Parametric Study for Understanding the Behavior of Integral Abutment Bridges: Fid-Bau Portal

Parametric Study for Understanding the Behavior of Integral Abutment Bridges

Kirupakaran, Karrthik / Muraleetharan, Kanthasamy K.

Integral abutment bridges (IABs) are being used widely across U.S. due to the elimination of joints and the superior long-term performance of these bridges. However, the performance of IABs is dependent on the soil-structure interactions that are not well understood. This paper describes an effort to understand the complex soil-structure interactions occurring in IABs through a parametric study conducted to extend the results of a field instrumentation study on an IAB in Oklahoma to other IABs with different design variables. Abutment pile type, size and orientation, bridge length, girder depth, soil type, pre-drilled holes around abutment piles, and bridge skew angle were the variables considered in the study. Validated simulation tools GROUP and TeraDysac were used for the numerical simulations. According to the simulation results, in order to accommodate thermal movement in IABs and to reduce bending moments in abutment piles, a smaller H-pile section should be placed in weak axis bending and in pre-drilled holes with low stiffness material, especially at shallow depths. Abutment piles for IABs should be checked for capacities under combined axial force and bending moments. Longer spans with larger girders will increase the axial load on the abutment piles, and therefore long-span IABs should be designed with caution. For IABs with larger skew angles, abutment piles should be oriented in weak axis bending along the transverse direction. Biaxial bending of abutment piles in skewed IABs increases stresses in the concrete superstructure, thus the structural components for IABs with larger skew angles have to be designed carefully to accommodate the thermally-induced deformations.