Open Source Helical Piers Design Guide: Difference between revisions
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*Shaft | *Shaft | ||
=Shaft First Principle Calculations= | =Shaft First Principle Shaft Calculations= | ||
Take the area of steel in the support, and calculate compressive strength to gain a first principle idea of the performance capacity of steel posts. | |||
*'''2-7/8"''': Steel shaft at 2-7/8" diameter and .217 wall has about 1.8 sq in of area according to [[Area Calculator]]. J55 alloy at 55ksi means that ultimate compressive load with 0 margin of safety (see [[Factor of Safety]]) is about 100k lb. | *'''2-7/8"''': Steel shaft at 2-7/8" diameter and .217 wall has about 1.8 sq in of area according to [[Area Calculator]]. J55 alloy at 55ksi means that ultimate compressive load with 0 margin of safety (see [[Factor of Safety]]) is about 100k lb. | ||
*'''2-3/8"''': Steel shaft at 2-3/8" diameter and .156 wall has about 1.1 sq in of area according to [[Area Calculator]]. J55 alloy at 55ksi means that ultimate compressive load is 60 klb. | *'''2-3/8"''': Steel shaft at 2-3/8" diameter and .156 wall has about 1.1 sq in of area according to [[Area Calculator]]. J55 alloy at 55ksi means that ultimate compressive load is 60 klb. | ||
*Safety factor of 4-6 [https://www.engineeringtoolbox.com/factors-safety-fos-d_1624.html] - 10-15 klb allowed load. | *Safety factor of 4-6 [https://www.engineeringtoolbox.com/factors-safety-fos-d_1624.html] - 10-15 klb allowed load. | ||
*This is consistent with the 11,000 lb holding strength of p2 posts - such as | |||
=Flight Spacing= | |||
From [https://www.alphafoundations.com/commercial-foundation-contractor/helical-pile-system.html] | |||
''Helical piles are designed such that most of the axial capacity of the pile is generated through bearing of the helix blades against the soil. The helix blades are typically spaced three diameters apart along the pile shaft to prevent one blade from contributing significant stress to the bearing soil of the adjacent blade. Significant stress influence is limited to a 'bulb' of soil within about two helix diameters from the bearing surface in the axial direction and one helix diameter from the center of the pile shaft in the lateral direction. Each helix blade therefore acts independently in bearing along the pile shaft. | |||
=Links= | =Links= | ||
*[[Open Source Helical Piers]] | *[[Open Source Helical Piers]] | ||
Revision as of 17:28, 19 September 2020
Composition
- Connector Fitting and pin
- Flighting
- Shaft
Shaft First Principle Shaft Calculations
Take the area of steel in the support, and calculate compressive strength to gain a first principle idea of the performance capacity of steel posts.
- 2-7/8": Steel shaft at 2-7/8" diameter and .217 wall has about 1.8 sq in of area according to Area Calculator. J55 alloy at 55ksi means that ultimate compressive load with 0 margin of safety (see Factor of Safety) is about 100k lb.
- 2-3/8": Steel shaft at 2-3/8" diameter and .156 wall has about 1.1 sq in of area according to Area Calculator. J55 alloy at 55ksi means that ultimate compressive load is 60 klb.
- Safety factor of 4-6 [1] - 10-15 klb allowed load.
- This is consistent with the 11,000 lb holding strength of p2 posts - such as
Flight Spacing
From [2]
Helical piles are designed such that most of the axial capacity of the pile is generated through bearing of the helix blades against the soil. The helix blades are typically spaced three diameters apart along the pile shaft to prevent one blade from contributing significant stress to the bearing soil of the adjacent blade. Significant stress influence is limited to a 'bulb' of soil within about two helix diameters from the bearing surface in the axial direction and one helix diameter from the center of the pile shaft in the lateral direction. Each helix blade therefore acts independently in bearing along the pile shaft.