A Study on the Flexural Performance of UHPC Precast Deck-Joint Interface by the Exposure of Steel Fiber

As a solution against the serviceability problem caused by the cracks occurring at the UHPC precast deck-joint interface, this study proposes a method exposing the steel fiber at the interface and evaluates the corresponding flexural performance of the lap spliced construction joint. After having slowed down the strength development of the concrete placed in the joint of the precast deck by means of a curing retardant, the concrete at the interface is crushed so as to expose the steel fibers and the change in the flexural performance is observed experimentally according to the exposure of the steel fibers. The results show that, even if the ultimate strength and stiffness of the UHPC precast deck including the joint are mostly determined by the arrangement details of the rebar lap splice, the exposure of the steel fibers can secure stable ductile behavior and reduce the width of the cracks generated at the precast deck-joint interface under service load.

超高性能混凝土-混凝土组合简支梁弯曲性能试验

进行了3根超高性能混凝土(UHPC)位于受拉区的超高性能混凝土-混凝土组合梁(UHPC-NC组合梁)和1根普通钢筋混凝土梁的弯曲性能试验。对UHPC-NC组合梁的受力过程、跨中截面应变分布、裂缝开展模式和破坏形态等进行了研究分析。试验结果表明,UHPC-NC组合梁在加载过程中基本符合平截面假定,并且在UHPC层中配置适量的纵向钢筋,能大幅度提高组合梁的抗弯承载力。同时,将钢筋和UHPC对试验梁极限承载力的贡献分为4个阶段(初始状态、阶段状态、极限状态和破坏状态)进行计算。最后,对组合梁受拉区UHPC层等效矩形应力系数k进行推导。结果表明,UHPC层对组合梁抗弯承载力的贡献效率随着配筋率的不同而不同。