Laboratory tests on strengthening steel and concrete elements with high-strength concrete

<p>In the University of Architecture, Civil Engineering and Geodesy in Sofia a research project has started in 2018 aiming to investigate the possibilities of local production and application of high- strength concrete (or even UHPFRC) for strengthening existing structures in Bulgaria. Under this project laboratory tests of steel orthotropic bridge deck specimens as well as reinforced concrete beams, strengthened with high-strength concrete are performed. All elements are strengthened with an additional layer of high-strength concrete with thickness of 50mm on top.</p><p>The results obtained from the tests are summarized in this article. Comparative analysis showing the effect of this strengthening method is also presented. At the end summary and conclusions are drawn. Future steps for enhancing and promoting this strengthening technique in Bulgaria are outlined.</p>

Standardised bridge weigh-in-motion data and its applications in bridge engineering

<p>Applying actual traffic data in bridge analyses will provide more accurate results compared to the results obtained according to the Eurocode traffic load models. Bridge Weigh-in-Motion (B-WIM) measurements are an excellent tool to produce such data. Using B-WIM data as a part of the bridge design or assessment processes has a large potential, but the lack of widely adopted standardised data format hinders broader utilisation of it. This study proposes a new standardised format to present the measured B-WIM data so that in the future, developed software can directly utilise any available B-WIM data. This would make calculations with multiple different traffic compositions and types straightforward and enable the basis for further utilisation of B-WIM data in bridge design/assessment. To demonstrate the benefits, a fatigue case study of an orthotropic bridge deck was conducted, and the results were compared to ones obtained according to Eurocode FLM 4.</p>

Replacement of the cable-stayed bridges over the river Rhine in Leverkusen and Duisburg

This paper deals with the replacement of existing highway bridges by the example of two bridges over the river Rhine in Duisburg-Neuenkamp and in Leverkusen. Both mainly welded cable stayed bridges are under traffic since circa 1970 - 1965 and are constructed as welded steel girder bridges with an orthotropic bridge deck. Recent damages ito the steel structure of the bridge deck reduced the service lives of both bridges significantly, therefore, the bridges needed to be replaced within a short time, while maintaining the traffic during all construction stages. The replacement strategies, traffic changes during construction and the design requirements are described in the following. Both existing bridges in Leverkusen and Duisburg-Neuenkamp are under traffic since built in 1965 respectively 1970 (Figure 2). They are cable-stayed bridges and constructed as steel girders with orthotropic bridge decks. Most parts of the bridges are welded. The bridge over the Rhine near Duisburg­Neuenkamp is one of the first completely welded bridges in Germany. Currently more than 100’000 vehicles per day pass the bridges, with a portion of more than 10 % heavy lorries. Due to the increasing traffic, in connection with some inadequate fatigue design, details a steady increase of damages in steel bridges is noted on many steel bridges such as in Duisburg-Neuenkamp and in Leverkusen. The construction of the new bridge is planeed with a temporary lateral off-set of about 14.40 m. After that, the existing bridge can be dismantled. Then the northern bridge is to be built in its final position and finally, the southern bridge has to be launched in transverse direction into its final position (Figure 3) and the connections to the road network is finalized. The Leverkusen bridge with a main span of 280 meters is also a 2 deck solution, where the northern bridge is built first in its final position, than after dismantling of the existing bridge, the southern bridge can be built in its final position.