A new empirical model for flexural stiffness of corroded post-tensioned concrete beams

Under service loading and environmental actions, the corrosion of steel strands would reduce the cracking load and ultimate load of post-tensioned concrete (PTC) beams. It also leads to the degradation of flexural stiffness, and hence increases the deflection of beams under the same load. In order to more effectively evaluate the stiffness degradation of corroded post-tensioned concrete (CPTC) beams, an empirical model is proposed in this work for assessing the stiffness considering the effect of the corrosion of steel strands. In the proposed model, cracking stiffness and stiffness after cracking are assessed separately, and the equations of cracking moment and ultimate moment are derived. The proposed model is verified by experimental data. Results show that the proposed model can efficiently predict the stiffness changes during the whole loading process, and the deflections predicted by the proposed model are in good agreement with experimental values. The proposed model is proved to be able to efficiently predict the stiffness degradation of CPTC beams caused by corrosion of steel strands, and can reveal the dependence of flexural stiffness on the corrosion loss of steel strands and the external loads.