Structural behaviour of lean duplex stainless steel welded I-sections

Abstract

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.