The first step in the calculations

The first step in the calculations is to find the initial strain, Ɛo, that is present in the extreme fiber of the cross section when the strengthening operations take place. This strain is the result of a moment Mo (service moment, no load safety factors are applied) acting at the critical cross section during strengthening (e.g. due to the self-weight of the structure and any additional load acting at the time of the strengthening), and may be calculated based on equilibrium of internal forces and moments (Fig. 2-4).