PSI - Issue 84

Alessandro Lipari et al. / Procedia Structural Integrity 84 (2026) 1087–1094

1089

Fig. 1. DIC-processed cracking patterns of S60O1Auc: (a) side view, (b) bottom view; and S60N1Auc: (c) side view, (d) bottom view.

Table 1. Analyzed experiments. Test Skew angle [°]

Age [days]

f cm,cube [MPa] 69.4 65.1* 72.3**

f tm,split [MPa]

ρ l [%]

ρ t [%]

P max [kN]

S60O1Auc S60N1Auc S45N1Auc S75N1Auc

30 30 45 15

123 152 259

- - -

0.948 0.258 580.1 0.948 0.258 606.4 0.948 0.258 420.8

302 70.47*** 3.75 0.948 0.258 745.9 * The average cube compressive strength for specimen S60N1 was obtained 1 day after the first test. ** The average cube compressive strength for specimen S45N1 was obtained 28 days after the first test due to public holidays. *** The average cube compressive strength for specimen S75N1 was obtained 7 days after the first test. 3. Linear finite element analysis To determine the acting shear forces, a linear finite element analysis is carried out by using the software SCIA Engineer 25 (Nemetschek SCIA, 2025). SCIA uses the Mindlin-Reissner theory for plate analysis. The slab is modeled as a plate on a line roller and line pin support using elements of 0.05 m in size. The model is based on a simplified assumption of concrete class C25/30, thus E = 31.5 GPa, and v = 0.2. The load combination used for generating the results is the self-weight and the applied failure load (as a single concentrated load), with load factors set to 1 to replicate the test conditions. Fig. 2 shows the results for the shear force v x for S60N1Auc. 4. Eurocode 2 The recently revised Eurocode 2, part 1-1 (European Committee for Standardization, 2023), hereinafter EC2, has endorsed the Critical Shear Crack Theory (CSCT) (Muttoni & Fernández Ruiz, 2008) for the shear resistance of concrete members without shear reinforcement, which is now given in terms of shear stresses (Muttoni et al., 2023). Two formulations are given, both referred to as “detailed verification”: one in Section 8 (Ultimate Limit States), mainly thought for design, and the other in the informative Annex I (Assessment of Existing Structures). The former is derived from the latter (Muttoni et al., 2023) and will be dealt with in this paper. In fact, the strain-based verification in Annex I, in spite of its increased complexity, does not necessarily return greater shear strengths (Lipari, 2025).