field investigation of service performance of concrete bridges exposed to tropical marine environment

A preliminary field inspection by the drr (department of rural roads, thailand) revealed deficient significantly deteriorated highway bridges, damaged by exposure to the tropical marine environment along the southern coastline of thailand. to assess the causes of deterioration, the damages, and the residual structural performance, a long-term research program was launched by the drr to resolve and review deterioration from corrosion effects. an initial effort within this program was to investigate and evaluate by field testing 19 concrete bridges in poor or critical condition. it was observed that the concrete strength and covering depth in the current design specifications were insufficient to sustain the targeted 50-year service life. based on these field data, a simplified model was developed to predict the residual capacities of bridge structural members. the model for concrete bridge beams predicts that the design service life is reduced by 25% by this specific marine environmental exposure. the structural performance of columns and piles in axial bending decreases significantly, which seriously impair the overall bridge structure.