In recent years, evaluation of deterioration and aging effects on seismic performance assessment of existing reinforced concrete structures has been paid much attention in earthquake and structural engineering community due to economical and safety issues. Corrosion of concrete reinforcement causes changing of nonlinear behaviour of reinforced concrete structures and ignoring these changes may lead to structural damage during the design life time of RC structures. Investigation of reinforcement corrosion effects in concrete structures on nonlinear behaviour of reinforced concrete members is the main subject of this research. In this study, the structural behaviour of the moment-curvature curve was investigated under these corrosion effects. After occurring the corrosion, cross section of the reinforcement is gradually reduced and consequently load bearing capacity of the reinforced concrete members will be reduced significantly. Accordingly, the relationship between corrosion and moment-curvature curve of structural members will be discussed. A two-dimensional frame is considered to investigate the seismic behaviour of structural frame and members, under different scenarios of corrosion in comparison with the approach proposed by Instruction for Seismic Rehabilitation of Existing Buildings (No. 360). Based on these results, to take the corrosion effects into consideration, it is recommended to use a k factor associated to ultimate sectional capacity instead of ductility limit.