Empa scientists Masoud Motavalli and Elyas Ghafoori have developed a method to protect historic iron bridges from wear and tear in line with monument protection regulations. They were assisted by Alain Nussbaumer, a specialist in steel fatigue at the École polytechnique fédérale de Lausanne (EPFL).
The carbon fibre-reinforced polymer (CFRP) plasters developed by the two scientists was used for the first time in 2015 to reinforce the Münchenstein railway bridge near Basel, built in 1892. In January of this year, the method – which has since been refined and patented – was used on a similar bridge in Australia, the 122-year-old Diamond Creek Bridge near Melbourne. A network of sensors monitors the reinforcement effect of both bridges, and the data from the Australian bridge even provides load data to Empa in real time.
Unlike wood or concrete, CFRP reinforcement is considerably more complicated to affix to old steel girders. However, the Empa method affixes CFRP plates to the bridge using anchors rather than sticking the CFRP directly to the bridge. “It’s important that the carbon fibres do not break when attaching the CFRP,” Ghafoori said in a press release.
Their method is generating much interest around the world. The French institute of science and technology for transport, development and networks (IFSTTAR), the French centre for mobility (CEREMA), and delegations from China and the US have already expressed interest.
If the system gains traction, then it could make “many steel bridges from the 19th century future-proof, allowing them to significantly outlive their younger reinforced concrete counterparts”, according to Empa.
