Micropile Design Check

Micropile Design Check Design of Cased Length Variable Value Units Casing Size API N-80 ODcasing 7.00 in. tw-casing 0.453 in. C'casing 0.063 in. Acasing 7.96 in.2 Bar Type solid Bar Size #18 ODbar 2.25 in. IDbar 0.00 in. Abar 4.00 in.2 Agrout (w/ bar) 25.17 in.2 Agrout (w/o bar) 29.17 in.2 Fy-casing 80 ksi Fy-bar 75 ksi Fc-grout 87 ksi f'c 4 ksi Compression Capacity Pc-allowable (w/ bar) 408 kips Pc-allowable (w/o bar) 293 kips Tensile Capacity Pt-allowable (w/ casing) 515 kips Pt-allowable (w/o casing) 165 kips Variable Value Units PG-allowable (w/ bar) 105 kips PG-allowable (w/o bar) 105 kips FSbond 2.00 A' 0.00 in. Db 7.00 in. αbond 125 psi Bond Length Lb 76.4 in. Lb 6.4 ft. Pc-allowable bond zone 165.5 kips Determine Plunge Length Variable Value Units Plunge Length 12 in. FSbond 2.00 -

INPUTS OUTPUT OUTPUT

𝐶′𝑐𝑎𝑠𝑖𝑛𝑔 = sacrificial thickness of casing 𝐴𝑐𝑎𝑠𝑖𝑛𝑔 =

𝜋 (𝑂𝐷 − 2𝐶 ′ )2 −𝐼𝐷2 4

𝐼𝐷 = 𝑂𝐷 − 2𝑡𝑤

Choose hollow or solid Input number only 𝜋 𝑂𝐷 2 − 𝐼𝐷 2 4 𝜋 𝐴𝑔𝑟𝑜𝑢𝑡 (𝑤/ 𝑏𝑎𝑟) = 𝐼𝐷𝑐𝑎𝑠𝑖𝑛𝑔 4

𝐼𝐷 = 𝑂𝐷 − 2𝑡𝑤

𝐴𝑏𝑎𝑟 =

𝐴𝑔𝑟𝑜𝑢𝑡 (𝑤/𝑜 𝑏𝑎𝑟) =

𝜋 𝐼𝐷𝑐𝑎𝑠𝑖𝑛𝑔 4

2

− 𝐴𝑏𝑎𝑟 2

𝑃𝑐−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/ 𝑏𝑎𝑟) = 0.33𝑓′𝑐−𝑔𝑟𝑜𝑢𝑡 × 𝐴𝑔𝑟𝑜𝑢𝑡 + 0.40𝐹𝑦−𝑐𝑎𝑠𝑖𝑛𝑔 𝑃𝑐−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/𝑜 𝑏𝑎𝑟) = 0.33𝑓′𝑐−𝑔𝑟𝑜𝑢𝑡 × 𝐴𝑔𝑟𝑜𝑢𝑡 + 0.40𝐹𝑦−𝑐𝑎𝑠𝑖𝑛𝑔 𝑃𝑡−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/ 𝑐𝑎𝑠𝑖𝑛𝑔) = 0.55𝐹𝑦−𝑐𝑎𝑠𝑖𝑛𝑔 𝐴𝑐𝑎𝑠𝑖𝑛𝑔 + 0.55𝐹𝑦−𝑏𝑎𝑟 𝑃𝑡−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/𝑜 𝑐𝑎𝑠𝑖𝑛𝑔) = 0.55𝐹𝑦−𝑏𝑎𝑟 × 𝐴𝑏𝑎𝑟

𝐴′ = 𝑏𝑜𝑛𝑑 𝑧𝑜𝑛𝑒 𝑎𝑛𝑛𝑢𝑙𝑢𝑠

𝐿𝑏 =

𝑃𝐺−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 × 𝐹𝑆 𝛼𝑏𝑜𝑛𝑑 × 𝜋 × 𝐷𝑏

𝑃𝑐−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 𝑏𝑜𝑛𝑑 𝑧𝑜𝑛𝑒 = 0.33𝑓′𝑐−𝑔𝑟𝑜𝑢𝑡 × 𝐴𝑔𝑟𝑜𝑢𝑡 + 0.40𝐹𝑦−𝑠𝑡𝑒𝑒𝑙

Db

7.00

in.

αbond

125.00 psi Load on Casing Ptransfer-allowable 16.5 kips Initial Buckling Check Esteel 29000 ksi Icasing 50.2 in.4 Lcasing 360 in. EsLIMIT ES

7.0E-02

-

1.0E-01 Critical Buckling Load Pcr IGNORE kips Compression and Bending Buckling fa-casing (w/ bar) 51.3 ksi fa-casing (w/o bar) 36.8 ksi Fa-casing

37.6

ksi

Mmax

0.0

kip∙in.

Icasing

50.2

4

in.

3

Scasing

14.3

fb-casing

0.0

in. ksi

Fb-casing

44.0

ksi

Kcasing

1.0

-

Lcasing

360.0

in.

rcasing

2.51

in.

