体外配置CFRP预应力筋RPC梁抗弯性能试验研究

方志 黄正猛 贾理

摘   要：为研究体外配置碳纖维（Carbon Fiber Reinforced Polymer，CFRP）预应力筋活性粉末混凝土（Reactive Powder Concrete，RPC）梁的抗弯性能，以剪跨比、张拉控制应力及预应力度为试验参数，进行了4根体外配置CFRP预应力筋RPC梁抗弯性能试验. 基于试验结果，明确了梁的受力破坏特征，推导了梁的开裂弯矩、极限弯矩计算公式并以试验结果验证了其适用性. 结果表明：梁内未配置任何普通钢筋、预应力度为1.0的全预应力梁，均发生少筋特征的脆性断裂破坏，增大张拉控制应力可提高全预应力梁的开裂荷载，但不改变其破坏形态;梁内配置普通钢筋、预应力度为0.71的部分预应力梁，其承载能力及极限变形较预应力度为1.0的全预应力梁分别提高88.7%和18.1%，破坏模式为梁内非预应力钢筋屈服、受压区混凝土压碎的延性破坏. 钢纤维的掺入对全预应力梁抗弯性能的提升作用有限，普通钢筋的配置对体外CFRP预应力RPC梁受弯性能的改善作用显著，因此实际工程中不宜过高估计钢纤维的作用而取消体内非预应力钢筋的配置.

关键词：RPC;体外预应力;CFRP;梁;抗弯性能

中图分类号：U443.35                               文献标志码：A

Abstract：In order to investigate the flexural behavior of Reactive Powder Concrete（RPC） beam with externally prestressed Carbon Fiber Reinforced Polymer（CFRP） tendons，four beams specimens with different shear-span to depth ratios， tension control stress of the tendons and partial prestressing ratios（PPR） were tested. Based on the experimental results，the failure patterns of the beams were clarified， and the equations for predicting the cracking and ultimate moments of the beams were proposed and verified. The results show that the failure mode is similar to the under reinforced RC beams for all fully prestressed beams of PPR 1.0 without any internal steel reinforcements. Increasing the tension control stress of the tendons could enhance the cracking load of the fully prestressed beams，but could not change the failure mode. Compared with the fully prestressed beams， the ultimate capacity and ultimate deformation of the partially prestressed beam with steel reinforcements（PPR 0.7） increase by 88.7% and 18.1%， respectively. The ductile failure mode with the yielding of steel bars followed by the crush of RPC in compression zone was observed in the partially prestressed beam. The steel fibers in RPC have a limited effect on the flexural performance of the fully prestressed beams， while the steel reinforcements might improve the behavior of the beams significantly. Therefore，it is not suitable to overestimate the role of steel fibers and remove the use of non-prestressed reinforcements in the RPC beams.

Key words：RPC;external prestress;CFRP;beam;flexural behavior

混凝土结构已成为当今世界土木工程中最主要的结构形式，但普通混凝土结构普遍面临结构自重大、易开裂、耐久性仍显不足等问题. 因此，寻求一种更为有效的配筋混凝土结构以降低结构自重、增强结构耐久性，对土木工程的发展具有重要意义.

基于最大密实度原理配制的活性粉末混凝土（Reactive Powder Concrete，RPC），具有超高的抗压强度……