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通过对6根采用CFRP布与钢板复合加固的钢筋混凝土梁和2根未加固梁进行静载和等幅疲劳试验,研究了粘贴CFRP布和钢板加固对钢筋混凝土梁受弯疲劳性能的影响和作用。试验中对比了加固与未加固试件的破坏形态、跨中挠度、应变发展等情况,分析了在不同的疲劳荷载上、下限作用下复合加固梁的挠度和疲劳寿命等。结果表明:复合加固后试件的疲劳变形有所减小,复合加固梁的跨中挠度、残余挠度和各材料应变均随疲劳循环次数的增加呈现三阶段发展规律,且均随着疲劳循环次数及疲劳荷载幅值的增大而增大;循环荷载引起材料的累积损伤,使复合加固梁在200万次循环荷载后的静载受弯承载力和延性均有下降。与未加固梁相比,复合加固梁显著降低了钢筋的应力和应力幅,破坏始于钢板断裂,此后梁仍可继续承受1~2万次循环荷载才发生钢筋断裂,破坏时表现出双重保护机制且疲劳寿命得到延长。疲劳荷载幅值越低,钢板的应力幅越小,梁的疲劳寿命越长。
Through the static load and equal amplitude fatigue test of six reinforced concrete beams and two unreinforced beams reinforced by CFRP cloth and steel plate, the effect and effect of CFRP cloth and steel plate reinforcement on flexural fatigue behavior of reinforced concrete beams are studied. . The failure morphology, mid-span deflection and strain development of strengthened and unreinforced specimens were compared in the test. The deflection and fatigue life of composite reinforced beams under different upper and lower fatigue loads were analyzed. The results show that the fatigue deformation of specimens decreases with the increase of fatigue cycles. The mid-span deflection, residual deflection and strain of each material show a three-stage development pattern with fatigue cycles increasing. And the increase of fatigue load amplitude. The cumulative damage caused by cyclic loading causes the composite beam to have a lower static load capacity and ductility after 2 million cyclic loadings. Compared with the unreinforced beam, the composite reinforcement beam significantly reduces the stress and stress amplitude of the rebar, and the failure starts from the fracture of the steel sheet. After that, the beam can continue to withstand 1 ~ 200,000 cycles of load to break the rebar, thus showing double protection Mechanism and fatigue life has been extended. The lower the fatigue load amplitude, the smaller the stress amplitude of the plate, the longer the fatigue life of the beam.