Highway Viaduct Renovation

SummaryThe viaduct is positioned on the highway, connecting the city of Sofia with the northern part of Bulgaria. The total length of the viaduct is 645m, where it has 16 spans of 40.5m length each. The maximum height of the piers is 50m.During the renovation of the deck and the piers has been discovered that some of the 120t post-tensioned concrete beams are in very bad condition. Approximately more than 50% from their origin load bearing capacity has been diminished. A decision was taken for these beams to be replaced by steel ones.In the paper are described the design and the implementation of the renovation of the important structural elements, including the problems which were encountered upon. The design approach of the different elements has also been analyzed. The main innovation in the project is in the usage of concrete and steel beams in one and the same span. Due to the replacement of some post-tensioned beams with steel beams, the beneficent requested a full-scale load test of the bridge to be provided before it enters in operation again. The results from the static and dynamic tests of the renovated viaduct have been provided.The renovated viaduct is in operation since the beginning of December 2015.