Issue 51

G. Ramaglia et alii, Frattura ed Integrità Strutturale, 51 (2020) 288-312; DOI: 10.3221/IGF-ESIS.51.23 302 The assessment of the statistical parameters confirms the reliability of the Stassi-D’Alia model compared to others. It is interesting to note that the model is weakly depended on the formulation - eqs. (13) versus (18) - used for the effective confining stress, , l eff f (Fig. 9). Hence, the statistical results confirmed the Stassi-D-Alia model to be the best analytical tool to assess the axial capacity of confined clay brick masonry. (a) (b) (c) Figure 9 : Statistical parameters changing the calculation approach of the effective confining stress, , l eff f : a) MAPE, b) MSE and c) R 2 . C ONCLUSIONS our confinement models were derived by the classical failure criterions available in the scientific literature. These models were used to assess the axial capacity of masonry specimens made of solid clay brick and strengthened with several types of strengthening systems (GFRP, CFRP and BFRP). They were carried out to assess the increase of the axial capacity due to the wrapping interventions. These models are fully based on mechanical parameters representative of the materials: tensile and compressive strengths of masonry and the effective confining stress. The reliability of the mechanical models was assessed by comparison with relevant experimental programs. The strength values are derived by 67 experimental test results. They allow to apply the mechanical model to the masonry specimens actually tested. The effect of confinement is strongly related to the effective confining stress. It was evaluated according to two main approaches available in the literature. Between the several mechanical models the Stassi D’Alia was proposed to assess the axial capacity of confined masonry columns. The reliability of this model was demonstrated by comparing the theoretical values with the experimental results. In order to confirm the potential of this model, the comparison was carried out considering also the other mechanical models. The comparison confirmed the Stassi-D’Alia model to be the best approach to assess the axial capacity of masonry columns made of solid clay brick and strengthened with innovative composite systems. It was remarked both by direct comparison of experimental results with the numerical previsions and by statistical parameters. In particular, the Stassi-D’Alia model provided good fitting for the entire range of the effective confining stresses. The model indicates that the axial capacity of the strengthened masonry is not much influenced by the tensile strength of masonry, despite the model is potentially able to account for such variations if more refined values are F