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 insitu 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%.