Refurbishment of a heritage concrete tied arch bridge across river Lys

In the past, concrete arch bridges were built to cross moderate spans, whereas today the alternative of beam bridges is preferred. In view of their aging, it has become necessary to assess carefully the load-carrying capacity of these historic bridges. In the case of the seriously damaged Pontweg bridge, after inspection in 2012, the general opinion concluded that the bridge should be demolished and replaced. Nevertheless, the arch shape, the characteristic nodes and RC-hangers make this bridge a rare heritage structure. However, careful analysis and testing allowed to convince parties involved, that restoring the load-carrying capacity and refurbishment was possible. Both numerical simulation and dynamic testing have demonstrated the necessity to reinforce substantially the lower chord and the floorbeams. Due to the necessity of rebar splices an additional reinforcing beam was connected to the lower chord. The sealing of the arches and hangers was successful, due to the use of micromortar, whereas an unfortunate polymer-containing repair product of the deck, has modified the texture and appearance of these parts. Fortunately, the arches and hangers have kept most of the concrete colour and texture and show the effort made to preserve the bridge. At present a load test is being considered. Replacing the movable bearings required temporary lifting of one side of the bridge. This demonstrates that an adequate type of repair product is important to preserve the characteristic aspect and texture of historic arch structures.In the past, concrete arch bridges were built to cross moderate spans, whereas today the alternative of beam bridges is preferred. In view of their aging, it has become necessary to assess carefully the load-carrying capacity of these historic bridges. In the case of the seriously damaged Pontweg bridge, after inspection in 2012, the general opinion concluded that the bridge should be demolished and replaced. Nevertheless, the arch shape, the characteristic nodes and RC-hangers make this bridge a rare heritage structure. However, careful analysis and testing allowed to convince parties involved, that restoring the load-carrying capacity and refurbishment was possible. Both numerical simulation and dynamic testing have demonstrated the necessity to reinforce substantially the lower chord and the floorbeams. Due to the necessity of rebar splices an additional reinforcing beam was connected to the lower chord. The sealing of the arches and hangers was successful, due to the use of micromortar, whereas an unfortunate polymer-containing repair product of the deck, has modified the texture and appearance of these parts. Fortunately, the arches and hangers have kept most of the concrete colour and texture and show the effort made to preserve the bridge. At present a load test is being considered. Replacing the movable bearings required temporary lifting of one side of the bridge. This demonstrates that an adequate type of repair product is important to preserve the characteristic aspect and texture of historic arch structures.P