Fatigue of riveted and bolted joints made of puddle iron—An experimental approach

• A fatigue experimental program on puddle iron from an old bridge is carried out.
• Strain-life and fatigue crack propagation data obtained for the material
• Governing fatigue strength properties and high fatigue crack propagation rates
• Riveted and bolted joints with distinct preloads fatigue tested
• Variable amplitude S–N data of riveted joints showed consistency of Miner's rule.

In Europe and North America there are a significant number of old riveted bridges still in operation, mainly due to economic reasons. Since these structures have been exposed to increasing traffic intensity, along their long operational lives, their damage levels need to be accurately assessed in order to decide about possible repairs. Fatigue failures are a concern for these riveted steel bridges since most of them were not originally designed taking into account fatigue. Also, there is a lack of comprehensive methodologies for the fatigue assessment of riveted bridges motivated by the limited knowledge on fatigue behavior of this type of construction as well as by a deficient understanding on fatigue behavior of the old materials (wrought-iron, puddle iron or old steels) and riveted connections. This paper presents an experimental study concerning the fatigue characterization of a puddle iron from the centenary Portuguese Fão bridge. Also, the fatigue behaviors of a type of riveted and bolted joints, made of the same puddle iron, are investigated. The effect of the clamping stress on bolted joints is investigated. Besides constant amplitude loading, variable amplitude fatigue loading is also investigated for the riveted joints in order to allow the critical assessment of the linear damage summation rule.