Analysis of the failure of interstate 10 freeway ramp during the Northridge earthquake of 17 January 1994

The response of a reinforced concrete freeway structure damaged during the Northridge earthquake is determined using non‐linear dynamic finite element analysis. The results obtained allow the ability of contemporary analysis techniques to predict the seismic response of such structures to be assessed and the critical aspects of the behaviour of the structure to be identified. Comparison is made with the response predicted using equivalent static analysis and more simplified dynamic analysis, from which the results of the more advanced analysis are shown to be superior. The influence of a number of modelling assumptions, principally with regard to boundary conditions, on the computed response is also assessed. From this, the disparity between the design conditions and those actually pertaining at the time of the earthquake are seen to play a crucial role in the mode of failure of the structure. It is concluded that, upon the development of an accurate structural model, the analytical results correlated well with the behaviour observed in post‐earthquake reconnaissance.