ANTAMINA PROJECT

220 kV TRANSMISSION LINES

STEEL GRILLAGE FOUNDATIONSFOR TOWERS 22A1.2T

Revised Approved Date

Report 30-24-20-E - Rev 0

GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

REVISION

REV DESCRIPTION DATE

A0

First IssueApproved

June, 24Set, 18

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

220 kV TRANSMISSION LINES

STEEL GRILLAGE FOUNDATIONSFOR TOWERS 22A1.2T

CONTENT

1.00 PURPOSE

2.00 STANDARDS & REFERENCES

3.00 PROJECT DATA

4.00 CONFIGURATION OF STEEL GRILLAGE

5.00 STRESS CALCULATION

6.00 STEEL ELEMENTS DESIGN

ANNEXCALCULATION OF STEEL GRILLAGEM TOWER 22A1.2T + 0.00CALCULATION OF STEEL GRILLAGEM TOWER 22A1.2T + 6.00CALCULATION OF STEEL GRILLAGEM TOWER 22A1.2T + 9.00

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

220 kV TRANSMISSION LINES

STEEL GRILLAGE FOUNDATIONSFOR TOWERS 22A1.2T

CONTENT

1.00 PURPOSE

The purpose of this document is to verify the steel grillage foundation of the Towers 22A1.2T in Soil type III, which is 3 kg/cm² of compression capacity.

2.00 STANDARDS & REFERENCES

The calculations have been done on the basis of the loads on the foundations, according to the tower calculations provided by the tower designer.

The calculations have as a technical reference the book of R.F. Craig, Soil Mechanics.

3.00 PROJECT DATA

3.01 Soil characteristics

- Allowable compression capacity of soil qad (kg/cm2) = 3- Mass volumetric weight m (kg/cm3) = 1555- Internal friction angle - Uplift angle = 30°

3.02 Service loads

Fd = Compression maximum forceFci = Traction maximum forceFLi = Longitudinal forceFti = Transverse force

where:f = forces from "i" hypothesis to be applied at ground level

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

4.00 CONFIGURATION OF STEEL GRILLAGE

Choose: Thirteen (13) L 60x60x5 and four (4) U 80x45x6

Z1 = 13B1 = 8,48 cm (2 x 6 x sin45= 8.48cm)c = b = 200 cmZ2 = 4b2 = 8 cm

It is defined “liquid area” of steel grillage as area in direct contact with soil m2 according to the formula

where:

Z1 – Total number of “L” profiles used for grillageb1 – profile width cmb – length of “L” profile(cmZ2 – total number of transverse profiles “U” used for grillageb2 – profile width cmc – length of “U” profile cm (in this case b=c=200cm)

The coefficient of liquid area is a relation between surface covered by grillage and liquid area of the project

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

5.00 STRESS CALCULATION

According to "Soil Mechanics - R.F. Craig page 178", horizontal stress:

where

3 = horizontal stress1 = vertical stress (allowable pressure)a, b, g: geometric characteristics of grillageh: foundation depth

a = 1.17mg = 0.415mb = 2m

The horizontal dimensions at top of foundation taking account the influence of frustum angle are

The soil volume influenced by the grillage [m3] is

If the soil weight is PT kgf and the estimated weight for foundation grillage PG

kgf = 280 kg. Then the safety coefficient for anchored soil:

The medium soil pressure is:

and the maximum soil pressure is:

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

where:

max : maximum stress on soil foundation1 : maximum stress on transversal directionL : maximum stress on longitudinal directionC : maximum stress in compression

a) TRANSVERSAL DIRECTION

b) LONGITUDINAL DIRECTION

c) COMPRESSION TERM

6.00 STEEL ELEMENTS DESIGN

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

6.01 Check “L” profiles

L 60x60x5 mm

S = 3,46 cm3

Number of “L” = 13TOTAL S = 44,98cm3

eadm = 0,66 Fy for St52

eadm = 2370 kg/cm2

6.02 Check of “U” profiles

U 80x45x6 mm

A (cm2) = 11Iy(cm4) = 19,4NUMBER OF “U” = 4

TOTAL A (cm2) = 44S (cm3) = 96,4 S: section module

M2 = M3

eadm = 1600 kg/cm2

eadm = 0,66 Fy for St36

Fy = elastic limitFy = 2400 kg/cm2 Normal SteelFy = 3600 kg/cm2 St52 High Resistance

a(cm) = 117

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GRILLAGE FOUNDATIONS FOR TOWERS 22A1.2T30-24-20-E – Rev 0

Lf(cm) = 263,33Lf1 = Lf2 = Lf / 2 (cm) = 132Choose:L70x70x6Area(cm2) = 8,13rz = 1,37

rz: minimum turning radius: slenderness ratio

If Fu: last load in each foot and Fsi : Safety factor for the hypothesis

Fu = 1,15 • F • Fsi

And the effective stress:

The ultimate stress (according to AISC-LRFD) is:

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