Application of the 3D chemo-hygro-thermo mechanical model on existing bridges exposed to chlorides and mechanical damages

Bridge engineering world practice has showed that implicit method of service life prediction, relying on sufficient quality and depth of concrete cover, do not guarantee a 100- year structure lifetime without major, complex and expensive repair works. Bridges exposed to harsh combination of mechanical (static, dynamic, cyclic loading) and environmental (sea salts, de-icing agencies, freeze - thawing cycles, etc.) actions are particularly vulnerable. Two such case studies: Krk Bridge and Maslenica Bridge located in aggressive maritime environment will be analysed in the paper including in-service performance and comparison between measured values on bridges and numerical results obtained by two numerical models for service life prediction: the 3D chemo-hygro-thermo mechanical (3D CHTM) model implemented into the finite element code MASA and the Life-365 model. Both models are capable to realistically predict chloride content in concrete after long-term exposure to seawater. However, the 3D CHTM model, which considers cracks and damage in concrete, anticipates the beginning of steel reinforcement depassivation much more precisely than the other model which doesn't take concrete damage and cracks into account.