PSI - Issue 84

D. Di Fiore et al. / Procedia Structural Integrity 84 (2026) 159–166

164

Table 1. Impact on structural performance

Upgrade on SGG condition

Upgrade on SLO condition

New deterioration model

To do nothing

-

-

- -

IMS IRS TRS

+ 25 % + 55 %

+ 25 % + 55 %

IRS deterioration TRS deterioration

= 100 % (as new)

= 100 % (as new)

Initially, the interventions are applied without considering a repetition or extraordinary maintenance in the future. In this scenario, the aim is to assess how many segments reach a condition ≤20% of the original theoretical performance within the time frame analysed. Subsequently, the interventions are repeated, or extraordinary maintenance is carried out, to prevent performance falling below the minimum threshold. The trigger for subsequent treatments is user-defined, typically to maintain a minimum level of structural performance of at least 20% of the original theoretical performance. However, it can also be defined according to other engineer's objectives. The main outcome is an estimation of the direct and indirect additional cost required to meet the minimum structural performance requirements for each segment within the analysed timeframe. 3. Economics, duration and sustainability 3.1. Economics of the solutions One of the key factors of lifecycle cost analysis is the time value of money. In economic decision-making, people value near-term revenue and near-term cost more highly than money that changes hands in the futures. The mathematical formulas for computing lifecycle cost are well known in asset management applications. The discount factor is calculated from (1). ( ) = (1+ 1 ) ≈ (− ∙ ) ≪ 1 (1) Where i is the real discount rate and t the number of years from the instant we want to evaluate different scenarios. In Fig. 6 the representation of the discount factor for different discount rate.

Fig. 6. Discount factor for different discount rates vs time

In order to compute the net present value (NPV) of future investments, costs (CapEx and OpEx) and benefits for each treatment scenario are discounted to Time = 0.