PSI - Issue 64

Isabella Mazzatura et al. / Procedia Structural Integrity 64 (2024) 114–121 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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The beta, the normal, and the gamma distributions are fitted to the data histogram, such as Fig. 9a shows. All the distributions result to fit well to the data, and for simplicity the normal distribution is chosen. As further demonstration of the good fitting, the Q-Q (quantile-quantile) plot is given in Fig. 9b. Therefore, the error of the technique in locating post-tensioned ducts, is well described by a Normal distribution with parameters (expressed in cm): (0.702, 1.52) The information can be employed in a probabilistic assessment of the post-tensioned element, by modelling the uncertainty in the position of the post-tensioning steel using the above statistical distribution when evaluating the eccentricity of the prestressing. It is worth noting that, in average, the error is positive, meaning that the NDT is positioning the duct in a lower location than the actual one. When dealing with simply-supported post-tensioned beams, this results in an overestimation of the prestressing effects and, therefore, this should be considered in the value of the estimated cracking and ultimate bending moments when checking the corresponding SLS and ULS. The fact that the positive error is increasing as the height of the sample decreases, can also derive on the overestimation of the compensating effect of prestressing (which depends on the inclination of the cable) in the assessment of shear capacity in the zones critical to shear. It is also of interest to point out that the characteristic value of the error is similar to the range of the maximum tolerances in the position of post-tensioned tendons as required by some codes at the time when most of bridges with simply-supported post-tensioned beams were executed, in the range of 25 mm. Acknowledgements The last co-author thanks the support given by Grant PID2021-126405OB-C31 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” . References Beben, D., Mordak, A., & Anigacz, W. (2012). Identification of viaduct beam parameters using the Ground Penetrating Radar (GPR) technique. NDT and E International , 49 , 18 – 26. Clem, D. J., Schumacher, T., & Deshon, J. P. (2015). A consistent approach for processing and interpretation of data from concrete bridge members collected with a hand-held GPR device. Construction and Building Materials , 86 , 140 – 148. dos Santos, V. R. N., Al-Nuaimy, W., Porsani, J. L., Hirata, N. S. T., & Alzubi, H. S. (2014). Spectral analysis of ground penetrating radar signals in concrete, metallic and plastic targets. Journal of Applied Geophysics , 100 , 32 – 43. Giannopoulos, A., Macintyre, P., Rodgers, S., & Forde, M. C. (2002). GPR detection of voids in Post-Tensioned concrete bridge beams. Ninth International Conference on Ground Penetrating Radar , 376 – 381. Kohl, C., & Streicher, D. (2006). Results of reconstructed and fused NDT-data measured in the laboratory and on-site at bridges. Cement and Concrete Composites , 28 (4), 402 – 413. Liu, S., Weng, C., Jiao, P., Wang, F., Fu, L., Meng, X., & Lei, L. (2013). GPR signal analysis of post-tensioned prestressed concrete girder defects. Journal of Geophysics and Engineering , 10 (3). Pasculli, D., Natali, A., Salvatore, W., Morelli, F., & Morandi, D. (2018, August 20). Investigation of reinforced concrete bridges by using a dual polarized high-frequency GPR. 2018 17th International Conference on Ground Penetrating Radar, GPR 2018 . Pollock, D. G., Dupuis, K. J., Lacour, B., & Olsen, K. R. (2008). Detection of Voids in Prestressed Concrete Bridges using Thermal Imaging and Ground-Penetrating Radar. Washington State Transportation Center (TRAC) . Shaw, M. R., Millard, S. G., Molyneaux, T. C. K., Taylor, M. J., & Bungey, J. H. (2005). Location of steel reinforcement in concrete using ground penetrating radar and neural networks. NDT and E International , 38 (3), 203 – 212. Sławski, L., Kosno, L., & Świt, G. (2016). Evaluation of Precast Pre-post-tensioned Concrete Bridge Beams with the Use of GPR Method. Procedia Engineering , 156 , 443 – 450. Soldovieri, F., Persico, R., Utsi, E., & Utsi, V. (2006). The application of inverse scattering techniques with ground penetrating radar to the problem of rebar location in concrete. NDT and E International , 39 (7), 602 – 607. Terzioglu, T., Karthik, M. M., Hurlebaus, S., Hueste, M. B. D., Maack, S., Woestmann, J., Wiggenhauser, H., Krause, M., Miller, P. K., & Olson, L. D. (2018). Nondestructive evaluation of grout defects in internal tendons of post-tensioned girders. NDT and E International , 99 , 23 – 35. Wai-Lok Lai, W., Dérobert, X., & Annan, P. (2018). A review of Ground Penetrating Radar application in civil engineering: A 30-year journey from Locating and Testing to Imaging and Diagnosis. NDT and E International , 96 , 58 – 78.