Ultra High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC) is increasingly popular for new structural designs thanks to its high resistance both in tension and compression. When UHPFRC is complemented with steel reinforcing bars or prestressing tendons, the structure remains waterproof and crack-free under service conditions, significantly improving the durability compared to conventional reinforced-concrete designs. The Aiguillon Bridge is one of the first railway bridges entirely made of UHPFRC. Built in 2021 in Switzerland, this bridge has a single span of 6.6 m and a width of 5.4 m. The bridge is designed for a narrow track and 2 walkways. Two prefabricated elements in UHPFRC have been assembled on-site by a longitudinal cast-in-place UHPFRC keying joint. This paper presents the full-scale laboratory experiment to validate the keying joint suitability for railway bridges. This experimental investigation involves a static test on a transverse beam composed of two precast elements and the keying joint. Results show that the structure presents a post-peak ductile behavior as well as an elastic behavior under service loads. Digital-Image-Correlation measurements provide details on the cracking patterns of the interface between the keying joint and the precast elements. As the maximum resistance obtained during the experiment is in agreement with the analytical-model predictions, the concept of the keying joint is validated.
A hard challenge associated with infrastructure monitoring is to extract useful information from large amounts of measurement data in order to detect changes in structures. This paper presents a hybrid model-free approach that combines two model-free methods -Moving Principal Component Analysis (MPCA) and Robust Regression Analysis (RRA) -to detect damage during continuous monitoring of structures. While a merit of MPCA is the ability to detect small amount of damage, an advantage of RRA is fast damage detection. The objective of this paper is to exploit these two complementary advantages through an appropriate combination. The applicability of this hybrid approach is studied on a railway truss bridge in Zangenberg (Germany). Its performance is compared with that of individual methods in terms of damage detectability and time to detection. Results show that the hybrid approach has higher damage detectability and identifies damage faster than individual applications of MPCA and RRA.
<p>This paper presents the design and construction of the Aiguillon railway bridge in Switzerland, one of the first railway bridges completely made of Ultra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC). The length and width of the trough girder are respectively 6.6 m and 5.7 m. It is designed for a narrow-gauge track and two walkways. The trough is composed of two prefabricated elements in UHPFRC with steel reinforcement bars. These elements are first built in the plant and then are assembled on site by a longitudinal cast-in-place joint.</p><p>The challenges and the experiences in this project are discussed and analysed in view of future projects. Furthermore, the full-scale suitability tests to validate the joint between the two prefabricated elements are described. The test results of the structural resistance of the joints are in good agreement with analytical results.</p>
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