Corrosion-induced flexural behavior degradation of locally ungrouted post-tensioned concrete beams

Strand corrosion within the insufficient grouted duct has become a serious problem affecting the durability of bridge structures. The residual flexural behavior of the locally ungrouted post-tensioned concrete beams after strand corrosion is investigated in the present study. Two experiments are performed: corroded strand test for the constitutive law development and beam test for the flexural behavior investigation. An analytical model is proposed to predict the ultimate strength, the deformation, and the strain response of corroded beams under external loadings. The proposed model considers the strain compatibility between strand and concrete, material mechanics deterioration of strand, and the asymmetric deflection due to local corrosion in ungrouted duct. The accuracy of the model is verified by the experimental observations. Results show that corrosion loss has less effect on the yield strength and elastic modulus than that on the ultimate strain of strand. It is also observed that light corrosion has little effect on the beam cracking and the load-deflection behavior before beam cracking. Severe corrosion degrades significantly the flexural capacity and the local post-cracking stiffness of beams, which leads to the asymmetric deformation and crack formation.