预张碳板加固已承受荷载的RC梁弯曲试验

Flexural Behavior of RC Beams Strengthened with Pretensioned CFRP Laminate under Loading Conditions

研究目的:根据外贴纤维增强聚合物(fibre reinforced polymer,简称FRP)片材加固已受荷载作用的RC梁加固材料FRP强度利用率不高、正常使用阶段性能改善不佳等缺点,首先对混凝土梁施加一定的初始荷载,然后对碳纤维增强聚合物(CFRP)薄板施加预应力再锚固并粘贴于混凝土梁受拉面,研究预应力、混凝土梁初始受荷状态等参数对试验梁弯曲性能的影响;对比预应力CFRP板加固构件与普通外贴CFRP板加固受弯构件的承载力、跨中挠度及应变、裂缝扩展情况等,指出预应力碳纤维薄板加固混凝土桥梁方法的可行性和优越性。研究结论:(1)与外贴加固梁相比,预应力CFRP板加固后混凝土梁的屈服荷载、极限荷载分别提高了15.5%和10.5%;(2)位移延性比未加固的基准梁略有降低;(3)纯弯段裂缝间距相对更小,可有效抑制裂缝的扩展,改善混凝土梁使用阶段性能;(4)本研究成果可供桥梁加固研究及应用参考。

Research purposes： Externally bonded （EB） fiber reinforced polymer（FRP） method has some shortcoming, such as poor intensity of utilization of FRP and performance improvements during normal use for reinforced concrete beams. Impose certain initial load on concrete beam first, then the carbon fiber reinforced polymer （CFRP） laminate is prestressed, anchored and pasted in the concrete beam bearing surface, the effect of prestress and initial state of the concrete beam on the bending property of the test beam is studied. Comparison of the bearing capacity, midspan deflection, crack propagation of pretensioned CFRP laminate strengthening member and common CFRP laminate flexural member, feasibility and superiority are pointed out for pretensioned CFRP laminate strengthening method for concrete bridge. Research conclusions： （ 1 ） The pretensioned CFRP can improve the performance of the beams, and enhance yield load and ultimate load by 15.5% and 10.5% compared with RC beam strengthened with externally bonded CFRP laminate under sustained loading. （2） Displacement ductility is slightly lower than the benchmark beam without reinforcement. （3） The crack spacing of pure bending section is relatively smaller, which can effectively inhibit the expansion of the crack, improve the concrete beam using stage performance. （4）The research results can provide references for RC girderstrengthening study and application.