Application and performance of UHPC–SMA bonding system in steel bridge deck pavements under temperature effects

The interfacial shear performance between ultra-high performance concrete (UHPC) and stone mastic asphalt (SMA) plays a critical role in determining the service performance of steel–UHPC composite bridge decks. To investigate the interfacial static and fatigue behavior of the UHPC–SMA system, inclined shear static and fatigue tests were conducted under varying temperature conditions. Based on the experimental results, a temperature-dependent Δτ–Nf shear fatigue life prediction model was developed. In addition, an interfacial fatigue damage evolution model based on shear stiffness degradation was proposed. The proposed models were validated through finite element analysis and subsequently applied to a composite pavement segment model of a steel bridge deck to examine the damage evolution of the interfacial interlayer under vehicular loading. The static and fatigue test results indicate that increasing temperature significantly reduces the interfacial shear strength, shear stiffness, and fatigue life of the UHPC–SMA system. The finite element results further show that interfacial degradation leads to an increase in the principal stress in the UHPC layer, as well as a slight increase in the principal stress at the weld toe of the steel–UHPC composite deck.