PSI - Issue 44

Annalisa Napoli et al. / Procedia Structural Integrity 44 (2023) 2182–2189 Annalisa Napoli, Roberto Realfonzo / Structural Integrity Procedia 00 (2022) 000–000

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It is worth highlighting that, in the comparison of Figure 2, the formulations recommended by the mentioned guidelines are applied to the considered datasets without introducing both the safety factors to use for design purposes and the limitations for the ultimate tensile failure of the fiber mesh  , . From the bar charts in Figures 2a,c,e it is noted that the new proposals provide the best predictions, followed by the models suggested by DT 215 (2018) and by ACI 549.6R_1; the less accurate estimates are provided by the formulation labelled ACI 549.6R_2, with errors up to 81% in the case of NM; however, it is common to all the guidelines’ formulas that the less accurate predictions are obtained in the case of NM, probably due to the lack of experimental data available at the time of their validation which, instead, will have been mostly based on AM (clay bricks). Finally, in Figures 2b,d,f the theoretical values, ̅   , calculated for the three groups of datasets according to Proposal 1 , Proposal 3 and the model by DT 215 (2018) , are plotted with respect to the experimental ones, ̅   . The bisector corresponds to perfect agreement between predictions and tests; therefore, points falling in the lower part of the graph indicate conservative predictions whereas points falling over the line represent unconservative situations. In the case of NM (Fig. 2f), the model by DT 215 (2018) often overestimates the experimental data (unconservative predictions), while the two proposals provide predictions better distributed about the bisector line. This consideration is again confirmed for the case of CB masonry (Fig. 2d). Finally, a larger scatter of data is observed when a unique formula is used for both NM and AM, with a greater number of data falling in the unconservative area (Fig.2a). 4. Conclusions New analytical proposals for the compressive strength of the FRCM confined masonry were derived by using a large experimental database compiled from the literature. The models were found by applying an error minimization technique to the experimental datasets which were considered either all together or grouped per masonry type (natural or artificial). The suitability of the new models was successfully verified through a comparison with the formulas reported in some international guidelines; on average, indeed, the errors on the strength predictions are about 11-13% against 20% and 20-80% obtained from the models provided by DT 215 (2018) and ACI 549.6R (2020), respectively. Acknowledgements The financial support by ReLUIS (Network of the Italian University Laboratories for Seismic Engineering - Italian Department of Civil Protection) is gratefully acknowledged (Executive Project 2022-24 - WP14). References Aiello, M.A., Cascardi, A., Ombres, L., Verre, S., 2020. Confinement of Masonry Columns with the FRCM-System: Theoretical and Experimental Investigation. Infrastructures 5(101). Alecci, V., De Stefano, M., Galassi, S., Magos, R., Stipo, G., 2021. Confinement of Masonry Columns with Natural Lime-Based Mortar Composite: An Experimental Investigation. Sustainability 13, 13742. American Concrete Institute (ACI), 2017. Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures . ACI 440.2R-17, Farmington Hills, MI: ACI. American Concrete Institute (ACI), 2020. Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix (FRCM) and Steel-Reinforced Grout (SRG) Systems for Repair and Strengthening Masonry Structures . ACI 549.6R 2020, Farmington Hills, MI: ACI. Carloni, C., Mazzotti, C., Savoia, M., Subramaniam, K.V., 2015. Confinement of Masonry Columns with PBO FRCM Composites. Key Engineering Materials 624, 644-651. CEN, European Committee for Standardization, 2002. EN 1990:2002. Eurocode 0: Basis of structural design. Napoli, A., Realfonzo, R., 2021. FRP confined masonry under compression: database collection and design proposals. Composite Structures 276, 1-24: 114490. Napoli, A., Realfonzo, R., 2022. Compressive Behavior of Masonry Columns Confined with FRCM Systems: Research Overview and Analytical Proposals. Journal of Composites for Construction 26(3): 04022019. National Research Council (CNR), 2013. Guide for the design and construction of externally bonded FRP systems for strengthening existing structures. CNR-DT200 R1, Rome. National Research Council (CNR), 2018. Guide for the design and construction of externally bonded fibre reinforced inorganic matrix systems for strengthening existing structures . CNR-DT 215/2018. Rome, Italy, CNR, (version: June, 2020). Sneed, L.H., Baietti, G., Fraioli, G., Carloni, C., 2019. Compressive Behavior of Brick Masonry Columns Confined with Steel-Reinforced Grout Jackets. Journal of Composites for Construction, 23(5): 04019037.