Round VS. Square

Hollow round shaft helical piles are particularly suited to compression loading applications and offer the following advantages over comparably sized square shaft piles.

1.) Round shaft helical piles, excluding those with upset couplers, generally have more rigid coupling connections. Square shaft helical piles typically have a socket and pin coupling which increases variances from straightness, introduces eccentricity to the system, and increases  bucking potential. Square shaft piles may be considered for light concentric compression load applications and in soil profiles that off sufficient lateral support for higher loads.

2.) The load path for round shaft piles in compression is then directly through the shafts without having to pass through the welds or bolts at each coupling. Shaft to shaft contact is more difficult to achieve within forged, upset couplers. For square shaft piles, both compression and tension loads may then be transferred though the signal coupling bolt in double shear.

3.) The area of steel for a round shaft is located outward from the centroid, thereby proving a greater structural section modulus and higher moment of inertia. In layment's terms, a round shaft pile is more resistant to bending. This is an important consideration for piles with unsupported lengths, piles penetrating loose of soft, or for piles that are eccentrically loaded such as in a retrofit application.

4.)Round shaft typically has a higher installation torque rating then a comparably-sized square shaft. For certain product comparisons, this results in higher pile capacities.

5.) Round shaft offers a higher lateral resistance with more shaft area exposed to the surrounding soil. If necessary, hollow round shafts can also be grout-filled to further improve the pile stiffness.