Transmission And Substation Foundations - Technical Design Manual (TD06088E)

With the final ultimate capacity known, the torque required for installation can be calculated. Equation 7-4 shows the equation for calculating installation torque.

Installation Torque (ft-lbs)=required Capacity(kip)*1000/k t

Equation 7-4

• k t =7 for RS3500 • Required Capacity is 90 kip • Installation torque: 1000*90/7=12,900 ft-lbs Recommendation: 1. Install 4-RS3500.300 helical piles a. Helix Configuration: 10/12/14/14/14/14

b. Installation Torque: 12,900 ft-lbs c. Estimated Embedment: 50 ft. d. Minimum embedment: 14 ft.

2. Assumptions a. Boring B-1 is representative of the site 1. Water table: 10 ft. b. Loads given: a. 130kip Comp b. 100kip Tension c. Shear: 1. Transverse 10kip 2. Longitudinal 10kip c. Piles are installed at ground level d. Pile Revea: 1 ft. e. Torque to Capacity Ratio: 7:1 f. Fixed Head Condition g. Axial FS: 2.0 i. Amount of Lateral deflection acceptable at working loads: 0.7" 3. Notes a. May reach installation torque before reaching minimum embedment. Adhere to minimum embedment b. Maximum torque for RS3500.300 is 13,000 ft-lbs. Do not Overtorque!

DESIGN EXAMPLES

Page 7-15 | Hubbell Power Systems, Inc. | All Rights Reserved | Copyright © 2017