重复超载嵌入式FRP加固混凝土T形梁的研究

Study of Reinforced Concrete T Beams Strengthened with Near Surface Mounted FRP Under Repeated Overloading

采用重复超载模拟桥梁的带缝工作状态,通过6根T形梁试验,研究了嵌入式FRP加固梁的破坏形态、内力和变形特征等力学性能,讨论了超载程度和加载次数对加固梁性能的影响.结果表明,在超载条件下,嵌入式CFRP板加固可以提高钢筋混凝土T形梁的抗弯极限承载力和刚度,增大了延性系数.不同超载程度和重复加载次数对加固梁极限承载力无明显影响,加固梁跨中截面挠度随超载次数的增加而减小.当超载程度在一定范围内时,不会引起加固梁跨中截面挠度的改变;当超载程度超过一定限度时,超载程度加大将导致加固梁的跨中截面挠度明显减小.对于重复超载作用下的带裂缝适筋梁,按照现有FRP加固理论进行设计是偏于不安全的,需要进行承载力修正.

In order to recognize the effects of cracked degree and the strengthening parameters on the performance of reinforced concrete beams,6 T-section pre-cracked reinforced concrete beams strengthened with near surface mounted CFRP sheets were tested.The failure modes,the bending moments and deflections of the strengthened concrete beams were discussed.The results showed that the reinforcements by using the near surface mounted CFRP sheets have an obvious impact on the flexural ultimate bearing capacities.The pre-cracked degree has a few influences on the ultimate bearing capacities and the failure modes of the strengthened concrete beams,but splits in the beams developed by pre-cracked process can produce more deflection of the pre-cracked beams.The more fissures are induced,the larger deflection is.The failure modes of all the beams strengthened with CFRP sheets are the debonding of CFRP sheets from the adhesive layer of epoxy.The bending performance of the strengthened beams can be in a good state if reliable shear strengthening can be assured.