Loading Test of RC Beam Bridge Built 80 Years Ago in Japanese Coastal Area

Many concrete structures have to be now repaired or replaced due to salt attack in Japanese coastal area. However, their residual strength is not well considered in practice. This is because only few studies have so far been made on the residual strength of deteriorated concrete structures. Objective of this research is to study about the load carrying capacity and the failure behaviour of corroded real RC bridge. Firstly, we sawed the reinforced concrete bridge to take out beam specimens. The bridge was seriously corroded because it was built about 80 years ago in Japanese coastal area. Two beam specimens were carried into experimental room and loaded until failure. Load carrying capacities of these two specimens were quite different. Maximum load of the relatively sound beam was about 96% of the estimated capacity of non damaged beam. On the other hand, the relatively deteriorated beam had only 48% of load carrying capacity. To examine the cause of the reduction in loading strength, layout of reinforcement and corrosion rate of longitudinal bars in concrete were carefully inspected. In the inspection, several lap splices were found in tensile area while the difference in corrosion rate is much smaller than the difference in strength. Thus, the cause of reduction in loading capacity is considered as bonding failure at lap splice. Finite Element analysis was conducted to simulate test results. It was confirmed that FE analysis can estimate the structural behaviour of test beams if the bond strength of each lap splice is obtained first.