![]() ![]() ![]() However, although rolling increases the strength, it also reduces the ductility of the steel. This effect is readily apparent in material standards, which specify reducing levels of minimum yield strength with increasing material thickness. The more steel is rolled, the stronger it becomes. This rolling is the mechanical working that refines the grain structure and determines the mechanical properties. Plates and sections are produced by rolling steel slabs, blooms or billets (at a high temperature) until the required plate or section size is achieved. Hence, the chemical composition for each steel specification has been carefully chosen to achieve the required properties. Keeping the sulphur level low can enhance the ductility, and the toughness can be improved by the addition of Nickel. However, such alloy additions increase the cost of the steel, and can adversely affect other properties (i.e. Adding alloys such as Carbon, Manganese, Niobium and Vanadium can increase the strength. The chemical composition is fundamental to the mechanical properties of steel. Steel derives its material properties from a combination of chemical composition, mechanical working and heat treatment. 4.2 Identification, inspection documents and traceability.2.2.6 Design values of material coefficients. ![]() This article provides designers with background information and specific guidance on how to select an appropriate steel grade and quality, and on how the structural steel products for a bridge are specified in accordance with the Structural Eurocodes. The selection of an appropriate grade of steel for a bridge requires an awareness of the steel manufacturing process, an appreciation of the relevant product standards and design specifications, and an understanding of several issues including material properties, availability and cost. All these aspects of steel material are utilised by the designer of a steel bridge. ![]() Structural steel generally responds in a linear elastic manner, up to the ‘yield point’ and thereafter has a significant capacity for plastic straining before failure. In the structure, the material is subject to tensile and compressive forces. For structural use in bridges these products are inevitably cut (to size and shape) and welded, one component to another. Steel material is supplied in two product forms – ‘flat products’ (steel plate and strip) and ‘long products’ (rolled sections, either open beams, angles, etc or hollow sections). ![]()
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