Material properties and shear behaviour of QN1803 high-strength stainless steel plate girders

Abstract

QN1803, a high-strength stainless steel, has been developed recently, and its tensile yield strength can be approximately 40 % (or more) higher than the commonly-used EN1.4301, while its cost is 20 % lower due to its reduced nickel content. This high-performance material can potentially be used in many applications, and one such application is plate girders. However, no experimental work has been undertaken. This issue is addressed herein. A detailed experimental study comprising seven plate girder tests is presented in this study. The plates were austenitic grade QN1803 and EN 1.4301, and the depth of web was fixed as 500 mm, 600 mm and 700 mm. For comparison, specimens with rigid end posts were also tested. The initial geometrical imperfections were first determined from three-dimensional (3D) scanning. Finite element models (FEMs) incorporating the material non-linearity and initial geometric imperfections are then developed and validated against the test results. A total of 15 tensile coupon tests are performed to investigate the effects of rolling directions on the material properties, with longitudinal coupons, diagonal coupons, and transverse coupons all being tested. The test results indicated that the 0.2 % proof stresses of the transverse coupons were approximately 8.5 % higher than that of the longitudinal coupons. The plate girder tests suggested that the shear buckling strength of QN1803 members was increased by 38.2 % on average compared to EN 1.4301 members. The design rules for determining the shear buckling strength of plate girders as provided in Eurocodes (EN 1993–1–4 +A1) (2015), North American Specification (ANSI/AISC 370–21) (2021) and those proposed by Chen et al. (2023) were evaluated. The results demonstrated that the design formulas proposed by Chen et al. (2023) can closely calculate the shear buckling strength of such QN1803 members.