Estimating Operating Load Conditions on Reinforced Concrete Highway Bridges with b-value Analysis from Acoustic Emission Monitoring

Transportation agencies commonly have conventionally steel reinforced concrete deck girder (RCDG) bridges in their inventory that were built in the mid-twentieth century. These bridges have been in service beyond their intended design lives and tools are needed to permit freight mobility and maintain operational safety. The practical applicability of AE monitoring techniques were investigated to help estimate the condition of diagonally cracked RCDG bridges. Experiments on two full-scale girder specimens representative of Oregon’s RCDG bridges were built and tested under realistic service conditions. Overloading conditions were imposed to increase the level of deterioration. It was found that characterizing the current health condition of a monitored bridge component or element based on short term in service loading is difficult and the proximity of a potential bridge failure not easily predictable until it is impending. However, it was observed that the current operating load level of a bridge component can be estimated using a newly proposed method called minimum b-value analysis. The influence of factors that can affect b-value estimations such as stage of deterioration or external sources was studied and is introduced. The experiment as well as data from the two laboratory specimens are presented and interpreted.