Evaluation of the Reinforcement Effect of Steel-UHPC Composite Deck with Steel Strips

The steel-UHPC composite deck is an advanced measure to improve the fatigue resistance of orthotropic steel decks. However, there are penetrating cracks on the steel panel in some bridges. In this case, the penetrating cracks would cause reflective cracks in the UHPC if the UHPC was in direct contact with the penetrating cracks. To ensure the good mechanical performance of the UHPC layer and avoid reflective cracks, this study proposes a reinforcement scheme of steel-UHPC composite deck with steel strips. The good performance of the reinforcement scheme was verified by finite element analysis and field tests. Firstly, the basic information of a long-span cable-stayed bridge and the reinforcement scheme was introduced. Secondly, the global and local mechanical performance of the bridge after reinforcement are analyzed by finite element analysis. Finally, the performance of the steel-UHPC composite deck in improving the fatigue resistance of the orthotropic steel decks was verified by field test. The results show that: (1) Overall stress state of the bridge is basically unchanged and has a large safety reserve after the downstream deck of the bridge was reinforced. (2) Tensile stress of the UHPC layer is greatly influenced by penetrating cracks. After adding steel strips, the crack risk of the UHPC layer is greatly reduced. (3) After reinforcement, the effective stress ranges of fatigue-prone details are reduced, and the stress ranges of fatigue-prone details are lower than the constant-amplitude fatigue limit. The reinforcement scheme effectively improves the fatigue resistance and reduces the crack risk of fatigue-prone details. In a word, the reinforcement scheme of the steel-UHPC composite deck with steel strips is an advanced measure to reduce the crack risk of the UHPC layer and improve the fatigue resistance of orthotropic steel decks.