Single Pilecap 182

DESIGN OF SINGLE PILE CAP DATA:-

Pile Diameter

: 400 mm

Column Dimension B x D

: 400 x 600 mm

Axial Load

: 600 KN

Concrete Mix

: M20

Steel Grade

: Fe 415

DESIGN : 1.

Pile Cap Dimension :

Width of Pile Cap = ( hp + 2 x 150 ) = 400 + 150 + 150 = 700 mm Depth of Pile cap 2.

= 2 hp + 100 = 2 x 400 + 100 = 900 mm.

Net Upward Pressure :

Pu = 1.5 x 600

= 900 KN = 1836.73 KN / m 2

Upward Pressure = 900 0.7x 0.7 3. Bending Moment :-

Projection = 0.70 – 0.40 = 0.15 m 2 B.M. in Pile cap at section A – A

2

Mu = 1836.73 x 0.15  /2 = 20.66 KN.m

4. Check for effective depth : 2 6 Mu = 0.138 f ck ck b d = 20.66 x 10

d required = √ (20.66 x 10 6 ) / 2.76 x 700 = 103.40 mm D provided = 900 mm d available = 900 – 60 60 -12- 6 = 822 822 mm > d required i.e. i.e. 103.4 mm 5. Check for Punching Shear : -

As single Pile is provided, the cap has to be checked for punching shear. Area resisting punching = (600 x 2 + 400x 2) x 822 =( 2000 x 822 ) mm Punching stress

= 900 x 103 2000 x 822

= 0.550N/mm 2 < 1.12 N/mm 2

6. Main Reinforcement : -

Mu = 20.66 KN.m 2

K = Mu  / bd = 20. 66 x 10 700 x 822

6

= 0.04 < Table value

2

Minimum Ast = 0.12 x 700 x 822 = 690.48 mm 2 100 Provide 12 mm Dia RTS @ 110 mm c/c both ways at bottom. Provide same at top along perpendicular direction of main reinforcement. 7. Check for one way shear :-

Shear force at section A – A at a distance d/2 = 822 /2 = 411 mm from face of  column = 1836.73 x 0.15 x 0.70 = 275.51 KN Shear stress = 275.51 x 10

3

= 0.48 N/mm

2

822 x 700 Ast provided = 113 x 700/110 = 719.71 mm

2

Pt = 719.71 x 100 = 0.13 % < Minimum P t of Table value of shear stress 700 x 822 For Pt = 0.20% ζ c from Table 61 of Design Aid to IS 456 -1978 = 0.33 N /mm 2 Balance shear Vus =275.51 – (0.33 x 700 x 822 x 10 -3) =85.628 KN. Vus /d = 85.628 / 82.2 =1.042 KN/cm Provide 8 Φ RTS 2 legged stirrups @ 150 mm c/c.