Experimental Study Of Bending Behavior Corroded Reinforced Concrete Beams

Steel corrosion is one of the main factors in respect of durability of concrete. Concrete structures may bear not only static or repeated loading, but also cyclic loading in practical engineering.In order to study the bending behavior of reinforced concrete(RC) beams after steel was corroded, computing model of flexural capacity under repeated loading was established based on test results with test samples of 4 non-corroded reinforced concrete beams and 16 corroded RC beams. The test included two phases: The first one was the electrolyte accelerated corrosion of the sample beams and the second one, the repeated loading to the corroded beams. Computation model for cracking moment and flexural stiffness of corroded beams under repeated loading was established. Effect of steel corrosion on reinforced concrete beams regarding cracking, mid-span deflection, stiffness, bearing capacity and the failure mechanism of corroded beams were studied. Impact of corrosion on Bond strength degradation as the key point was researched to found the computing model of flexural capacity under cyclic loading.Finally, standards of different countries were listed, and several commonly used measures to prevent corrosion were introduced. Based on the research work of this study, following primary findings are obtained:(1) In the mild steel corrosion, effect of bond stress changing to bearing capacity can be approximately regarded as in positive direction, the more bond stress improved, the more bearing capacity increased.(2) Carrying capacity increased when steel corrosion rate was less than 2%. But the bearing capacity began to decline when corrosion rate was increased to a degree greater than 2%, This was demonstrated, during both repeated or cyclic load. (3) Compare with the non-corrosive beams, bond stress of corroded beams will still increase although steel corrosion rate was increased to 5%.(4) Component cracking moment increased under lower corrosion rate(lower than 5%); the beneficial effects never disappear gradually until corrosion rate is higher; corrosion rate further improve(greater than 5%), would have a negative impact on component cracking moment.(5) When Faraday's law was used to calculate the test time of electrolyte accelerated corrosion, the actual corrosion rate would be lower. That's because the interference of other factors such as stirrups. Therefore the law needs some improvements.