Mode I Fatigue Crack Growth Tests on Puddle Iron Strengthened with CFRP Plates

One important subject related to structural integrity studies of bridges is to assess the fatigue behaviour of its materials and structural components. A fatigue crack initiates in zones where there is a concentration of stresses and then it may propagate at an increasing growth rate leading to structural failure. Normally, a rehabilitation campaign is associated with lower costs and time when compared to the replacement by a new bridge. The application of externally-bonded fibre reinforced polymer (FRP) plates has been used in the repair and strengthening operations of steel structures with fatigue damages. Within this subject, an experimental program was carried out to assess the fatigue crack growth (FCG) rates of old metallic materials from a centenary bridge strengthened with FRP composites. FCG tests were performed under pure-mode I loading conditions. This investigation allowed to determine the a-N curve as well as to assess the fatigue crack growth rates of reinforced and non-reinforced old metallic materials.