Masaki Sakurai

Development of a Cyberspace Simulator Applied to Predicting Environmental Degradation of Concrete Structures

Fuminori Nakamura

This study developed a cyberspace simulator that combines high-fidelity 3D digital reconstruction of real infrastructure with coupled models of environmental loading and mass transport in concrete to predict chloride-induced deterioration. A coastal bridge (Nadachi Bridge, Japan Sea side) was reproduced in a 3D virtual space where users can visualize and manipulate the structure and inspect time-dependent boundary actions. Predicted airborne salt deposition, raindrop impingement and washing, and solar-radiation-driven temperature changes were used as boundary conditions for hourly simulations (Nov. 2001–Oct. 2025) of internal moisture and chloride ion migration. Results showed that environmental actions around the girder can be evaluated spatiotemporally, and that chloride content on the sea-facing side exceeds that on the land-facing side. Near the surface, chloride tended toward a quasi-steady state where salt supply and loss by rainfall were balanced. Numerical experiments that repeated “maximum-salt” years (2005, 2013, 2017) and “minimum-salt” years (2016, 2019, 2024) demonstrated scenario analysis capability: at 50 mm depth, the maximum-salt case produced about 1.4× the chloride amount of the minimum-salt case, and early high-salt exposure increased chloride accumulation at 60–100 mm depth. Overall, the simulator enables integrated prediction and what-if assessment of changing natural environments.