Saw-cut method for stress-strain assessment in prestressed concrete: Experimental validation and numerical simulation

[EN] Prestressed concrete (PC) is used in a wide range of building and civil structures. As these structures approach the end of their in-service life, it is essential to assess their current stress-strain condition. In this study, the effectiveness of the Saw-Cut Test (SCT) as a non-destructive method to estimate residual prestressing forces in PC members is explored. Mechanical strain gauges varying nominal measurement base lengths (NMBLs) are employed, enabling analysis of strain relief across the generated Isolated Concrete Block (ICB). Special attention was given to key parameters such as cut spacing (S) and depth (D). Relative displacements and strain profiles were measured during progressive cutting and compared with numerical model simulations. The findings highlight a symmetric stress relief behavior of the ICB and a strong influence of cut depth in governing the decompression threshold, reached for D = [30¿ 35] mm with S = 120 mm in the unbonded post-tensioned beam tested. The use of multiple NMBLs enhanced measurement reliability. The numerical model accurately reproduces the experimental trends in displacements, with differences below ±0.004 mm. The study confirms that top-surface measurements are sufficient for effective strain change determination, while lateral instrumentation, although informative, was found non-essential. These results support the integration of SCT into broader in-situ assessment campaigns, offering a robust and scalable methodology for assessing residual performance of aging PC structures.