Transmission And Substation Foundations - Technical Design Manual (TD06088E)

The Factor of Safety for this compression pile is R uc / DL = 50.7 / 22.7 = 2.23 > 2 (OK) Use three SS175 helical piles per tower base. The three helical piles must be captured in a “pile cap.” This may be a reinforced concrete cap, the design of which is beyond the scope of this design example. The design of this concrete pile cap is left to the structural engineer.

T = (DL x FS) / K t

Equation 7-3

= (22,700 x 2.0) / 10 = 4,500 ft-lbs

where: = Empirical torque factor = 10 (default value for Type SS175 series) T = 4,500 ft-lbs is less than the rated torque (10,500 ft-lbs) of the type SS175 series. (OK). K t

DESIGN EXAMPLES

Sample Boring Log Figure 7-2

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