Estrategias innovadoras de refuerzo a fatiga de conexiones en puentes metálicos mediante laminados de prfc

Abstract

Riveted metallic railway bridges are subject to a large number of cyclic loads during their service life, so they could experience fatigue problems in certain construction details, such as the stringer-floor beam connections. As an alternative to traditional strengthening solutions with bolted or welded steel plates, adhesively-bonded carbon fiber reinforced polymer (CFRP) laminates may result in a promising technique to reduce the stress level in these details. However, finding an effective strengthening solution for these cases is a considerable challenge owing to the lack of space for the intervention, the presence of rivets and the complexity of the geometry. In this sense, the lack of strengthening strategies using adhesively-bonded CFRP for the stringer-floor beam connections motivated the development of this PhD thesis. First, from experimental tests on CFRP-steel adhesive joints, a fracture mechanics model was calibrated to predict the strength of these joints, comparing the results with cohesive zone numerical models for the adhesive. Next, the fatigue behavior of the CFRP-metal adhesive bond with puddle iron plates taken from a 19th century railway bridge was studied, an S-N fatigue strength curve was obtained and a fatigue limit was proposed for the maximum principal stress in the adhesive. Finally, an innovative fatigue strengthening system using CFRP for the stringer-floor beam connections of the 19th century railway bridge was evaluated numerically and experimentally to reduce the stress level and to increase the fatigue life of the connection.