无粘结预应力再生粗骨料混凝土梁力学性能

设计制作了5根不同粗骨料替换率的无粘结预应力再生粗骨料混凝土试验梁，并采用两点加载对其进行正截面受弯性能试验，研究了无粘结预应力再生粗骨料混凝土的梁破坏形态、承载力、裂缝宽度及跨中挠度等力学性能。基于试验数据建立了与《混凝土结构设计规范》（GB 50010—2010）相协调的无粘结预应力再生粗骨料混凝土梁预应力钢筋应力增量计算公式，提出了无粘结预应力再生粗骨料混凝土梁的最大裂缝宽度及刚度的设计建议。结果表明:再生粗骨料替换率对无粘结预应力再生粗骨料混凝土梁的破坏形态、裂缝宽度、跨中挠度影响不大；达到承载力极限状态时无粘结预应力再生粗骨料混凝土梁的无粘结预应力钢筋应力增量比无粘结预应力混凝土梁的无粘结预应力钢筋应力增量大，但再生粗骨料替换率对应力增量的影响不显著。

Mechanical Properties of Unbonded Prestressed Recycled Coarse Aggregate Concrete Beam

Five test beams of unbonded prestressed recycled coarse aggregate concrete with different replacement rates were designed and made. Then flexural performance tests of normal section were completed through two-point load. The mechanical properties, such as failure mode, bearing capacity, crack width and mid deflection and so on, were studied. Coordinated with Code for Design of Concrete Structures(GB 50010—2010), the calculation formulas of stress increment of prestressed bar for unbonded prestressed recycled coarse aggregate concrete beam were build based on test data. Meanwhile, the suggestions of maximum crack width and stiffness for unbonded prestressed recycled coarse aggregate concrete beam were put forward.The results show that the replacement rate of recycled coarse aggregate has non-significant influence on failure mode, crack width and mid-span deflection. Compared with unbonded prestressed concrete beam, the stress increment of unbonded prestressed bar for unbonded prestressed recycled coarse aggregate beam is larger, but replacement rate of recycled coarse aggregate has non-significant influence on stress increment of unbonded prestressed bar.