Analysis of FRP-Wrapped Concrete Piles in Integral Abutment Bridges Subjected to Axial and Cyclic Lateral Loads

Abstract

ABSTRACT The long-term maintenance problems associated with expansion joints, which are used to accommodate bridge movements in conventional bridges, have been the primary motivation for the use of integral abutment (jointless) bridges. These bridges rely on the interaction between the structure and the surrounding soil to accommodate bridge movements without the use of any expansion joints on the bridge superstructure. As the bridge superstructure expands and contracts due to seasonal thermal and other strains, relatively large forces can develop in the pile near the pile-cap interface. These reversible moment and shear forces can lead to localized damage near the top of the pile. Steel piles are the most commonly used type of piles in integral abutment bridges. However, concrete piles are preferred in some regions of the United State as well as other countries due to economic factors and soil conditions. Concrete piles are susceptible to cracking and spalling at the pile/pile cap interface and that has limited their use in integral abutment bridges. This study was aimed at determining the behavior and performance parameters in integral abutment bridges that are supported by concrete piles and evaluating the effect of carbon fiber reinforced polymer composites in mitigating the expected localized damage in these piles. To achieve these objectives, a comprehensive review of literature was first conducted. Two sets of analytical models were prepared using the ABAQUS finite element program to analyze prestressed concrete piles in integral abutment bridges with or without localized FRP reinforcement at the interface between the pile and the pile cap. The effectiveness and accuracy of the finite element models were verified using three sets of available experimental data. Also, a comprehensive parametric study was conducted to understand and compare the influence of various parameters on the behavior of the bridge and the pile. Empirical equations were developed to estimate the pile displacement and the abutment rotation based on the span length, the height of the abutment and the girder displacement. Results indicate that the use of carbon fiber reinforced polymer composite wraps can substantially reduce damage at the pile-abutment interface. However, the magnitude of shear and movement forces imposed by the pile on the abutment and bridge superstructure increase as a result of the reduction in damage. Estimates of these forces for various bridge span lengths and soil conditions are provided. A set of design recommendations are provided for the application of concrete piles in integral abutment bridges using CFRP composites in retrofit cases or in new bridges construction.