Helical Pile Torque-to-Capacity
Ultimate axial capacity from torque × Kt and allowable from factor of safety.
Example
You enter
- Shaft type 1.5_inch_solid
- Installation torque (ft·lb) 5000
- Factor of safety 2
You get
- Torque-to-capacity factor Kt 10
- Ultimate axial capacity 50000
- Allowable capacity 25000 lb
Details, formula, and sources
Engineer of record governs.
Ultimate axial capacity = Kt × installation_torque (lb-ft). Allowable = ultimate / factor_of_safety. Kt by shaft type (engineering-practice values): 1.5 in solid 10, 1.75 in solid 9, 2.875 in pipe 7, 3.5 in pipe 5.
ICC-ES Acceptance Criteria AC358 (helical foundation systems) by name; manufacturer technical bulletins (CHANCE, Magnum, Ram Jack, AB Chance) by name.
ICC-ES AC358 free at icc-es.org. Manufacturer Kt values free in each manufacturer's published evaluation report.
Estimate. Engineer of record governs the design and acceptance. Verify against the project structural drawings and the manufacturer's published capacity / chart.
Field names used by the API: shaft, torque_ft_lb, factor_of_safety, Kt, ultimate_lb, allowable_lb
- Kt table data/construction/helical-pile-kt.json keyed to shaft typemanufacturer technical bulletins
- Default factor of safety 2.0 unless user supplies (engineering-practice default for axial helical piers)ICC-ES AC358 typical