Toughness of old mild steels

Abstract

For the rehabilitation of steel structures from the 19th and the early 20th century the brittle fracture behaviour is essential for the structural safety. The methods of the assessment used in EN 1993-1-10 were predominantly developed for welded structures made of current steel grades with more or less high toughness. The check by limitation of the plate thickness is not suitable for old mild steel structures with riveted and bolted connections. Notch effects and residual stresses are quite different to those ones of welded structures. The material properties of old mild steels are characterised by larger scatters, particularly due to the inhomogeneous distribution of tramp elements and higher contents of non-metallic inclusions. In this paper, experimental and analytical studies of the brittle fracture behaviour of mild steels as well as aging effects of structural elements with holes for riveted and bolted connections are presented.