The right choice of steel – according to the Eurocode - Economical Bridge Solutions based on Innovative Composite Dowels and Integrated Abutments - page 20

2.3.2 The right choice of steel for toughness assessment

As introduced, it is essential for the safe use of structures designed according to Eurocode
3 that the material has a sufficient toughness to avoid brittle fracture of tension elements
exposed at the lowest service temperature expected to occur within the intended design life
of the structure. Rules for the selection of steels are therefore offered in Part 1-10 of EN 1993,
which allow a simple toughness assessment to avoid brittle fracture. The basis for the assess-
ment is a fracture mechanics approach with the design check for which the design values of
the action effect E d = K * appl,d (stress intensity factor) are compared to the design values of the
toughness resistance R d = K mat,d in the transition region of the impact energy - temperature
curve Kühn (2005) (“Fig. 17”) [6] thus as:

K* appl,d ≤ K mat,d (1)

Figure 17: Action side of the toughness assessment [7]

On the action side, K appl,d is determined for a certain flaw size, modeled by a surface
crack. However, the use of the stress intensity factor K appl,d is limited for an elastic fracture
mechanics approach and therefore needs to be corrected for plastic strains via the CEGB R6-
FAD Failure Assessment Diagram. Consequently, the toughness requirement for the steel is
given by the K * appl,d .