Experimental Study On Flexural Behavior Of Concrete Beams Prestressed With AFRP Reinforcement

Concrete beams prestressed with Arimid fiber-reinforced polymer (AFRP) alternate to steel reinforcement have been a new field in civil engineering, so this dissertation's study is the first time in China.Modern prestressed concrete (pc) structures have been widely used in civil engineering. But because of corrosion of steel, the durability of those members prestressed with steel reinforcement is a problem. To solve this problem, fiber-reinforced polymer (FRP) tendons and reinforcing bars (rebars) have been developed to alternate to steel reinforcement in recent yeas. There are three kinds of FRP used in civil engineering: CFRP (Carbon FRP),GFRP (Glass FRP), AFRP (Aramid FRP). Because FRPs can offer improved corrosion resistance compared to steel, they will be widely used in civil engineering. This dissertation mainly studies flexural behavior of concrete beams prestressed with AFRP reinforcement, and the anchorage system of FRP reinforcing bars is studied too. AFRP reinforcement have two characteristics of short-term mechanical behavior compared to steel bars: (1) Tensile stress-strain curve is close to a straight line and have no yielded point; (2) The young's modulus is about one third of that of steel bars.This dissertation's experimental study and theoretics analysis are based on these two characteristics.8 simple-supported beams reinforced with AFRP reinforcement or steel strand have been tested in static vertical load experiment. The ratio and the prestressing force of AFRP reinforcement and steel reinforcement are concerned in experiment, and the cracking load, ultimate load, load-deflection curve, development of strain of AFRP reinforcement, development of crack, and assuming plane sections remain plane are investigated. Based on this investigation, the characteristic of concrete beams presterssed with AFRP reinforcement is obtained.The characteristic of concrete beams presterssed with AFRP reinforcement is discussed in next theoretics analysis. Based on Chinese "Code for design of concrete structures"(GB 50010-2002), the formula to calculate load-carrying capacity and short-term rigidity of these beams is deduced. Compared with the result of experiment, these formula are effective and accurate.