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Computers and Concrete Volume 34, Number 4, October 2024 , pages 379-391 DOI: https://doi.org/10.12989/cac.2024.34.4.379 |
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Flexural performance of prestressed UHPC beams with different prestressing degrees and levels |
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Zongcai Deng, Qian Li, Rabin Tuladhar and Feng Shi
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| Abstract | ||
| The ultra-high performance concrete (UHPC) mixed with hybrid fibers has excellent mechanical properties and durability, and the hybrid fibers have a certain impact on the bearing capacity, deformation capacity, and crack propagation of beams. Many scholars have conducted a series of studies on the bending performance of prestressed UHPC beams, but there are few studies on prestressed UHPC beams mixed with hybrid fibers. In this study, five bonded post-tensioned partially prestressed UHPC beams mixed with steel fibers and macro-polyolefin fibers were poured and subjected to four-points symmetric loading bending tests. The effects of different prestressing degrees and prestressing levels on the load-deflection curves, crack propagation, failure modes and ultimate bearing capacity of beams were discussed. The results showed that flexural failure occurred in the prestressed UHPC beams with hybrid fibers, and the integrity of specimens was good. When the prestressing degree was the same, the higher the prestressing level, the better the crack resistance capacity of UHPC beams; When the prestressing level was 90%, increasing the prestressing degree was beneficial to improve the crack resistance and ultimate bearing capacity of UHPC beams. When the prestressing degree increased from 0.41 to 0.59, the cracking load and ultimate load increased by 66.0% and 41.4%, respectively, but the ductility decreased by 61.2%. Based on the plane section assumption and considering the bridging effect of short fibers, the cracking moment and ultimate bearing moment were calculated, with good agreement between the test and calculated values. | ||
| Key Words | ||
| flexural behavior; hybrid fibers; prestressing degrees; prestressing levels; UHPC beams | ||
| Address | ||
| Zongcai Deng and Qian Li: The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, 100 Pingyuan Park, Chaoyang District, Beijing 100124, China Rabin Tuladhar: College of Science & Engineering, James Cook University, 383 Flinders Street, Townsville, QLD 4814, Australia Feng Shi: Ningbo Shike New Material Technology Co. Ltd, 518 Xinmei Road, Ningbo 315000, China | ||