PSI - Issue 62

Alberto Gennari Santori et al. / Procedia Structural Integrity 62 (2024) 339–346 Gennari Santori A. et al. / Structural Integrity Procedia 00 (2019) 000–000

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of all these aspects, in fact a detailed investigation campaign that gave several important information about the structural behavior of the viaduct and about its characteristic mid-span joints. In order to obtain these results different technologies and methodologies have been applied with good results obtained. From an accurate analysis of the experimental data recorded the main findings are the following: • In correspondence of the special joints located on span No. 7 higher vertical displacements have been recorded. During the special inspection was noted that the lower bearings were detached, therefore a static load testing was performed to evaluate in detail its mechanical behavior. Results have shown an elastic response in the range of the applied loads. • During the transit of an exceptional vehicle characterized by a load equal to 150 tons the vertical displacements of all the special joints have been monitored. Furthermore, the axial stress increment of Dywidag bars in correspondence of special joints (spans 5, 7 and 9) has been evaluated. Results have shown a similar behavior between the analyzed structural elements. • The axial stress on the Dywidag bars was evaluated using two different techniques: the first using a dynamic approach while the second with the X-Ray diffraction (XRD). Results have shown higher values if compared with the designing ones probably correlated to the values of the relative vertical displacements measured on the special joints. • The on-site tests carried out during the transit of an exceptional vehicle and during the execution of a static load test carried out on the span No. 7 highlighted axial stress values lower than the yielding one. Furthermore, the axial load increment acting on the Dywidag bars produced by live load could lead to fatigue problems. This aspect was not the topic of the paper; however, it is an important factor and with the other findings highlighted by the experimental investigation described on the article led to the conclusion that the special joints need to be strengthened.

Acknowledgments

The authors are grateful to Giulio Ventura, Mauro Corrado and Oscar Borla from the Department of Structural, Geotechnical and Building Engineering of Politecnico di Torino for sharing their XRD test results on Dywidag bars. A special thanks to all the members of the Structural Diagnostic Laboratory of the “Centro di Ricerca e Sperimentazione Stradale di Cesano” Anas S.p.A.

References

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