Soil-Structure Interactions in a Skewed Integral Abutment Bridge

Abstract

Integral Abutment Bridges (IABs) are jointless bridges and are increasingly being used to eliminate undesirable effects of bridge joints on the long-term performance of bridges. However, the behavior of abutments in an IAB is poorly understood. This paper describes an effort to understand the complex soil-structure interactions occurring in IABs through field performance and numerical modeling. Data from the field monitoring of an existing 64.0 m long, three span IAB with a 10° skew in Oklahoma are presented. Results are presented for a 40-month period of monitoring covering a bridge temperature change of 95 °F. Field measured bridge temperatures agree with the temperature range specified in American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. Earth pressures on the abutments induced by thermal loading of bridge are consistent with temperature changes and fairly significant amount of abutment back pressures have been recorded during summer. Recorded abutment pile strains show piles are experiencing bending moments beyond the yield bending moment at shallow depths for seasonal temperature variations. Numerical modeling of this IAB confirms abutment piles have yielded at shallow depths, however, computed bending moments are greater than field measured values. Several factors are attributed to the difference between field measured and computed bending moment values.