通过理论分析和试验,研究高强纤维片材(FRP)抗弯加固钢筋混凝土(RC)梁中FRP应变随构件变形及外加荷载的变化规律以及FRP的极限剥离应变。结果表明:FRP应变与RC梁的挠度成线性关系,与FRP粘贴长度基本无关,且不受混凝土开裂和钢筋屈服的影响;经FRP加固后RC梁的极限变形量明显减小,构件的延性能力有所降低;在给定试验条件下,FRP加固的RC梁的承载力提高约32%,钢筋屈服前承载力的增加量约占承载力总增加量的64%;FRP极限剥离应变约为8.117×10^-3,剥离时相对应的RC梁挠度为1.01×10^-3L^2/h(L为梁长,h为梁高)。由于实际加固桥梁的跨度较大,允许挠度较小,因此FRP的应变水平较低,其高强性能得不到充分发挥。
Based on theory analysis and a series of model tests,the relationships between fiber reinforced polymer(FRP) strain and the deflection/loading were discussed,and the FRP debonding strain was also analyzed.The results show that FRP strain is linear to the deflection of RC beam,and the FRP length and the crack of concrete or the failure of reinforcement have no obvious influence on this rule.FRP can reduce the ultimate deflection of RC beam,while the ductility of RC beam strengthened with FRP declines.The load-bearing capacity of the RC beam is increased by FRP with large amplitude of 32% in this test,and at the yield point of steel reinforcement,the increase of the load-bearing capacity is about 64% of the total increment.FRP ultimate debonding strain is about 8.117×10^-3.When FRP debonding,the deflection of RC beam is 1.01×10^-3 L^2/h(L is the span of RC beam,h is the height of RC beam).The spans of the service bridges are larger while the allowable deflections are smaller,so FRP strain is smaller.As a result,the high strength performance of FRP can not be fully exerted.