Load Testing and Modeling of Two Integral Abutment Bridges in Vermont, US

Abstract

Load testing of two instrumented single-span integral abutment bridges (IABs) in Vermont, US, was conducted using loaded multiple tandem dump trucks. Data was used to validate finite element (FE) models of each structure. Field data and FE model results were compared to gain an understanding of the distribution of live load on completed integral bridges and resulting stresses and deformations in structural components. The superstructure of the two bridges consists of a concrete deck supported on steel I-girders that are cast integrally into concrete abutments at the bridge ends. Abutments are supported on H-piles oriented with their weak axis resisting deformations in the direction of bridge alignment. The spans of the two bridges are 43 and 37 m, with girders connected to the abutments perpendicularly and with a skew angle of 15°. Correlation of measured data, such as girder strains, pile strains and deflections, abutment displacements, and backfill pressures, with FE model values are presented. Important considerations in the interpretation of field data are presented, including evaluations of the degree of composite action in girders, effects of thermal fluctuations over the course of testing and challenges faced when using field data directly to compute live load distribution factors.