Behavior of concrete integral abutment bridges

The behavior of concrete integral abutment (IA) bridges was investigated through a field experiment and a numerical parametric study. The field investigation focused on an IA bridge, Bridge #55555, in Rochester, MN, which was monitored from November 1996 to February 2004. Over 150 instruments were installed during bridge construction to measure abutment movement, abutment rotation, abutment pile strains, earth pressure, pier pile strains, prestressed girder strains, concrete deck strains, thermal gradients, and weather. The collected data over the past seven years was analyzed to understand the behavior of Bridge #55555 due to the effects of temperature, creep, and shrinkage.; A larger temperature range was observed from the measured data than given in the AASHTO LRFD Specification (2002). A steadily increasing tendency of average pile curvatures was observed from the measured data. Possible reasons were investigated through a time-dependent study using a computer program P-Beam. The tendency may be attributed to the high relative humidity at the bridge site extending the creep and shrinkage period and the thermal-induced passive backfill soil pressure which occurred in each summer that might have increased the creep rate of the girder concrete.; A 3D finite-element model of the test bridge was developed and calibrated using data collected from the truck tests and the data from the seasonal and daily temperature changes. A parametric study was conducted to extend the results of the test bridge to other integral abutment bridges with different design variables including pile foundations (type, size and orientation; depth of fixity; type of surrounding soil), fixity of the connection between the abutment pile cap and abutment diaphragm, bridge span and length, skew angle, type and length of wing walls, and predrilled holes Several design recommendations were made regarding the temperature range, depth of predrilled holes, pile analysis method, hinged connection between the abutment pile cap and abutment diaphragm, low-cycle fatigue of H-piles and the applications of simplified design approaches for concrete integral abutment bridges.