PSI - Issue 78

Annalisa Franco et al. / Procedia Structural Integrity 78 (2026) 1245–1252

1248

1. Statistical analyses of experimental data (for both composite and dry fabric); 2. Individuation of the best fitting probabilistic model by using a Kolmogorov-Smirnov (K-S) test; 3. Evaluation of characteristic X k and design X d values according to the best fitting probabilistic model and calculation of partial safety factor m according to Eq. (4). 3. Database of experimental results Experimental results of tensile tests on IMC system and the relative dry fabrics, coming from the qualification procedure according to (EAD 340275-00-0104, 2020), have been collected. According to the mentioned EAD, the number of single tensile tests required for the qualification of each IMC system is 20, and the tensile strength σ u is calculated on the basis of the fabric cross-sectional area measured in accordance with the method indicated in Annex E of the EAD itself. As regards the dry fabric, a minimum of 5 specimens is used to determine the tensile strength σ f . In the current study, 17 IMC systems have been analysed, made of 4 type of fabrics (glass, basalt, steel and PBO) and two types of matrix (lime-based mortar, LM and cement-based mortar, CM). The number of tests collected per type is listed in Table 1. In all cases, the available data are statistically almost sufficient to interpret the strength of the specimens with probabilistic models. However, they are still useful to have an overview of the behaviour of various materials evidencing where to focus future in-depth analyses.

Table 1. Number of single tests carried out on IMC systems

T ESTS ON IMC SYSTEMS

T ESTS ON THE DRY FABRIC

IMC SYSTEM TYPE

N° OF SYSTEMS

GLASS + LM BASALT + LM STEEL + LM STEEL + CM

5 3 2 2 2 3

100

48 58

60 40 40 40 60

80

PBO + LM PBO + CM

46

3.1. Statistical analysis of experimental data (unconditioned specimens) The experimental results for the various specimens, in terms of tensile strength σ u of the composite system and σ f of the dry fabric, were compared with 3 theoretical probabilistic distributions: Normal, Lognormal and 3-parameter (3-p) Lognormal. In Table 2, the Probability Density Functions (PDF) and the identifying parameters associated to these distributions are summarized. In particular, the Normal and Lognormal distributions require the calculation of the parameters μ (scale parameter) and σ (shape parameter), while the 3 -p Lognormal requires also a third parameter ϑ (threshold), which defines the point where the support set of the distribution begins. Such distributions are also plotted in Figure 1 and 2, for comparison with the experimental data of σ f and σ u in terms of both PDFs and Cumulative Distribution Functions (CDFs) for the glass and basalt systems, respectively, while in Table 4 the obtained fitting parameters of each probability distribution are listed for all the examined datasets.

Table 2. Probability theoretical models

DISTRIBUTION

PDF

DISTRIBUTION PARAMETERS





2

x





1



Normal

μ, σ

( | , )  

2 e

 y f x

2





2  





2

ln

x





1



Lognormal

μ, σ

( | , )  

e

 y f x

2



2



2  

x







2

   

   

ln(

  )

x

2   

1



3-p Lognormal

μ, σ, ϑ

2

( | , , )   

e

 y f x







2   

x

 