Experimental Study On The Performance Of Lap-spliced Reinforcement In Reactive Powder Concrete

High-performance reinforced concrete structures formed of Reactive Powder Concrete(RPC)and Carbon Fiber Reinfoced Plastics(CFRP)can solve the problem of self-importance and poor crack resistance of reinforced concrete structures.That high-performance reinforced concrete structures is suitable for overcoming the corrosion issue posed by ordinary steel bars in reinforced concrete.In the reinforced concrete structures,the length of the reinforcement is unavoidable,and the use of lap is the easiest.For the lap-spliced behavior of steel bars or CFRP bars,most of the current researches focus on ordinary concrete.However,there is little research on the lap-spliced behavior of steel bars or CFRP bars in RPC,which limits the promotion and application of RPC and CFRP.Therefor,this paper studied the lap-spliced behavior of steel bars or CFRP bars in RPC under the supprot of the National Key Research and Development Program of China “ Key Technology Integration and Demonstration for the New Structural Application of Fiber Reinforced Composites”(No.2017YFC0703008).The main contents are as follows:(1)Tensile tests were conducted on 39 specimens with lap-spliced ribbed steel bars in RPC including the test parameters of the splice length,RPC strength,space between the lap-spliced ribbed steel bars and stirrup ratio.The results show that: two failure modes,pullout and fracture of the lap-spliced ribbed steel bars,separately,were found in those specimens.As for those specimens with failure mode of pullout,the bond strength on the surface of the lap-spliced bars decreases a little with the increasing of the splice length,and increases with the RPC strength and stirrup ratio increased.Compared with the result of specimen with a splice length of 100 mm,the bond strength of the specimen with splice length of 150 mm decreases about 5%.The equations for predicting the average bond strength and the critical splice length of the lap-spliced bars were established based on the test results,and their feasibility was verified by the test results from the third party.(2)Tensile tests were conducted on 27 specimens with lap-spliced CFRP bars in RPC including the test parameters of the splice length,RPC strength and stirrup ratio.The results show that: two failure modes,pullout and fracture of the lap-spliced ribbed CFRP bars,separately,were found in those specimens.As for those specimens with failure mode of pullout,the bond strength on the surface of the lap-spliced bars decreases a little with the increasing of the splice length,and increases with stirrup ratio increased,the RPC strength has no significant effect on the bond strength.The equations for predicting the average bond strength and the critical splice length of the lap-spliced bars were established based on the test results.(3)Based on the stress-slip curves of steel bars or CFRP bars in RPC during the test,the Adaptive Network-based Fuzzy Inference System(ANFIS)was established.Predict the stress-curve of steel bars or CFRP bars in RPC based on ANFIS,and analyze the influence of each parameter on the lap-spliced behavior.The results show that the bond strength of steel bars in RPC decreases a little with the increasing of the splice length,and increases with the RPC strength and stirrup ratio increa sed;the bond strength of CFRP bars in RPC decreases a little with the increasing of the splice length,and increases with stirrup ratio increased.