Fatigue performance evaluation of steel-UHPC composite orthotropic deck in a long-span cable-stayed bridge under in-service traffic

Ultra-high-performance concrete (UHPC) emerges as an advanced material that is promising to improve the fatigue performance of bridge decks. This study evaluates the fatigue performance of steel-UHPC composite deck in the Junshan Yangtze River Bridge, which is a long-span cable-stayed bridge, under in-service traffic loads. The bridge was instrumented with strain gauges that provided in-situ strain data at fatigue-prone details. The strain data of fatigue-prone details were used to evaluate the maximum and effective stress ranges and fatigue life of steel-UHPC deck. A finite element model was established to analyze stress distributions and validated by the in-situ strain monitoring data. The results showed that the UHPC layer significantly reduced the maximum stress ranges and the effective stress ranges of fatigue-prone details and increased fatigue life. Attention should be paid to rib splice joints in bridge inspection and maintenance because its maximum stress range exceeded the constant-amplitude fatigue limit by 40%.