PSI - Issue 84

Sergio Belluco et al. / Procedia Structural Integrity 84 (2026) 607–614

614

Fig. 7. Comparison of the reliability index attained with the proposed formulations and with current code provisions for the CC2 case for the anchorage length (adapted from Belluco and Faleschini 2025). Results show that, adopting the proposed models significantly reduces the variability of the obtained compared that obtained with current design formulations. This happens because current code models do not properly account for the influence of the prestress release. Furthermore values turn out to be closer to the target one, ensuring a more homogeneous level of reliability than the current design models of MC20 and EC2:2023 (more details in Belluco and Faleschini 2025). 4. Conclusions In this work, the model uncertainty assessment of fib Model Code 2020 and the 2 nd gen. Eurocode 2 design formulations for the transmission and anchorage lengths was carried out. To this end, two extensive databases of experimental measures from the existing scientific literature has been collected. Results show that the prestress release method deeply affects both the transmission and anchorage lengths. In particular, the estimated transmission lengths of the fib Model Code 2020 are, on average, equal to or slightly higher than the observed experimental values; on the contrary, 2 nd generation Eurocode 2 (2023) estimated transmission lengths that are, on average, equal or slightly lower than the experimental ones. Regarding the anchorage length, it has been shown that values predicted according to fib Model Code 2020 exceed the required target level of reliability regardless of the type of prestress force release method, and they could be even reduced (particularly for the gradual release case). Instead, anchorage lengths calculated according to the 2 nd generation Eurocode 2 (2023) for the sudden release case need to be increased to guarantee the expected level of reliability, while no significant adjustments are necessary for the gradual release case. Finally, new probabilistic coefficients are proposed to adjust both codes’ formulations and ensure the achievement of suitable target reliability lengths to be adopted in design situations. References Belluco S., Faleschini F. 2025. Probabilistic calibration of design resistance models for the anchorage length of prestressing strands considering model uncertainty, Structural Safety 117 (2025) 102631. Belluco S., Faleschini F., Hofer L., Pellegrino C. 2023. Probabilistic investigation of transmission length formulations considering model uncertainties, Engineering Structures 295 (2023) 116837 EN 1992-1-1:2004. Design of concrete structures — Part 1-1: General rules and rules for buildings. Brussels (Belgium): European Committee for Standardization; 2004. EN 1992-1-1:2023. Eurocode 2: Design of concrete structures - Part 1-1: General rules – Rules for buildings, bridges and civil engineering structures. European Committee for Standardization (CEN); 2023 Faleschini F, Hofer L, Belluco S, Pellegrino C. Reliability-based design of transmission and anchorage lengths in prestressed concrete elements. Struct Concr 2023;24(3):3573–91. fib Model Code for Concrete Structures 2010. Berlin (Germany): Wilhelm Ernst & Sohn Verlag fur Architektur und Technische; 2013. fib Model Code for Concrete Structures 2020. Federation internationale du beton ( fib ); 2024. Holický M, Retief JV, Sýkora M. Assessment of model uncertainties for structural resistance. Probab Eng Mech 2016; 45:188–97 Kiureghian AD, Ditlevsen O. Aleatory or epistemic? does it matter? Struct Saf 2009; 31(2):105–12 Pourreza F, Mousazadeh M, Basim MC. An efficient method for incorporating modeling uncertainties into collapse fragility of steel structures. Struct Saf 2021;88: 102009