Bridge Assessment and Maintenance based on Finite Element Structural Models and Field Measurements

Rapport, 2008

Maintenance, upgrading, repair and replacement of existing bridges lead to high cost and considerable disruption of traffic. In current practice, condition assessment and the evaluation of existing bridges are mainly based on visual inspection. Since this practice can only disclose faults limited to the surface of the structure, conclusions concerning the underlying structural health are difficult, if not impossible to derive. For bridge evaluations through finite element (FE) analysis a sound numerical model is needed to guarantee the reliability and safety of existing structures. However, in a FE model, used for the design of structural systems, uncertain parameters, such as support conditions and interactions between structural members can have a significant effect on the results. In existing structures, deterioration, damaging events and incomplete blueprints lead to less certain assumptions. To determine the residual load-carrying capacity and the need for strengthening, repair or replacement, a good approximation of the real behaviour of the structure is required. In this report a strategy for improved bridge management by means of advanced structural modelling in combination with on-site measurements is presented. Important aspects of finite element modelling, field testing and monitoring, and FE model updating are presented. Through FE model updating, on-site measurements are combined with an initial FE model to obtain new information about the structural behaviour. This make it possible to benefit from the on-site measurements in an optimal way. It leads to a more accurate FE model and allows determining uncertain structural parameters which can not be measured directly. The study was financed by the Swedish road Administration (Vägverket) and the Swedish railway Administration (Banverket)