Numerical analysis of a semi-integral bridge abutment undergoing cyclic lateral displacements

• Autor(a) principal: Silva, Pedro Henrique dos Santos
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/30872
• topic: Semi-integral bridge; Bridge abutment; Soil-structure interaction; Cyclic loading; Finite element method

Integral abutment bridges (IABs) and semi-integral abutment bridges (SIABs) are structural systems built without thermal expansion joints at the abutments. In view of this peculiar characteristic, the abutment undergoes combined movements of translation and rotation due to the expansion and contraction of the superstructure caused by temperature variations. Such behavior favors the increase of lateral earth pressures on the abutment and vertical displacements of the backfill surface, due to a complex soil-structure interaction mechanism associated with the cyclic lateral displacements of the abutment. The purpose of the present investigation is to assess the effects of cyclic lateral displacements on the response of the backfill-abutment system of a SIAB. A finite element model was developed and validated based on field data from an instrumented SIAB located in the State of Texas, USA. Field data were obtained from pressure cells installed against the abutment, and from temperature sensors positioned under the bridge superstructure. The soil stress-strain behavior was represented by a hyperbolic constitutive model, and the effects of expansion and contraction of the superstructure were simulated by prescribed horizontal displacements estimated from temperature variations measured by the temperature sensors. Predictions with the proposed numerical model were found to produce a good match with field data. After the validation phase, numerical simulations were performed to predict the daily and annual responses of the backfill-abutment system, as well as to analyze the influence of the completion season of the bridge construction, the pile foundation stiffness, and the lateral displacement amplitude on the response of the system. It was found that lateral earth pressures on the abutment and vertical displacements of the backfill surface increased with cycles. Lateral earth pressures presented a nonlinear distribution along the abutment height. The backfill experienced settlements near the abutment and heave at a certain distance from the abutment. The largest settlements occurred near the backfill-abutment interface and decreased with increasing distance from the abutment. While vertical displacements were not found to stabilize, earth pressures tended to reach a steady state after a few cycles. The completion season of the bridge construction influenced the vertical displacements but not the lateral earth pressures. Lateral earth pressures and vertical displacements were not affected by the pile foundation stiffness. However, the lateral displacement amplitude influenced both lateral earth pressures and vertical displacements.