Numerical analysis of a semi-integral bridge abutment undergoing cycles of induced lateral displacements
Semi-integral bridge, Bridge abutment, Cyclic displacement, Numerical analysis, Soil-structure interaction.
Semi-integral abutment bridges (SIAB) are constructed without thermal
expansion joints and the superstructure-abutment system is not integrally
connected to the substructure. In view of the peculiar characteristics of a SIAB,
the abutment’s backwall undergoes combined movements of translation and
rotation due to expansion and contraction of the superstructure caused by
temperature variations. Such behavior favors the increase of stresses and
strains in the soil close to the abutment’s backwall, which is associated to the
cyclic lateral displacement of the superstructure. The purpose of the present
investigation is to assess the effect of cycles of lateral displacements induced
by temperature variations on stresses and strains of the soil behind the
abutment’s backwall of a SIAB located in the State of Texas, USA. A finite
element (FE) model is being developed and validated against field data
collected from the SIAB. Field data were obtained from pressure cells installed
against the abutment’s backwall, and from temperature sensors positioned
under the bridge superstructure. The stress-strain behavior of the soil was
represented by a hyperbolic constitutive model and the effects of expansion and
contraction of the bridge superstructure were given by prescribed horizontal
displacements. Prescribed lateral displacements were estimated from the
temperature variation measured by the temperature sensors. Predictions with
the elaborated numerical model were found to produce a good match with the
field data so far. After being fully validated, the numerical model will be used to
perform sensitivity analysis involving the number of cycles of prescribed
displacements, the displacement amplitude, the backfill stiffness, and
foundation characteristics. This investigation is expected to provide insight into
the complex soil-abutment interaction mechanisms developed in a SIAB under
cyclic lateral displacements.