Nine-Year Field-Monitoring Data from an Integral-Abutment Bridge

Many field studies of integral abutment bridges have focussed on construction and short-term behaviour, while the data on long-term performance are not abundant. In this paper, long-term field monitoring data from an instrumented integral abutment bridge in Fredericton, NB are presented. The primary objective is to add to the limited database of long-term monitoring so that the information might be used to calibrate numerical methods predicting long-term performance over the design life of a bridge. In this paper, data of abutment movements and earth pressures on the abutments over a 9-year monitoring period are presented. Field data indicate that the primary mode of movement for one abutment is translation and a combination of rotation and translation for the other abutment. Data also indicate that the abutments are tilting in opposite directions to one another, resulting in torsion of the bridge superstructure. Finally, of particular interest, is the concern of earth pressure ratcheting. Data do not conclusively show an increase in passive earth pressures behind the abutment over the 9-year monitoring period.