The behavior of concrete integral abutment bridges was investigated through a field experiment and a numerical parametric study. The field investigation focused on Bridge #55555 in Rochester, Minnesota, which was monitored from November 1996 to February 2004. Over 150 instruments were installed during construction of the bridge to measure abutment horizontal movement, abutment rotation, abutment pile strains, earth pressure, pier pile strains, prestressed girder strains, concrete deck strains, thermal gradients, and weather. The collected data were used to understand the behavior of Bridge #55555 due to the effects of temperature, creep and shrinkage. Two live load tests were conducted in 1997 and 1999, to examine the behavior of the bridge under live load. The overall performance of the integral abutment bridge was good. Bridge shortening was observed from the readings of different sensors. A steadily increasing tendency of average pile curvatures was observed from the measured data. Possible reasons were investigated through a time-dependent numerical analysis. A 3D finite element model of the test bridge was developed which took into account soil-structure interaction. The model was calibrated using data collected from the truck tests and the data from the seasonal and daily temperature variations. A parametric study was conducted to extend the results of the test bridge to other integral abutment bridges with different design variables including pile foundation type, bridge span and length, and orientation and length of wingwalls. Several design recommendations are made regarding the temperature range, use of predrilled holes around the piles, pile analysis method, and the applications of simplified design approaches for concrete integral abutment bridges.
