体外预应力CFRP筋加固T形截面混凝土梁受弯性能试验研究

Experimental study on flexural behavior of concrete T-beams strengthened with externally prestressed CFRP tendons

通过体外预应力CFRP筋加固T形截面混凝土梁静力试验,研究体外预应力CFRP筋加固梁的受弯性能,包括受力过程、破坏形态、延性及CFRP筋应力增量等,分析张拉控制应力、非预应力配筋率和混凝土强度等级对加固梁受弯性能的影响。结果表明:与未加固梁相比,采用体外预应力CFRP筋加固,能显著提高混凝土梁的受弯承载力、整体刚度和极限变形能力,限制裂缝发展;张拉控制应力和非预应力筋配筋率对加固梁受弯承载力影响较为明显,而混凝土强度等级影响较小。基于试验结果,运用现有体外预应力混凝土结构理论,建立了体外预应力CFRP筋加固T形截面混凝土梁受弯承载力计算公式,可供实际工程设计参考。

In this study,a static experiment on RC T-beams strengthened with externally prestressed CFRP tendons was carried out. The flexural behaviors of strengthened beams,including loading process,failure mode,ductility and stress increment of CFRP tendon,were studied. The influences of tension control stress,the reinforcement ratio of nonprestressed rebar,and concrete strength grade on their flexural behaviors were analyzed. The test results show that flexural bearing capacity,overall stiffness and ultimate deformability of strengthened beams may be improved more significantly than unstrengthened beams,and the development of cracks can be restrained by external prestressing CFRP tendons. It was observed that the tension control stress and the reinforcement ratio of non-prestressed rebar have remarkable influences on the flexural bearing capacity of strengthened beams,but the influence due to concrete strength grade is much less. Based on test results and existing theory of externally prestressed concrete structure,the calculation formula for flexural bearing capacity of concrete T-beams strengthened by external prestressing CFRP tendons was established,which may provide a reference for practical engineering design.