PSI - Issue 5

Tiago Mendonça et al. / Procedia Structural Integrity 5 (2017) 48–54 Mafalda Monteiro et al./ Structural Integrity Procedia 00 (2017) 000 – 000

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The Belver Bridge was built by Empreza Industrial Portugueza and dates back to 1905. As the previous bridge, this one is also an upper platform supported on a steel continuous box-girder truss. It has 4 spans. Supports are rigged masonry piers and abutments. On the left bank the deck transposes Beira Baixa railway. The bridge of Chamusca was made by the Compagnie de Fives-Lilles and dates from 1909. It consists of a spatial steel box-girder truss with a lower platform that is divided in 111 spans and is supported over rigged masonry piers.

Fig. 2. a) Belver bridge b) Chamusca bridge, both over Tagus river.

These bridges constitute local traffic restrictions in the roadways where they are inserted. Platforms’ width is reduced and causes transversal strangulation. The crossing of oncoming vehicles is very difficult and is one of the challenges to solve in the rehabilitation.

2.2. Methodology and tasks performed for bridge rehabilitation design project

The Methodology adopted by Betar comprised several phases of study. At an early stage Detail and Topographic surveys of the structure were done and considered essential for a previous structure’s characterization and of its constraints. Tests plans were also elaborated. The next stage comprised Main Inspections (visual), Underwater Inspections, Mapping of Anomalies and Special Inspections with Materials Tests. One may highlight the following:  Concrete characterization tests (coating measurements, carbonation depth and chloride content, electric potential of the reinforcement, concrete resistivity and moisture content, compressive strength, ultrasound integrity, petrographic tests);  Tests for steel characterization (chemical composition, tensile strength, ductility, Charpy and fatigue resilience) In the subsequent stage, those results were considered in the structural assessment of each structure (Table 1). Different scenarios of intervention were considered throughout a sensitive analysis of the main resistant parameters. Each one engaged a strengthening solution that was developed at a conceptual design level and quantified. The optimal solution for each bridge that fitted the technical and economic criteria was then obtained from comparison. Finally, the elected solution was developed for detailed design. This stage included the assessment of structures’ response to the regulatory actions. The strengthening solutions and structural changes were accurately evaluated and designed adjusting them to the existing constraints. The detailed design project encompassed all the necessary specifications for its correct implementation on site and the complementary studies (eg hydraulic studies). BETAR has also accomplished technical assistance during construction stage.