Model for Flexural Strength Calculation of Corroded RC Beams Considering Bond-Slip Behavior

An analytical model is proposed in this paper to evaluate the residual flexural strength for corroded RC beams. The steel slipping caused by bond degradation is included in the proposed model. Various failure modes of beams caused by different types of steel bar anchorage are also incorporated in the model. The bond degradation is considered as a function of the corrosion rate of steel. Bond degradation transfers prematurely the effective bond force, resulting in incompatible strain within the slipping region. A new method is developed to quantify the slipping region based on the transfer theory of effective bond force. Next, a new strain-incompatibility analysis method is proposed to determine the deteriorated flexural strength. The accuracy of the model is validated by experimental observations on the beams with different steel anchorage under corrosive environments. Results show that the proposed model can provide a reasonable prediction for the flexural strength and failure modes. The strain incompatibility of the corroded beams is sensitive to corrosion loss and loading position. It becomes very significant for the beams with a corrosion loss greater than 7% and the beam with a concentrated load at the midspan.