The durability and resilience of concrete bridges are significantly affected by degradation processes such as carbonation, chloride ingress, elevated temperatures, rebar corrosion, and concrete cracking, all of which compromise structural integrity. To address these challenges, current research has shifted towards multi-physics, multi-scale prediction theory that investigates the coupled effects of environmental, material, and mechanical factors, including temperature, humidity, chemical reactions, and mechanical stress. Key scientific challenges include understanding crack initiation and propagation, accurately modeling the coupling of multi-field processes, and linking mesoscale mechanisms to the behavior of large-scale structures. This presentation introduces a multi-physics field coupling theory at the mesoscale to address degradation mechanisms such as carbonation, chloride penetration, rebar corrosion, cracking, and fire-induced damage. The model integrates chemical, electrochemical, thermal, and mechanical processes, providing in-depth insights into the interactions between these factors and laying a foundation for informed bridge maintenance strategies.