The Influence of Pile Shape on Lateral Load Resistance

The lateral resistance of pile foundations has typically been based on the resistance of round piles even though other pile types are used. Because of a lack of data, a certain level of uncertainty exists when designing pile foundations other than round ones for lateral loading. Theoretical analyses have suggested that square piles will have more lateral resistance because of the increased side shear, but few direct field test results have been available to substantiate this idea. To provide basic comparative performance data, full-scale lateral load tests involving pile shapes such as round, square, and H have been performed to understand the influence of soil-pile interaction on lateral load resistance. The results of the full-scale lateral load tests show higher soil resistance from the H and square piles after accounting for differences in moment of inertia for the different pile shapes. The higher soil resistance can generally be accounted for by using a p-multiplier approach with a value of approximately 1.2−1.25 for square or 1.2−1.35 for H piles relative to the round piles.