Preventive Fatigue Strengthening of Steel Structures with Bonded CFRP—Efficiency Demonstration on a Real Bridge

An important objective of sustainable development applied to bridge infrastructure is to develop and deploy effective strengthening solutions, with a view to increasing the service life of existing structures. Steel bridges are prone to fatigue and their remaining service life can be evaluated after careful diagnosis of induced structural damages. However, it is generally difficult to assess the extend of damage caused by fatigue at an early stage before crack initiation. Besides, old structures are particularly vulnerable to fatigue as old steels exhibit a rather brittle behavior, but most design codes did not take into account fatigue effects before the 1970s. To address these issues, an assessment method and a preventive strengthening solution based on the use of adhesively bonded UHM (Ultra-High Modulus) CFRP (Carbon Fiber Reinforced Polymer) plates were developed and applied to an existing bridge for validation (Jarama bridge owned by the Community of Madrid in Spain). Strain measurement collected during load tests was analyzed to verify that the reinforcement works according to theoretical expectations, and different parameters were studied such as the influence of low traffic during CFRP installation. In the end, this field demonstration provided clear evidence of the efficiency of the developed solution.