预应力CFRP加固高强混凝土梁试验

通过四点弯曲试验进行了预应力碳纤维增强复合材料（CFRP）加固钢筋混凝土梁与无筋混凝土梁受力过程、破坏形态、延性以及梁底CFRP应变的对比性研究，并对0，0.15f_cfk，0.30f_cfk（f_cfk为抗拉强度标准值）3种预应力等级下的加固梁受弯性能进行了研究。结果表明:试验梁破坏形态均为接近中部弯剪裂缝引起的界面破坏；当CFRP预应力由0提高至0.15f_cfk，0.30f_cfk时，混凝土加固梁与钢筋混凝土加固梁提升基本一致，无筋混凝土梁极限荷载分别提高了8%和28%，钢筋混凝土梁极限荷载分别提高了10%和25%；随着CFRP预应力等级提高，加固梁底部的剥离破坏逐渐由树脂胶层的破坏转变成胶层与混凝土界面的破坏，预应力CFRP加固钢筋混凝土梁比无筋混凝土梁裂缝数量明显增多，裂缝开展速度缓慢，裂缝均分布于加固梁两侧，无筋混凝土加固梁裂缝主要分布于一侧，且钢筋混凝土加固梁延性有明显提高；与CFRP预应力由0提升至0.15f_cfk相比，CFRP预应力等级由0.15f_cfk提升至0.30f_cfk时梁底CFRP跨中应变提升幅度较大，CFRP利用率有了明显提升。

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The comparative studies of prestressed carbon fiber reinforced plastics (CFRP) reinforced concrete beams and non-reinforced concrete beams including mechanical process, failure pattern, ductility and beam bottom CFRP strain were carried out through the four-point bending test. The flexural performance of reinforced beam under three kinds of prestress levels of 0, 0.15f_cfk, 0.30f_cfk?(f_cfk?was CFRP tensile strength standard value) was studied. The results show that the failure modes of the test beams are all close to the interface failure caused by the middle bending shear crack. When the prestress level of CFRP is increased from 0 to 0.15f_cfk, 0.30f_cfk, the uplift of reinforced concrete beam is basically same to reinforced concrete beam, the ultimate load of unreinforced concrete beam is increased by 8% and 28% respectively, and the ultimate load of reinforced concrete beam is increased by 10% and 25% respectively. With the increase of CFRP prestress level, the stripping failure of strengthening beam bottom is changed from failure of resin lay into interface failure of glue layer and concrete. Compared to the plain concrete beam, the number of cracks of prestressed CFRP reinforced concrete beams increases obviously, crack propagation speed is slow, the cracks are uniform distributed in reinforcement beam on both sides, however the cracks of plain concrete beam are mainly distributed in a side, and ductility of reinforced concrete beam reinforcement has increased significantly. Compared with the CFRP prestress level increasing from 0 to 0.15f_cfk, when the CFRP prestress level increasing from 0.15f_cfk?to 0.30f_cfk, the mid span strain of CFRP beam bottom of is greatly improved, and the utilization rate of CFRP strengthened by prestressed CFRP is improved too.