Esteel

29000

ksi

FSEuler F'e P'e

2.12 Euler Buckling 6.5685

𝑃𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 =

𝜋 𝑂𝐷 4 −𝐼𝐷4 64 𝐿𝑐𝑎𝑠𝑖𝑛𝑔 = length of casing affected by weak soil or voids 1 𝐸𝑆𝐿𝐼𝑀𝐼𝑇 = 4𝐼𝑐𝑎𝑠𝑖𝑛𝑔 𝐸𝑠𝑡𝑒𝑒𝑙 𝜋 2 𝐸𝑠𝑡𝑒𝑒𝑙 𝐼𝑐𝑎𝑠𝑖𝑛𝑔 2 2 𝑃 = + 𝐴𝑐𝑎𝑠𝑖𝑛𝑔 𝐹𝑦−𝑠𝑡𝑒𝑒𝑙 𝑐𝑟 𝐿2𝑐𝑎𝑠𝑖𝑛𝑔 𝐼𝑐𝑎𝑠𝑖𝑛𝑔 =

𝐸𝑆 = lateral reaction modulus of the soil

𝑓𝑎−𝑐𝑎𝑠𝑖𝑛𝑔 (𝑤/ 𝑏𝑎𝑟) = 𝑃𝑐−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/ 𝑏𝑎𝑟) /𝐴𝑐𝑎𝑠𝑖𝑛𝑔 𝑓𝑎−𝑐𝑎𝑠𝑖𝑛𝑔 (𝑤/𝑜 𝑏𝑎𝑟) = 𝑃𝑐−𝑎𝑙𝑙𝑜𝑤𝑎𝑏𝑙𝑒 (𝑤/𝑜 𝑏𝑎𝑟) /𝐴𝑐𝑎𝑠𝑖𝑛𝑔 𝐹𝑎−𝑐𝑎𝑠𝑖𝑛𝑔 = 0.47𝐹𝑦−𝑐𝑎𝑠𝑖𝑛𝑔 𝑀𝑚𝑎𝑥 = maximum bending moment in the micropile 𝜋 𝐼𝑐𝑎𝑠𝑖𝑛𝑔 = 𝑂𝐷 4 −𝐼𝐷4 64 𝐼𝑐𝑎𝑠𝑖𝑛𝑔 𝑆𝑐𝑎𝑠𝑖𝑛𝑔 = (𝑂𝐷/2) 𝑓𝑏−𝑐𝑎𝑠𝑖𝑛𝑔 = 𝑀𝑚𝑎𝑥 /𝑆𝑐𝑎𝑠𝑖𝑛𝑔 𝐹𝑏−𝑐𝑎𝑠𝑖𝑛𝑔 = 0.55𝐹𝑦−𝑐𝑎𝑠𝑖𝑛𝑔 𝑟𝑐𝑎𝑠𝑖𝑛𝑔 =

𝐹′𝑒 =

ksi

52 kips Compression and Bending Check Criteria 1.36 CHECK!

𝛼𝑏𝑜𝑛𝑑 × 𝜋 × 𝐷𝑏 × 𝑃𝑙𝑢𝑛𝑔𝑒 𝐿𝑒𝑛𝑔𝑡𝑕 𝐹𝑆

𝐼𝑐𝑎𝑠𝑖𝑛𝑔 /𝐴𝑐𝑎𝑠𝑖𝑛𝑔

𝜋2𝐸 𝐹𝑆𝐸𝑢𝑙𝑒𝑟 𝐾𝑙/𝑟

2

𝑃′𝑒 = 𝐹′𝑒 × 𝐴𝑐𝑎𝑠𝑖𝑛𝑔 Compression and Bending Check:

𝑓𝑎 𝑓𝑏 + ≤1 𝑓 𝐹𝑎 1 + 𝑎 𝐹𝑏 𝐹′𝑒

Bar Development Length Variable Value Units f'c 4000 psi Bar Size 18 ODbar 2.25 in. Fy-steel 75000 psi ld2 4.45 ft. ld3 3.71 ft. ld min 4.22 ft. Development Length ld 4.45 ft.

𝑐𝑎𝑠𝑖𝑛𝑔 𝐴𝑐𝑎𝑠𝑖𝑛𝑔 𝑐𝑎𝑠𝑖𝑛𝑔

+ 0.40𝐹𝑦−𝑏𝑎𝑟 𝐴𝑏𝑎𝑟

× 𝐴𝑐𝑎𝑠𝑖𝑛𝑔

𝑏𝑎𝑟 𝐴𝑏𝑎𝑟

𝑠𝑡𝑒𝑒𝑙 𝐴𝑏𝑎𝑟

𝑙𝑑2 =

𝑙𝑑3 =

𝑙𝑑 𝑚𝑖𝑛

0.02 ∙ 𝑂𝐷𝑏𝑎𝑟 ∙ 𝐹𝑦−𝑏𝑎𝑟 𝑓′𝑐 12 0.02 ∙ 𝑂𝐷𝑏𝑎𝑟 ∙ 𝐹𝑦−𝑏𝑎𝑟 𝑓′𝑐 ∙ 1.2 12 0.0003 ∙ 𝑂𝐷𝑏𝑎𝑟 ∙ 𝐹𝑦−𝑏𝑎𝑟 = 12

𝑙𝑑2 𝑙𝑑 = 𝑚𝑎𝑥 → 𝑙𝑑3 𝑙𝑑 𝑚𝑖𝑛

𝑐𝑎𝑠𝑖𝑛𝑔

+

𝐸𝑆 𝐿2𝑐𝑎𝑠𝑖𝑛𝑔 𝜋2

127.168 63.8581

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