Structural performance of corroded bridge column and drilled shaft connections with non-contact lap splices

Abstract

The connections between non-circular bridge columns and the supporting circular mono-drilled shafts often require non-contact lap splices. It is found from previous laboratory tests that in addition to flexural, shear and split tensile cracks, a major opening occurs at the interface between the bridge column and drilled shaft, resulting in a serious issue of corrosion. Based on the experimental results, a high-fidelity finite element model of a bridge column-drilled shaft connection with non-contact lap splices in Grand Parkway, Texas, is established with consideration of the corrosion effect. Based on existing research, the corrosion density (icorr) of reinforcing bars is around 5 µA/cm2 for concrete with high humidity content carbonated or containing chlorides and 10 µA/cm2 for concrete highly contaminated with chlorides. The pit corrosion model is adopted to simulate the strength degradation and area reduction of the dowel bars and column bars. Based on the finite element simulation results, the failure mode and the load-displacement curves are obtained. The influence of key factors, such as the spacing between dowel bars and column longitudinal bars, the corrosion density, and the bridge age, are investigated. The finite element simulation results show that in the current design with a maximum of 8-inch spacing between dowel bars and longitudinal column bars, the lateral capacity of the bridge column will be reduced by 16% and 41% at the corrosion density of 5 µA/cm2 and 10 µA/cm2 respectively in 20 years. The lateral displacement at service load increased by 14% and 151% respectively at the corrosion rate of 5 µA/cm2 and 10 µA/cm2 respectively in 20 years.