Predicting seismic performance of locally corroded steel box-section piers

This paper aims to propose a simplified method for predicting ultimate strength and ductility behavior of locally corroded steel box-section bridge piers. Firstly, the accuracy of the proposed 3-D elastoplastic finite element model for the steel piers subjected to a constant vertical load and cyclic lateral loading is verified by comparing the analytical results with test results. Then, a series of parametric study is carried out to investigate the effect of corrosion height ratio and corrosion thickness ratio of steel plates on the ultimate strength and ductility behavior of these piers. Finally, by establishing 2-D beam-column element models and comparing the calculation results with those of the 3-D models, correction coefficients for the ductility ratio and ultimate strength of 2-D beam-column element model under local corrosion are proposed. The research results indicate that there exists a most unfavorable corrosion height which makes the ductility ratio of steel piers the smallest. The ultimate strength of the steel piers will not have a distinct degradation when the corrosion height becomes larger than 0.5Ld. The correction coefficient formula for ductility ratio with respect to different aspect ratio of steel piers, and the linear relationship between correction strength coefficient and the corrosion thickness ratio are proposed. Correction coefficients for 2-D beam-column element model under the most unfavorable corrosion height are proven to have a rational accuracy, which provides a fast and simplified method to evaluate the ultimate strength and ductility behavior of such steel piers under local corrosion.