Experimental Research On Creep Behavior Of Reinforced Concrete Beams Strengthened With CFRP Laminates

Carbon fiber reinforced polymer (CFRP) is a new type of material for civil engin- eering field, which is widely used to strengthen the RC members due to its advantages, such as high strength, light weight, corrosion free , fatigue resistance, convenience to construction and little influence to the physical apperence ,etc. At present, the experi- mental research for structures strengthened with CFRP focuses on the bending and shearing etc,but the creep research is limited . Aimed at the situation, the paper complete several aspects as following:(1) Long-term test on ten concrete columns with three different surface treatment of coat free, epoxy coated and CFRP sheet wrapped were completed. The creep properties of those concrete columns were studied. Two creep models from ACI209R(92) and CEB-FIP(MC90) were used to predict the time-dependent behavior of those concrete columns. The results showed that the creep coefficients in CFRP-confined concrete columns and in epoxy-coated concrete columns are almost same, both are less than that in plain concrete columns on the same other conditions but surface treatment ,which demonstrates that the creep reduction in CFRP-confined concrete columns is due to the existence of epoxy coating not of CFRP sheet.Furthermore,the physical apperence and dimension have litter effect on the creep behavior of CFRP-confined and epoxy-coated concrete columns.(2) Long-term test on twelve reinforced concrete simply beams were completed. The effects of adhering CFRP laminates, loading time and process of strengthening etc were studied. The results showed that the long-term deformations of beams strengthened with CFRP laminates are less than the deformations of plain beams by 6%～16.5% . On the same long-term load, with the process of strengthening changed, the creep deformations of strengthed beams were different.(3) Based on the rational assumptions, the method for computing short-term and long-term deformations of simply beams strengthened with CFRP laminates were deduced and programmed. The program considering the effects of steel on compression,creep of CFRP and delayed strain of CFRP were verified by test results.