This paper reviews the definition of elastic follow-up starting with that used in creep assessments and seeking parallel
definitions for the treatment of combined primary and secondary loadings in fracture assessments. Methods for
estimating the elastic follow-up factor for secondary stresses acting alone in cracked structures are then presented. It
is shown that elastic follow-up factors can be estimated from elastic-plastic estimates of J for high secondary stress
and are weakly dependent on elastic-plastic material properties. Potential methods for estimating J under combined
primary and secondary loadings, using the elastic follow-up factor evaluated for secondary stresses acting alone, are
then presented. The applicability of these methods is examined in part 2 of this paper by comparison with detailed
finite element calculations.