Examining the performance of an existing bridge requires information on several aspects, such as design choices, material properties, and ongoing degradation processes. It often happens that some critical information is not available. The traditional approach in structural engineering is to take the most conservative assumption for each unknown, following new-design principles. It will often be concluded that structural safety is not ensured and that the bridge must be strengthened or replaced. This conclusion has important economic costs, impacts on users, and environmental burden associated. In this paper, a global data-informed framework is proposed to examine structural safety of existing bridges accurately. Multiple state-of-the-art methodologies are unified to provide a comprehensive framework for bridge examination. Observations, which can include visual inspection, non-destructive testing, and structural sensing, enable the development of more realistic models of structural behaviour. A case study of a reinforced-concrete bridge in Switzerland illustrates the potential of the novel framework. Although almost no information was initially available on the bridge, the monitoring results show that it can be rationally concluded that the bridge is safe. This framework supports engineers in examining existing structures when crucial information is missing based on observations and engineering judgment.

BautechnikVolume 99, Issue 1 JahresinhaltsverzeichnisFree Access Jahresinhaltsverzeichnis Bautechnik 2021 First published: 07 January 2022 https://doi.org/10.1002/bate.202270106AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume99, Issue1January 2022 RelatedInformation

The fatigue safety of a railway bridge in riveted steel construction with a fitted ballasted trough, which has been in operation since 1897, was verified by means of monitoring. The fatigue stress of 52,060 trains was recorded during 414 measuring days. The largest measured stress values of 33 MPa occurred in the relevant tension chord in the center of the 20 m span main truss girder and were generated by the locomotives. The stress ranges decisive for the fatigue verification were thus significantly smaller than the fatigue strength of the rivet details. The fatigue safety was thus already verified at the fatigue endurance limit on the basis of the data from monitoring. The riveted steel structure is thus not critical with regard to fatigue and will be upgraded in view of a long future service duration. The measurements also show the expected large differences between the measured stress values and those calculated by means of a recalculation.

Die Ermüdungssicherheit einer Bahnbrücke in genieteter Stahlbauweise mit aufgesetztem Schottertrog, die seit 1897 in Betrieb ist, wurde anhand eines Monitorings nachgewiesen. Es wurde die Ermüdungsbeanspruchung durch 52.060 Züge während 414 Messtagen aufgenommen. Die größten gemessenen Spannungswerte von 33 MPa traten im maßgebenden Zuggurt in Feldmitte des Fachwerkträgers einer Spannweite von 20 m auf und wurden durch die Lokomotiven erzeugt. Die für den Ermüdungsnachweis maßgebenden Spannungsdifferenzen waren damit deutlich kleiner als die Dauerfestigkeit des Nietdetails. Die Ermüdungssicherheit wurde somit aufgrund des Monitorings bereits auf der Stufe der Dauerfestigkeit nachgewiesen. Die Nietkonstruktion ist folglich betreffend Ermüdung nicht kritisch und wird im Hinblick auf eine lange künftige Nutzungsdauer ertüchtigt. Die Messungen zeigen außerdem die erwarteten großen Unterschiede zwischen gemessenen und anhand einer Nachrechnung berechneten Spannungsgrößen.

Ultra-High-Performance Fibre Reinforced Cementitious Composite (UHPFRC) provides solutions to enhance existing structures and design innovative new structures. Structural UHPFRC offers 3–5 times higher compressive and tensile strengths than ordinary concrete. Due to its strain-hardening behavior and dense matrix, structures made of UHPFRC remain crack-free and waterproof, guaranteeing durability. UHPFRC has been used particularly in Switzerland with more than 280 applications since 2003. A review of UHPFRC applications in the country is proposed in this paper. Ten bridge case studies are presented, including five strengthening of existing structures and five new designs. These structures were chosen to assess the multiple benefits that UHPFRC provides compared to traditional reinforced-concrete structures. Besides structural efficiency, several construction criteria are considered, such as construction costs, material durability, environmental impacts, and construction time. Structural rehabilitation made with UHPFRC leads to cost-effective interventions, and this material also helps to preserve heritage structures. Due to its specific mechanical properties, UHPFRC enables new structures with distinctive aesthetic designs with reduced construction time. The crucial contribution of research to the first case studies is also highlighted. This link between Swiss universities and the construction industry has quickly transitioned UHPFRC Technology from academic studies to real-world applications. Nowadays, the UHPFRC Technology is maturing and applications are common in the country.

This case study describes a new approach for bridge deck replacement combining the benefits of partial-depth precast reinforced concrete (RC)panels and cast-in-place cast Ultra-High Performance Fiber Reinforced Cement-based Composite (UHPFRC) to form the top layer and to fill the joints. The partial-depth precast deck panels (about 14cm (5½ ’’) thick) include the lower rebars and are connected to the steel or concrete girder by shear studs and cast-in-place UHPFRC joint filling. The layer of UHPFRC with a thickness of about 40 mm (1½’’) includes high amount of slender steel fibers (> 3.25% in volume) and the top rebars. Rigidbond between UHPFRC and precast RC panels is obtained by appropriate surface preparation of the concrete substrate. Due to the excellent durability of UHPFRC, the cover of the top rebars in the UHPFRC layer is reduced to 15 –25 mm (5/8’’ to 1’’) which contributes in minimizing the dead load. In the US, the UHPFRC surface usually serves as riding surface (correction grinding and longitudinal grooving may be required), while in Europe and Asia asphalt pavement with a thickness of at least 40 mm (1½’’) is placed on top of the UHPFRC. Installation of the partial depth precast RC panels is very quick. Cast-in-place casting of the UHPFRC joint filling and the top layer to achieve a fully composite deck usually takes only two casting days. No formwork is required. Due to the accelerated hardening of the UHPFRC, the bridge can be opened for traffic after 1-3 days of curing time(temperatures >60°F assumed). The presented approach is intended to be used to rebuild a bridge in Switzerland in autumn 2019. The case study of the 26 m long (≈85 ft) and 7 m wide (≈23 ft) bridge demonstrates the benefits of the system.