Transmission And Substation Foundations - Technical Design Manual

SECTION 7: DESIGN EXAMPLES

Design Example 3

(4) SS175 PULLDOWN PILES

SS175 PULLDOWN PILE BATTERED 10° FROM CENTER (TYP)

TYP. 10° PILE W/CAP

6” GROUT COLUMN WITH 6” NOMINAL SCHEDULE 40 CASING

SS175 SHAFT

5.1

*PILE CAP DESIGNED BY OTHER

*DRAWING FOR CONCEPTUAL PROPOSED ONLY.

Figure 7 -14: Pile Layout

Recommendation: 1. Install a SS175 Helical Pulldown Micropile a. 6” Grout Column b. Case first 12 ft with minimum 6” Nominal Schedule 40 `

iii. Shear

1. Transverse: 9.5kip 2. Longitudinal 4kip

iv. Moment:

` pipe per ASTM A500 GRD B c. Helix Configuration: 10/12/14/14

1. Longitudinal: 150kip ft. c. Piles are installed at ground level d. Torque to Capacity Ratio: 10:1 d. Head Condition: Fixed e. Axial FS: 2.0 f. Amount of Lateral deflection acceptable at working loads: 0.2 3. Notes i. May reach installation torque before reaching minimum embedment. Adhere to minimum embedmentrequirements ii. Ensure final torque is greater than required installation torque at given depth iii. Maximum torque for SS175 is 10,500 ft-lbs. Do not Overtorque! (Torque capacities can be found in the Drawings and Ratings section)

d. Installation torque and length per attached installation ` ` torque vs required pile length plot Figure 7-13 e. Locate piles per attached Pile Layout (Figure 7-14) f. Estimated Embedment: 40 ft g. Minimum embedment: 27 ft (16+11) 2. Assumptions a. Boring is representative of the site 1. Water table depth: 0 ft. b. Loads given:

i. 100kip Comp ii. 80kip Tension

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