Parametric Analysis of the Long-Term Response of a Semi-Integral Bridge Abutment under Cyclic Thermal Movements

Abstract

This paper presents the results of a parametric analysis conducted to assess relevant aspects of the long-term cyclic response of the backfill-abutment system of a semi-integral bridge located in Texas. A two-dimensional finite-element model was developed using the software Plaxis 2D version 2016 to analyze the influence of the completion season of the bridge construction, the stiffness of the bridge foundation, and the lateral displacement amplitude of the bridge abutment on the development of lateral earth pressures on the abutment and settlements on the backfill surface. The analysis was performed by considering the bridge subjected to annual temperature variations over a 50-year period. The outcome of the present investigation indicated a clear influence of the completion season of the bridge construction in the lateral earth pressures in the initial cycles, but the effect vanished in the long term. The completion season of bridge construction affected the settlements throughout the entire 50-year period. Completing the bridge construction in the summer season led to the largest settlements compared with other seasons, while winter was found to be the best period to complete the construction to prevent settlements. Increasing the bridge foundation stiffness reduced both pressures and settlements only slightly. Lower displacement amplitudes caused earth pressures to decrease with the cycles, while higher displacement amplitudes led to an increase of pressures in the initial cycles, followed by a tendency of stabilization in the long term. Conversely, all investigated amplitudes resulted in a continuous increase of settlements with the cycles. Lateral earth pressures continuously increased with increasing amplitude, while settlements escalated at a high rate under small amplitudes and tended to stabilize under large amplitudes. Soil shearing prevailed over soil densification under low amplitudes, while a balance between both shearing and densification was reached under high amplitudes.