钢-超高性能混凝土组合桥面板钢筋布置对收缩效应影响OA

In steel-ultra-high performance concrete(UHPC)composite bridge decks,the significant early-stage shrinkage of UHPC induces substantial secondary forces in the structure due to the constraints provided by shear studs and embedded reinforcements,thereby degrading the mechanical performance of the composite deck.Based on an actual engineering project,shrinkage monitoring tests were conducted on composite deck specimens with different reinforcement ratios under natural ambient curing conditions.The developmental characteristics and spatial distribution of UHPC shrinkage,as well as the induced secondary internal forces,were analyzed,and the influence of reinforcement ratio on the shrinkage behavior was investigated.Furthermore,a shell-solid finite element model was established to conduct parametric analyses of reinforcement spacing and vertical position,revealing their influence on early-stage shrinkage behavior.The experimental and simulation results indicate that,under summer ambient curing conditions,the initial setting time of UHPC is approximately 15 h.The shrinkage develops rapidly at the early-stage and then gradually slows down,while the shrinkage strain in the edge regions of the bridge deck is significantly greater than that at the mid-span.When the reinforcement diameter increases from 12 mm to 16 mm,the peak early-stage shrinkage strain of the UHPC decreases by 34％,the maximum shear stress in the stud connectors decreases by 14.3％,and the stress in the steel top plate at the mid-span decreases by 13.9％,demonstrating that larger reinforcement diameters provide greater restraint against UHPC shrinkage.The parametric analysis further indicates that increasing the reinforcement spacing exacerbates UHPC shrinkage and the associated internal stress.The vertical position of the reinforcement has only a minor influence on the mid-span region,while elevating the reinforcement layer in the edge regions is beneficial for decreasing UHPC shrinkage strain.Under comparable reinforcement ratios,increasing the reinforcement diameter is more effective than decreasing the reinforcement spacing in controlling UHPC shrinkage and reducing secondary internal forces.These findings provide theoretical support for the rational design of reinforcement in steel-UHPC composite bridge decks.