WES 2808 for Brittle Fracture Assessment of Steel Components under Seismic Conditions – Part I: Fracture Assessment Procedure

After the Kobe Great Earthquake, by which a number of steel structures were damaged to a large extent, the welding engineering society (JWES) standard, WES 2808 was issued in 2003 in Japan for the assessment of brittle fracture in steel weldments subjected to large cyclic and dynamic strain. WES 2808 is characterized by two unique ideas: One is a reference temperature concept for fracture toughness evaluation under seismic conditions. Another is the CTOD toughness correction for constraint loss in steel components in large scale yielding, which is specified on the vasis of the Weibull stress criterion. Structural steels covered by WES 2808 were up to 600 MPa strength class. Recent industrial needs in Japan require the application of 780 MPa class steel to column components. Thereby, the revision of WES 2808 is under progress in JWES. This paper describes the fracture assessment procedure of WES 2808, which includes the influence of pre-strain and dynamic loading on the mechanical properties and CTOD fracture toughness of high strength steels, the evaluation of fracture toughness of steel HAZ after pre-straining, and the equivalent CTOD concept for collection of constraint loss in beam-to-column connections.