PSI - Issue 84

Giulia Rossini et al. / Procedia Structural Integrity 84 (2026) 1183–1190

1185

All the bridges investigated are simply supported girder bridges. The tests are carried out on the girder web at midspan, chosen for two main reasons: (i) performing the cuts in this region minimizes the test invasiveness, as the concrete in the web at midspan is relatively lightly stressed; (ii) in this location the principal stresses are mainly horizontal, and therefore aligned with the orientation of the SGs, ensuring consistency between the stress field and the measurement direction. To enhance the robustness of the experimental program, multiple tests were performed on each bridge, in some cases on the same girder at slightly different locations, to reduce the influence of anomalous measurements and assess repeatability (see Figure 1 and Table 2).

Figure 1: example of in situ test, 3 tests on the same girder.

3. Bridge description and FE model 3.1. Bridges properties

The main properties of the investigated bridges are summarized in Table 1, including geometric properties, material strength and prestressing technology. For all bridges, the mean concrete compressive strength was obtained from in-situ tests (rebound hammer and/or cores), while the elastic modulus was estimated according to code provisions (UNI EN 1992-1-1, 2024) In Table 1, pre refers to pre-tensioned strands, while post indicates post-tensioned tendons. The number of saw-cut tests performed on each bridge is also reported (#tests). As a representative example, Bridge 2 is described in detail in §1.1.1, while similar considerations apply to the other bridges.

Table 1: bridge properties

Bridge n°

Construction year

prestressing technology

tendons type

span n°

span length [m]

flexural cracks

fcm [MPa]

# girder

girder spacing [m]

shear cracks

bridge type

# tests

1 2 3 1 3 1 1

13,6 26,4 15,5

5 8

2,53 1,44 2,44 1,37 3,00 0,69 0,90

yes yes yes yes

2 3 3 5 4 3 3

1 2 3 4 5 6

1990 1973 1970 1975 1975 2015

44

girder bridge

pre pre

3/8''

no no

57,8 girder bridge

5/16''

10 12

pre: 5/16'' post: Ø7

53,0 girder bridge pre + post

24

yes

girder bridge (box girders)

48,5

post

Ø7

33,5

3

no no no

no no no

40,6 girder bridge 56,1 girder bridge

pre pre

6/10'' 6/10''

16 16

24

4