In the aftermath of earthquakes, it rests with engineers to assess the implications of the damage to structures and to identify the necessary repair work; such assessment requires the use of non-linear analysis of reinforced concrete structures. Many finite element procedures based on different material models are available, however, most of them have been checked only for specific applications of load fluctuation and reversal. This state of the art report provides a thorough review of all the available knowledge in the area of constitutive modelling of concrete, reinforcing steel, bond and interaction. It discusses the problems encountered in assembling the various elements to achieve an appropriate model, relevant to the loading spectrum, and considers the various solution strategies for the numerical integration of non-linear equations.