Flexural Behavior Of Reinforced Concrete Beams Strengthened With NSM Anchorage Clamping CFRP Plates

Carbon Fiber Reinforced composite(CFRP)has been widely used in strengthening concrete structures due to its light weight,high strength,fatigue resistance and corrosion resistance.There are two kinds of CFRP reinforcement technologies according to the position of materials: external bonding method and embedded method.Because embedded method is to embed CFRP into the concrete interior,it can greatly reduce the loss of external environment to the reinforcement materials,and has good fire performance,so it has a broad application prospect.At present,domestic and foreign scholars have conducted experimental and theoretical studies on the internal embedded CFRP reinforcement method,and found that the slot size,slot spacing and the quality of the glue have a great impact on the failure mode and reinforcement effect of the specimen,which to some extent limits the engineering application of embedded reinforcement method.Therefore,a new method of strengthening reinforced concrete beams with embedded anchors clamping CFRP plates is proposed in this paper to study the flexural properties of reinforced concrete beams after reinforcement.The main research contents and conclusions include the following aspects:(1)A new type of anchor is designed,including clamping single plate type anchor and clamping double plate type anchor,and it is verified through the test that the anchor can provide reliable clamping force.(2)Considering the reinforcement method,the amount of CFRP reinforcement and the construction technology and other factors,12 reinforced concrete beams were tested for their flexural performance,and the following conclusions were obtained: the reinforcement effect of the embedded anchorage method is roughly the same as that of the ordinary embedded reinforcement method,and the construction period is effectively shortened;Increasing the amount of CFRP reinforcement is beneficial to improve the utilization efficiency of CFRP under the premise that the reinforced beams are not damaged by superbars.When the method of embedded anchorage is adopted,the filling material in the slot can prevent the CFRP from being damaged in advance and improve the ultimate bearing capacity of the strengthened beam.(3)The formulas for calculating the flexural capacity,deflection and crack of the normal section of reinforced concrete beam strengthened by CFRP plate with embedded anchor are put forward,and the results are compared with the test results to verify that the formulas have good applicability which can provide reference for practical reinforcement projects.