Sustainable structural design considers all actions and decisions pertaining to the economic, social and environmental impacts throughout the service life of a structure. For bridges, life-cycle analysis (LCA) includes an inspection and maintenance scenario for bridge components. The assessment of the average service life for each component is generally based on the experience of experts so that the applied measures and actions maintain the whole bridge in a good condition. However, this approach is limited. Firstly, defining a standard framework for maintenance does not take all uncertainties (epistemic and random) into account in terms of the degradation of different bridge components in varying types of environment. Secondly, some degradation processes accelerate or decelerate over time, so kinetic modelling is needed. Thirdly, it is not flexible enough to be included in an optimization process where different maintenance actions and intervals are sought (e.g. minimizing economic, environmental and societal impacts, maximizing accessibility and service level of a structure, etc.) while satisfying quality constraints. The approach proposed in this paper intends to resolve these three issues and is illustrated through the design of steel-concrete composite bridges.