PSI - Issue 38

B. Depale et al. / Procedia Structural Integrity 38 (2022) 317–330 B. Depale – M. Bennebach/ Structural Integrity Procedia 00 (2021) 000 – 000

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- Phase 5: Evaluation of residual life Residual life is evaluated for the various operational scenarios retained, using updated or modern rules/references, with a clear separation in the analysis between the past operations and the future expected ones. The severity of the critical areas and defects reported is also highlighted. The fatigue strength of constructional details may be decreased compared to their theoretical values from standards when the quality of execution has been reported as bad from the Phase 3.2 inspection. Whilst there are many engineers practicing Finite Element Analysis not so many are able to execute correctly a proof of fatigue strength. This is more critical in residual life estimation because the fatigue proofs in many standards are for design purpose only, and not appropriate when it is necessary to deal with residual life and consumed life. Phase 6: Extension or not of Service life The final report is delivered with all results and assumptions, from all previous Phases, all remedial measures and period until next evaluation and updated inspection planning. Pragmatism is the keyword for this phase, because if the assessment of equipment results in the extension of service lifetime instead of its service being terminated, it may be a combination of: - Repairs, - Proposal of inspection plan, with local focus on critical areas that can have different inspection periods (which will be adapted by site feedback), - Installation of cycles counters (black boxes) or strain gauges (usage monitoring), - Declassification/derating (decrease of the rated load for a crane, for example). 6 An example for cranes: loading bridges of Calais harbour The purpose of this 2006 study has been to estimate the residual life of many loading bridges of the French Channel harbor of Calais (France) as part of a continuing modernization program. The loading bridge presented hereafter consists of an articulated bridge (52 meters length) lifted by hoisting mechanisms, being themselves installed on a fixed portal frame (see Figure 2). The rated capacity equals 60 tons. It was installed in 1980 and the desire of Calais harbor has been to keep it in service until 2020. During Phase 1 (Preliminary evaluation), initial calculation reports have been studied and notably the assumptions made in the original proof of fatigue strength (Note de calculs, date 14.08.1979, plan n° 10, SCHMID VALENCIENNES, affaire n° 91.6402) . Then a first set of distributions of vehicles on the bridge have been established from available traffic records and working cycles of the devices, thanks to a close collaboration with the Calais harbor service activities, for the past duty (reported in Excel files). No major modification of the initial structures and mechanisms was reported, and the maintenance program had been fully applied. In that step, it may be necessary to deal with risk acceptance criteria. In that phase, it may be necessary to deal with risk acceptance criteria. -