Evaluation of post-tensioned reinforced and fiber reinforced concrete beams by using DOFS

Artikel i vetenskaplig tidskrift, 2025

Prestressed concrete provides several advantages over traditional reinforced concrete; however, some markets remain skeptical about the use of post-tensioned structures. A crucial factor in these structures is assessing and quantifying the final force introduced into the element. This study evaluates the application of distributed optical fiber sensors (DOFS) to monitor the response of beams during tendon force introduction, long-term behavior, and loading to failure. An experimental campaign was conducted involving four beams: two standard and two post-tensioned. Additionally, the study compares the effectiveness of steel fiber reinforced concrete to determine its potential for further optimizing beam design. Key aspects analyzed include tendon force and corresponding instantaneous and deferred losses, load-deformation behavior, initial crack formation, and subsequent crack development. The results demonstrated that using DOFS in a straightforward manner allows for detailed beam response analysis across different phases. Simple hypotheses and limited sensors can accurately evaluate all tendon losses. Furthermore, fiber optics can detect potential crack candidates even in the compression stage, due to strain concentrations that lead to cracking during the loading phase.