-sections to characterise the basic material properties,
assess the codified slenderness limits for cross-section classification, investigate the
applicability of plastic design to indeterminate stainless steel structures, and establish new
shear resistance design equations for stainless steel plate girders.

Based on the findings, it was concluded that the present European design provisions can be safely
applied to lean duplex but are rather conservative in some areas. To rectify this, modifications
have been proposed for cross-section classification, plastic design and shear resistance
calculations. These proposals, together with additional developments to the strain based continuous
strength method of design, are suitable
for incorporation into future revisions of Eurocode 3.