CE 318
STRUCTURE ANALYSIS AND DESIGN II LAB
LECTURE 8
PILE CAP DESIGN
SEMESTER: FALL 2020
COURSE TEACHER: SAURAV BARUA CONTACT NO: +8801715334075
EMAIL: [email protected]
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LECTURE PLAN
Load on pile cap
Pile cap size
Pile layout
PILE CAP GROUP
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LOAD CALCULATION
• Take load coming from corresponding column
• Consider 10% self weight for pile cap
• Load on Pile cap = 1.1 x load on corresponding column
Pile cap
Corresponding Column
Load on columns (from
Lecture 7) kip
Consider 10%
self weight for pile cap
Load on pile cap (kip)
PC1 C1 228.38 22.84 251.22
PC2 C2 425.15 42.52 467.67
PC3 C3 388.80 38.88 427.68
PC4 C4 776.16 77.62 853.78
PILE CAP SIZE
• Pile capacity = 100 kip (Assume, obtained pile capacity from soil test report)
• Also, Assume, pile diameter = 16” and length = 40’
• Type is cast in situ pile embedded into hard soil strata as per geotechnical report.
pile capacity calculated from end bearing and skin friction [Detail explanation in class lecture!!!]
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• Pile to pile distance must be 3d = 3 x 16” = 48” = 4’-0”
Based on this we have to calculate pile cap size
No of pile required = load on pile cap/ pile capacity
Pile cap
Load of pile cap (kip)
Capacity of individual pile
(kip)
Nos. of pile required
PC1 251.22 100 3
PC2 467.67 100 5
PC3 427.68 100 4
PC4 853.78 100 9
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PC1 pile cap Nos. of pile = 3
Length of PC1 = 1.5 d x 2 + 3d = 1.5 x 16 x 2 + 3x 16
= 96” = 8’-0”
Short length of PC1 = 3d = 3 x 16 = 48” = 4’-0”
• Similarly width of PC1 = 8’-0”
• So, PC1 pile cap size = 8’-0” x 8’-0”
1.5 d for clear cover (explain in class lecture)
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PC2 pile cap Nos. of pile = 5
Length of PC2 = 1.5 d x 2 + 3√2 d = 1.5 x 16 x 2 + 3√2 x 16
= 115.88” ≈9’-8”
• Similarly width of PC2 = 9’-8”
• So, PC2 pile cap size = 9’-8” x 9’-8”
PC 3 length (4nos. Pile) = 3d + 1.5 d x 2 = 6d = 6 x 16 = 96” = 8’-0” (both sides) Size of PC 3 = 8’-0” x 8’-0”
PC 3 length (9nos. Pile) = 3d x 2+ 1.5d x 2 = 9d = 9 x 16 = 144” = 12’-0”
Size of PC 4 = 12’-0” x 12’-0”
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Pile cap Nos. of pile Size
PC1 3 8'-0" x 8'-0"
PC2 5 9'-8" x 9'-8"
PC3 4 8'-0" x 8'-0"
PC4 9 12'-0" x 12'-0"
PILE LAYOUT
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