碳纤维筋体外预应力加固钢筋混凝土梁的疲劳性能

Fatigue performance of RC beams strengthened with externally prestressed CFRP tendons

通过碳纤维筋体外预应力加固的钢筋混凝土梁疲劳试验,研究了加固梁的疲劳破坏模式及抗疲劳性能。结果表明:碳纤维筋体外预应力加固钢筋混凝土梁发生疲劳破坏时,钢筋及体外筋均未疲劳断裂,而是上缘受压区混凝土疲劳压碎;在疲劳荷载水平S<0.43时,碳纤维筋应变随疲劳次数的增加增幅不明显;当S>0.43时,碳纤维筋应变明显增加;在经历一定次数疲劳加载后,钢筋应变、混凝土应变与荷载呈非线性关系,而碳纤维筋的应变与荷载依然呈线性关系;在同一静载作用下,疲劳次数越大,钢筋应变、混凝土应变及碳纤维筋应变越大;与未加固的钢筋混凝土梁比,加固梁(S=0.48)疲劳寿命可提高30%。

The fatigue failure mode and anti-fatigue performance of Carbon Fiber-reinforced Polymer （CFRP） post-tensioned beams are systematically studied by fatigue test. The results show that, when fatigue failure occurs, there are no fractures on the steel bars and the external prestressed tendons, but the upper concrete is crushed. With the increase in the number of fatigue loading times, as the fatigue loading level S〈0. 43, the growth of CFRP tendon strain does exist but is not obvious; however, as S〉0.43, CFRP tendon strain increases significantly. After certain number of fatigue loading times, the relationships between the steel strain, the concrete strain and the loading are nonlinear, indicating that the beams are damaged due to fatigue; while the relationship between the strain of CFRP tendons and the loading is linear. Under the same static loading, the higher the number of fatigue loading times is, the larger the strains of the steel bars, the concrete and the CFRP tendons are. Compared with the common steel reinforced concrete beams, when S=0.48 the fatigue life of the CFRP post-tensioned beam is increased by 30 %.