Issue 40

Z.S. Metaxa et al, Frattura ed Integrità Strutturale, 40 (2017) 61-73; DOI: 10.3221/IGF-ESIS.40.06 72 • For the case of incremental increasing loading-unloading loops, the FOBGs seems to be the more mature technology for strain sensing of cementitious material for low straining regime. For large displacements/strains damage on the brittle fiber might occur that might terminate the measurements of the sensor. The embedded coated and annealed PVA-CNT fiber gave the best sensing response in the incremental loading – unloading loops, especially at the high loading regime. Linearity between applied strain and ERC measurements was noticed for the low applied loadings while hysteresis loops were formed after every unloading branch. • Coated and annealed PVA-CNT fiber also gave satisfactory results when surface attached at the bottom surface of the prismatic specimens, showing that annealing plays a significant role on the sensing ability of the fiber, despite lower the screening ability of the fiber itself. A CKNOWLEDGEMENTS r. Alexopoulos acknowledges the financial support of the European Union (European Social Fund - ESF) and Greek National funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: “Thales - National Technical University of Athens - Development and assessment of innovative experimental techniques for the study of the mechanical behaviour of natural building stones: Applications to the conservation and restoration of monuments of Cultural Heritage” (MIS 380147). R EFERENCES [1] Kourkoulis, S.K., Prassianakis, I., Agioutantis, Z., Exadaktylos, G.E., Reliability assessment of the NDT results for the internal damage of marble specimens, International Journal of Material and Product Technology, 26 (2006) 35-56. [2] Kourkoulis, S.K., Ganniari-Papageorgiou, E., Bending of fragmented architraves restored with bolted titanium bars: A numerical analysis, Engineering Transactions, 56 (2008) 95-135. [3] Kourkoulis, S.K., Ganniari-Papageorgiou, E., Mentzini, M., Dionysos marble under bending: Α contribution towards understanding the fracture of the Parthenon architraves, Engineering Geology, 115 (2010) 246-256. [4] Kourkoulis, S.K., Mentzini, M., Ganniari-Papageorgiou, E., Restored marble epistyles under bending: a combined experimental and numerical study, International Journal of Architectural Heritage, 7 (2013) 89-115. [5] Kourkoulis, S.K, Ganniari-Papageorgiou, E., Restoring fragmented marble epistyles: some critical points, Journal of Cultural Heritage, 11 (2010) 420-429. [6] Kourkoulis, S.K., Pasiou, E.D., Triantis, D., Stavrakas, I., Hloupis, G., Innovative experimental techniques in the service of restoration of stone monuments - Part I: The experimental set up, Procedia Engineering, 109 (2015) 268- 275. [7] Triantis, D., Stavrakas, I., Pasiou, E.D., Hloupis, G., Kourkoulis, S.K., Innovative experimental techniques in the service of restoration of stone monuments - Part II: Marble epistyles under shear, Procedia Engineering, 109 (2015) 276-284. [8] Hofer, B., Fibre optic damage detection in composite structures, Composites, 18 (1987) 309-316. [9] Waite, S.R., Tatam, R.P., Jackson, A., Use of optical fibre for damage and strain detection in composite materials, Composites, 19 (1988) 435-442. [10] Takeda, S., Okabe, Y., Takeda, N., Delamination detection in CFRP laminates with embedded small-diameter fiber Bragg grating sensors, Composites Part A 33 (2002) 971-980. [11] Park, J.M., Lee, S.I., Kwon, O.Y., Choi, H.S., Lee, J.H., Delamination detection in CFRP laminates with embedded small-diameter fiber Bragg grating sensors, Composites Part A 34 (2003) 203-216. [12] Leng, J., Asundi, A., Structural health monitoring of smart composite materials by using EFPI and FBG sensors, Sensors and Actuators A: Physical, 103 (2003) 330-340. [13] Ohtsu, M., Recommendations of RILEM Technical Committee 212-ACD: acoustic emission and related NDE techniques for crack detection and damage evaluation in concrete: 3. Test method for classification of active cracks in concrete structures by acoustic emission. Materials and Structures, 43 (2010) 1187-1189. D