Finite Element Analysis of Corrosion and Bond-Slip

Abstract

Although reinforced concrete (RC) has an important advantage that it has virtue durability against an environmental attack, especially the resistance of corrosion of embedded reinforcements, due to the high alkalinity nature of concrete property, unfortunately, the problems of reinforcement corrosion still exist in many reinforced concrete structures. It has brought out many questions on the safety and serviceability of these corroded RC structures. Thus, it needs more effective approach for structural performance evaluation of the corroded structures. The residual capacity of the corroded reinforcement was determined through the evaluation of the volume increase of reinforcing steel and concrete crack propagation. The final determination of the service life of concrete structures was made based on the above evaluation results. Also, the effects of reinforcement corrosion on structural behaviours of RC members are investigated so that the reliable evaluation of structural performances of corroded RC members can be achieved by finite element method (FEM). The corrosion attack penetration has been given as a function of the time as input in the analyses. The load of corrosion applied inside the structural members can be modelled by the displacement around the circumferential surface between the reinforcing bars and concrete. The reduction of capability of the structures is determined from the corrosion level in the service years. Another complex phenomenon that governs concrete behaviour is the transfer of shear force across the interface by bond mechanism between concrete and steel reinforcement. It is a fundamental to most aspects of concrete behaviour. The bond mechanism is influenced by multiple parameters, such as the strength of the surrounding structures, the occurrence of splitting cracks in the concrete and the yielding of the reinforcement. However, when RC structures are analysed using the FEM, it is quite common to assume that the bond stress depends solely on the slip between the bars and concrete. In this the research the relationship of bond slip is also studied using FEM. An analytical study based on fracture mechanics was earned out to investigate the behaviour of three different types of specimens. In recent RC research, finite element modelling techniques have been developed to quickly evaluate the physical phenomena associated with cracking and bond. The non-linear finite element program ATENA with the non-linear material models for concrete, reinforcement bar and bond-slip is used to analyse cracking propagation and bond failure process. The influence between corrosion and bond slip in RC structure is also studied. Therefore, the understanding of serviceability of RC structure is improved. It was concluded that with the increase of load and the propagation of the crack, stress redistributed in the steel- continues until the specimen is damaged. The non-linear finite element fracture analysis shows that non-linear fracture mechanics can be effectively applied to investigate concrete fracture. Also, comparisons between the analyses of crack propagation and stress redistribution obtained using the finite element analysis was in good agreement with tests found in the literature.