Non linear finite element analysis of a 50 years old reinforced concrete trough bridge
Résumé
In this paper, a nonlinear finite element model of a full scale bridge (Örnsköldsvik bridge, Sweden) is presented in connection with load tests. In order to quantify the carrying capacity of the bridge, a collapse load test was performed within the European Union founded project "Sustainable Bridges - Assessment for Future Traffic Demands and Longer Lives". The finite element model introduces new constitutive material models. Four materials are in particular modelled in accordance with the bridge characteristics: concrete, steel reinforcement bars, CFRP bars and steel/concrete interface. The concrete is described by a damage mechanics based model developed within the framework of the irreversible processes thermodynamics. This ensures consistency with respect to the well known physics principles (conservation and evolution). The steel reinforcement bars and the CFRP bars are modelled using classical elasto-plastic constitutive laws with an isotropic hardening. The steel/concrete interface is developed in such a way that it may include corrosion. The numerical results are very close to the experimental measurements. Based on that finite element model, the influence of local degradation due to uniform corrosion is then studied. Two effects are considered for this purpose: steel cross section reductions and bond strength variations at the steel/concrete interface. Although these latter results remain informative due to the lack of documented data regarding the corrosion content in the bridge, they allow corroborating experimental measurements published in the literature.