<p lang="en-GB">An upper limit on the ratio of the yield strength to the tensile strength (Y/T ratio) is present in various maritime and civil structural design rules for steel structures as a requirement for designing for ductile behaviour in areas where plastic strains are expected to occur. In other instances, the design yield stress to be adopted in strength calculations is reduced from its nominal value if the Y/T ratio exceeds a certain limit. These provisions restrict the use of high strength steels which inherently have a high Y/T ratio. To guide subsequent efforts towards optimised Y/T limits and wider use of high strength steels, this study presents an overview of the current provisions in engineering practice and relates the reasons for the Y/T limit to underlying failure mechanisms. The key failure mechanisms identified are tensile strain localization leading to plastic instability, general yielding precipitated by stress concentrations, localization of plastic bending hinges and ductile fracture. Furthermore, the importance of the Y/T ratio is highlighted in different contexts and related to the uniform elongation, failure strain, and structural configurations such as are seen in cranes, ship hulls, building frames, and steel-to-steel connections. The reasoning behind the current provisions and the approaches used in previous assessments of the limits are highlighted.</p>

Failure Modes and Rules Related to the Yield-to-Tensile Strength Ratio in Steel Structures

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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