Strengthening of a Single Track Railroad Steel Truss Bridge with Addition of a Two Lane Highway Deck

The need for a highway link was highlighted after 12 people died in a ferry accident in 2002 on the Karakaya Dam reservoir near Malatya, Turkey. The closest link to the ferry route is a thirty year old, 2030 meter long single track steel truss railroad bridge. The existing bridge, with 29 identical spans, is supported on massive piers. The existing steel truss superstructure has design-originated seismic deficiencies. This is because the current seismic requirements of the bridge specifications have increased since recent regional analysis has shown demands to increase as compared to past assessments. The main focus of this paper is to demonstrate that the additional highway deck placed on top of the truss not only provides a needed highway link but also helps the bridge structurally to mitigate the seismic deficiencies. As part of this effort, the seismic and structural reliability of the bridge, review of existing design, modifications, material tests and structural monitoring test results are evaluated. The provided solution of the upper highway deck system not only adds mass but also rigidity to the truss bridge, helping to solve some of the inherent design problems associated with the existing structural system.