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Structural Health Monitoring of Bridges

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Front. Built Environ. | doi: 10.3389/fbuil.2019.00026

Getting More Out of Existing Structures: Steel Bridge Strengthening via UHPFRC

 Henar Martin-Sanz1*, Konstantinos Tatsis1, Domagoj Damjanovic2, Irina Stipanovic3,  Aljosa sanja3,  Ivan Duvnjak2,  Eugen Brühwiler4 and  Eleni N. Chatzi1
  • 1ETH Zürich, Switzerland
  • 2University of Zagreb, Croatia
  • 3Slovenian National Building and Civil Engineering Institute, Slovenia
  • 4École Polytechnique Fédérale de Lausanne, Switzerland

Ultra High Performance Fiber Reinforced Cement-based Composite (UHPFRC) has been increasingly adopted for rehabilitation projects over the past two decades, proving itself as a reliable, cost efficient and sustainable alternative against conventional methods. High compressive strength, low permeability and high ductility are some of the characteristics that render UHPFRC an excellent material for repairing existing aged infrastructure. UHPFRC is most commonly applied as a surface layer for strengthening and rehabilitation of concrete structures, such as bridge decks or building slabs. However, hitherto its implementation with steel structures has so far been limited. In this work, the UHPFRC strengthening of a steel bridge is investigated both in simulation as well as in the laboratory, by exploiting a real-world case study: the Buna Bridge. This Croatian riveted steel bridge, constructed in 1893, repaired in 1953, and decommissioned since 2010, was removed from its original location and transported to laboratory facilities for testing prior to and after rehabilitation via addition of UHPFRC slab. The testing campaign includes static and dynamic experiments featuring state-of-the-art monitoring systems such as embedded fiber optics, acoustic emission sensors and digital image correlation. The information obtained prior to rehabilitation serves for characterization of the actual condition of the structure and allows the design of the rehabilitation solution. The UHPFRC slab thickness was optimized to deliver optimal fatigue and ultimate capacity improvement at reasonable cost. Once the design was implemented, a second round of experiments was conducted in order to confirm the validity of the solution, with particular attention allocated on the interface between the steel substrate and the UHPFRC overlay, as the connection between both materials may result on a weak contact point. A detailed fatigue analysis, based on updated FEM models prior to and after strengthening, combined with the results of a reliability analysis prove the benefits of adoption of such a solution via the significant extension of the structural lifespan.

Keywords: UHPFRC, strengthening, System Identication, Performance indicator, Fatigue, Reliabiiity assesment, Modal analyis

Received: 17 Dec 2018; Accepted: 18 Feb 2019.

Edited by:

Branko Glisic, Princeton University, United States

Reviewed by:

Pavel Ryjáček, Faculty of Civil Engineering, Czech Technical University, Czechia
Mohammad Alhassan, Jordan University of Science and Technology, Jordan  

Copyright: © 2019 Martin-Sanz, Tatsis, Damjanovic, Stipanovic, sanja, Duvnjak, Brühwiler and Chatzi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mrs. Henar Martin-Sanz, ETH Zürich, Zurich, 8092, Zürich, Switzerland, martin-sanz@ibk.baug.ethz.ch