Evaluation of Load Carrying Capacity of Corroded Rc Beams

Abstract

In most cases, reinforced concrete structure is durable and strong, performing well throughout its service life. However, in some cases, it does not perform adequately due to various reasons, one of which is the corrosion of the embedded steel bars used as reinforcement. RC beam affected by corrosion witnesses various degradation problems which affect its load carrying capacity. These degradation problems include loss of bond between reinforcement bars and the surrounding concrete, loss in area and strength of the rebar and cracking or spalling of concrete cover. In this work, an attempt has been made to study appropriate 3D-FE model for evaluating load-carrying capacity of both control and corroded beams analytically. In the present study, experimental programme has been carried out. In which 10 Beams of 1300mm*150mm*150mm were cast using a common concrete mix, out of which 4 beams were earmarked as control beams that were not subjected to corrosion and the remaining 6 beams were subjected to corrosion by impressed current. However, testing (four-point bending test) of few beams were not able to perform due to pandemic situation. Out of six beams which was supposed to be subjected for accelerated corrosion, only three beams were able to subject for accelerated corrosion and NDTs (ER, HCP & UPV) were perform on those beams. ER readings were taken using different probe configuration to minimise errors in results due to presence of rebar. For the conducted experimental programme, analytical study using 3D-FE modelling in ABAQUS software have done to know the load-carrying capacity of control, Corroded, CFRP-Control, CFRP-Corroded beam specimens. Prior to develop a model for the beam affected by corrosion, various FE models were constructed first for control beam in ABAQUS software to study the competence of selected material models from the literature. Co-relation between FE and the available experimental results of the selected beam indicates that use of surface-based cohesive behaviour, which is a mechanical model based on traction-separation behaviour, is accurate for modelling the bond in 3D-FE model of RC control and corroded beams. This study has prepared a three-dimensional (3D) FE model using ABAQUS software to simulate the behaviour of corrosion in RC beams, by including possible all corrosion-induced damages like bond loss, cracking of concrete, and reduction in steel area and strength. Validation of the prepared model have been done with experimentally available beam results. It was found that results of FE and experimental load deflection curves were identical within 15-20% accuracy. Almost, entire procedure of modelling of control and corroded beams were converted in the Python algorithm to make modelling procedure less cumbersome in ABAQUS software.