Structural Design of Pile 400 MM DIA

STRUCTURAL DESIGN OF PILE 400 MM DIA (TOP 12. 6 NO. ONLY) Diameter of pile = Working Load (Compression) P = Load Factor (Ref.Table 2.2 of BS:8110 :1997, Page 9)=

400 mm 1000 kN 1000 x 1.5

=1500 kN

Structural Design of Pile I) Material properties : a) Characteristic cube strength of concrete = Fcu- 40 Mpa b) Characteristic strength of steel = Fy –Gr. 420– 420 Mpa II) Proposed Reinforcement: a) Main Reinforcement = 8T16 mm dia b) Shear Reinforcement = T10@ 150 c/c helical links (Ref. 3.12.7.1 & 3.12.7.2 of BSS 8110-1:1997, Page 79) III) Pile Details Pile size Clear cover Working load Fcu

= = = =

400 mm dia. 75 mm 1000 kN 40 N/mm2

Fy

=

420 n/mm2

Section Area Main Reinforcement Dia. No. of Rods Reinforcement area of 16 mm Dia

= = = =

125600 mm2 20 mm 8 nos. 2512 mm2

IV) Check for Stresses in Concrete: Referring to clause 7.4.4.3.1 of BS : 8004 – 1986, allowable compressive stress under working load should bot exceed 25% of the specified works cube strength at 28 days calculated on the total cross sectional area of the Working stress Allowable Stress

= = =

1000 x 1000 (3.14/4 x 400 ^2) 4.906 N/ mm2 0.25 x 40 = 10.00 N/mm2 ¾ 4.906 N/mm2 Hence O.K.

Check for compression capacity of piles referring to BS: 8110 (Part-I, Clause 3.8.1.3). Since the 'N' value of soil is high in top layers so there is no unsupported length of the pile Slenderness is not taken. BS 811-1 Cl. 3.8.1.3 Referring to BS: 8110 part-I, Clause 3.8.4.3 for nominal eccentricity of short columns resisting moments and axial forces, which stress that the column may be designed. So that the design axial load does not exceed the value of N given by. N = 0.4 x Fcu x Ac + 0.8 x Asc x Fy = 0.4x40x 125600+0.8x2512x420 2853632 N = 2853.632 kN Allowable compressive load =

2853.6 >

1000 x 1.5 2500 kN

Hence safe V) Design of pile due to axial load and Bending: Axial Load Load Factor (Ref: Table 2.1 of BS:8110-1:1997, Page 8) Factored axial load, P = Moment is taken from the graph =

1000 x 1.2 39.0

Factor Moment,

39 x 1.2

=

= 1200 kN =39.0 kN-m = 46.8 kNm

Design Moment M = 46.8 = 46.8 kNm (Referring to CP:110 Part-3 Page No. 132 for circular sections-Available lower grade chart is considered) Fcu = 40N/mm2 Fy = 420N/mm2 h = 400 mm hs = 400 – (2x75) – 2 x 10 = 230

Hs/h

=

230/400

=

M/h3 P/h22

= =

46.8 x 10^6 / 400^3 1200 x 10^3 / 400^2 Hence O.K.

Shear Check: Factor Moment, M Factored vertical Load, P M/P 0.6 h

= = = 46.8 / 1200 = 0.6 x 0.4

0.57 0.73125 7.50

46.80 kNm 1200kN =0.039 m 0..24 m M/P < 0.6 h Shear check is not required (As per BS:8110-1, 1997 Cl.3.8.4.6 shear check is not required) VI) Design Summary Diameter of Pile Grade of concrete Grade reinforcement steel Main reinforcement Helical reinforcement

400 mm OPC40 420 N/ mm2 8 T 20 T 10 @ 150 c/c helical links