Evaluation of Applicability of Typical Column Design Equations to Steel H-Piles Supporting Integral Abutments

The use of integral abutment bridges with abutments supported on steel H-piles has become common practice in a number of states. These H-piles are subjected to various combinations of axial load and bending moment as the bridge undergoes temperature change. One commonly used approach to the design of these H-piles is, first, to perform an analysis to estimate the distance between inflection points on a pile and, second, to apply the AASHTO or AISC column design equations to the design of the pile. This approach neglects any lateral support provided by the soil between inflection points.Tests were performed to determine the ability of piles to support combinations of axial load and bending moment that fell outside the limits of interaction diagrams based on AASHTO and AISC column design equations. Combinations of axial load and moment were measured which correspond to the plastic limit capacity of a pile cross-section with no length effects considered. The test results clearly demonstrated the inapplicability of the AASHTO and AISC column design equations, which consider length effects, to steel H-piles embedded in soil. Combinations of axial load and moment corresponding to the plastic limit capacity of a pile cross-section can more reasonably be used to evaluate the capacity of a pile.