PSI - Issue 84

Michele D’Amato et al. / Procedia Structural Integrity 84 (2026) 1175–1182

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Fig. 2. Bridges distribution for (a) design year; (b) beams construction material.

3. Database Analysis In the following section, a summary of data analysis results is presented based on the information archived in the SAFOTEB database. In particular, the strengths of reinforcing steel bars, concrete, and prestressing steel are analyzed and discussed. All percentages are calculated based on the number of data points available for each specific material sub-sample. It should be noted, however, that for many of the bridges analyzed, some data sets were incomplete. A comprehensive analysis of the data from the entire database is reported in (D’Amato et al., 2025). 3.1. Reinforcing steel A sample of 374 records concerning the reinforcing steel class of all structural elements is examined, primarily derived from design nominal values (90% – 338 records) and, to a lesser extent, from acceptance certificates (3% – 13 records) and in situ tests (6% – 23 records). With reference to each structural element examined, a clear prevalence of the FeB44 steel class (yield strength f y = 440 MPa) was recorded for beams (Fig. 3a), piers, abutments, foundations, and slabs, with the exception of cross beams, where ALE (high-strength steel; f y = 430 MPa) predominates. Further analysis of the data from each source across all structural elements reveals that FeB44 is the most frequent class, accounting for 17% of design nominal values, 100% of acceptance certificates, and 52% of in situ tests. Furthermore, an analysis of the average yielding strength and Coefficient of Variation (CV) is performed on data from each structural element, referring to both acceptance certificates and in situ tests. Specifically, acceptance certificates only provide data for FeB44 steel, showing a mean yield strength of 508 MPa with a 7% CV. Conversely, in situ testing covers a broader range of classes, including FeB44, ALE, Aq. 60, and Aq. 50-60, with the highest dispersion observed in ALE steel (CV=7%). 3.2. Concrete A sample of 282 records concerning the concrete class of all structural elements is obtained from design nominal values (92% – 259 records), acceptance certificates (3% – 8 records) and in situ tests (5% – 15 records). With reference to each structural element examined, the most common concrete classes are R400 (compressive strength of R ck = 40 MPa) for beams (Fig. 3b), R300 (compressive strength of R ck = 30 MPa) for cross-beams, piers, and slabs and finally R250 (compressive strength of R ck = 25 MPa) for abutment and foundation. Further analysis of the data from each source across all structural elements reveals that R300 is the most frequent class, accounting for 28% of design nominal values, and R400 for acceptance certificates (50%), in situ tests (67%). Furthermore, an analysis of the average compressive strength and the CV was conducted for each structural element, based on data from acceptance certificates and in situ tests. In this study, cylindrical compressive strength was utilized. The results indicate that the average strengths are consistent with nominal values and show low dispersion. Specifically, the CV remained below 12% for acceptance certificates and under 29% for in situ tests.