Jang-Ho Jay Kim, Hyeon-Chan Park, Jin-Su Kim, Woo-Ri Kwon
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引用次数: 0
Abstract
Prestressed concrete (PSC) is a structural system in which compressive forces are intentionally applied through high-strength tendons to counteract tensile stresses and prevent cracking. Although PSC has been widely adopted in large-scale constructions such as bridges, buildings, and tanks due to its long service life, the accurate long-term prediction of prestress (PS) losses remains a critical issue, as time-dependent reductions in prestressing force—caused by concrete creep, drying shrinkage, anchorage slip, and steel relaxation—can compromise structural integrity and durability. Despite its importance, most previous studies have relied on short-term laboratory tests or numerical simulations, and long-term field data—especially for ultra-high-strength tendons—remain extremely limited. In this study, PS losses were monitored continuously over approximately 10 years in post-tensioned PSC beams embedded with steel tendons of three different tensile strengths: 1860 MPa, 2160 MPa, and 2400 MPa. The measured strain data were compared against prediction equations provided in major design codes to assess their applicability to modern high-strength tendons. The experimental results demonstrated that tendons with higher tensile strengths (2160 MPa and 2400 MPa) exhibited distinct long-term PS loss characteristics, including smaller loss rates and different seasonal and spatial variation patterns, compared to lower-strength tendons. The existing code-based prediction equations, originally developed for 1860 MPa tendons, significantly underestimated the long-term losses in high-strength tendons, highlighting the need for model refinement. Based on the long-term measurements, the study proposes modified PS loss prediction equations that better reflect the time-dependent behavior of ultra-high-strength tendons. These findings not only offer rare empirical data for validation but also provide critical insight for improving code-based PS loss predictions, with the potential to influence future revisions of design provisions for PSC structures.
期刊介绍:
Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.