Thrust Block Calculations

Project :

Date : 11/26/2011

logo Page No. :

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/

Description :

THRUST BLOCK

Checked by :

Designed by :

Drawing No. : /

HORIZONTAL BENDS

gs = m = f = gc =

Compressive strenght of concrete;

f'c =

Concrete Elastic Modulus

Ec =

Yield strenght of steel;

fy = Es =

Elastic Modulus of steel Width of the block ; Height of the block ; Max. Length block of the per direction ; Depth of the earth cover; Height from top of the block to NGL ;

H1 = H2 =

Height from top of pipe to NGL ; Total length of the block ;

H3 = l =

1.) Determine design presure ; d d = design (total) pressure = [HGL 26.13 m

d

=

346.225

x

9.81 kN + m3

H3 = 2.18

1.8 3.8

5.50 m 124.46 kg/m 3 18 kN/m 0.5 25 23.54 kN/m3 27.5 MPa

W1

W2

P W3 E

B

l =

24647 413 MPa 200 GPa 2 m 2 m 1.15 m

B = H = L1 = L2 =

Min. Length block of the per direction ;

FGL

H =

FGL = Wr =

Unit weight of soil; Soil friction coeffiecient Angle of internal friction ; Unit weight of concrete;

=

degrees m Bar mm 12.45 mm 2.11 m

H2 =

Finish Ground Level Weight of the pipe

45.88 26.128 2.284 1224.9

2.00 H1 =

DESIGN CONSIDERATION : STA 0 + 67.904 (N 41301.17 E 62710.408) BEND: DN1200 X 45.88 q = Hydraulic gradeline ; HGL = rs = Surge Pressure D = Pipe outside Diameter; Pipe thickness; t = EL = Inverted Level :

L

=

2.0

=

2 2.1 L2 = 2.0

2.0

2

q 2

2.00 m 1.79 m

1.2

3.79 m 2.18 m 2.1 m

L

L1

= 22.9

= 1.2

=

1

3 9.81 Kn/m + surge pressure] 1.4 2.28 BarG x 100 kPa 1BarG 1.4

x

kPa

2.) Determine Thrust force; R (Horizontal bend) AS PER AWWA M 45 7.1 where d= Design (total) pressure A = Area of the Nominal area of the pipe P = 2dA sin ( q ) = 2 x 346.225 kN x[( 1.22 m)2x( p )] x sin 45 2 4 2 m2 P = 312.263 kN m ***Assume block size to be; 2 m B = H =

2

m

L

=

1.58 m

= 2.125 m

l

3.) Weight of soil on the block; W 1 W 1 = gs X h1 X 2L 18.00 kN X = W1 =

B 1.79 m

X

X

2(

1.58 m)

X

2

m

203.213 kN

4.) Weight of water and pipe in the block;

W2

W 2 = gw = W2 =

2AL + Wr 9.81 kN X 2( m3 38.838 kN

1.13 m2 ) x(

1.58 m) +

(

124.46

kg X 9.81 m m sec2 1000

)

X 1.58 m x

2 m

Project :

Date : 11/26/2011

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Description :

THRUST BLOCK

Checked by :

Designed by :

Drawing No. : /

HORIZONTAL BENDS

5.) Weight of block; W 3 23.54 kN [( = m3 W3 =

m)x(

2

2

m) -

( p )( 4

2 1.22 m) ]

2 x

1.58 m

209.459 kN

6.) Total weight ; W W = W1 + W2 + W3 = 203.213 kN + m W = 451.510 kN

38.838 kN + 209.459 kN m m

7.)Friction force ; F F F

= mW = 0.5 = 225.755 kN

x

451.510 kN m

8.) Passive Pressure earth pressure at the back of the block ; E E

E

= 1 Cw gs (h22-h12) l 2 = 1 x tan2 ( 45 + 25 )x 2 2 = 390.2094 kN

9.) Total resistance force ; R = F + E R = 615.96

kN x[( 3.79 m)2- ( 1.79 m3

18

m)2]x 1.58 m

R

= 225.755 kN + 390.209 kN kN

10.) Safety FactorF.S. ; F.S. = R = P

615.964 kN = 312.263 kN

1.97

The calculated factor is larger than 1.5, therefore this block is satisfactory

11.) Check base stability

2

2.1 l =

SOIL BEARING CAPACITY Pb=

98.100

kN/m

2

REQUIRED AREA Areq Areq

.=

W total Soil Bearing = 4.603

=

451.510 kN/m 98.100 kN/m2

L

=

L2 =

2.0

2

q = 45.88

Aact.

=

L1 2 1 B ( L1 + L2 ) x 2 = 1 x 2.00 m( 1.15 m + 2.00 m ) x 2 2 2 = 6.307 m since Aact.> Areq. THEREFORE Use Aact. =

B

m2

ACTUAL AREA Aact.

2.0

1.2

L1 =

1.2

Project :

Date : 11/26/2011

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Description : Designed by :

THRUST BLOCK

Checked by :

Drawing No. : /

HORIZONTAL BENDS

NET ULTIMATE UPWARD SOIL PRESSURE qnet

= W total x

1.7

qnet

=

451.51 kN/m

=

Aact.

6.31

x m2

1.7

kN/m3

121.70

ALLOWABLE ULTIMATE SOIL PRESSURE qult

=

qult

=

PB

x

1.7 X W total

166.77

W total q ult > q net SAFE !!!!

I.] DESIGN SPECIFICATIONS : 1.1 ACI 318-02 & PCA NOTES ON ACI 318-02 II.] MATERIALS :

(Input Data)

: Unit Weight of soil,

gc = gs =

23.540 kN/m3 18.000 kN/m3

2.2 Concrete

: Compressive Strength, Cover to Main Bars,

f'c = c =

27.500 MPa 75.000 mm

2.3 Deformed Bars

: Yield Strength, Main Bar Diameter,

fy = DM = DT =

413.000 MPa 16 mm

2.1 Loads

: Unit Weight of concrete,

T & S Bar Diameter, 2.4 Slab

: Length, Width, Slab Thickness, Height of soil,

L W t H1

16 mm 1.612 3.154 0.400 1.790

= = = =

m m m m

III.] CALCULATIONS : FIGURE :

1.79 m

L

2.00 m

W

Wu

1.61 m

L DESIGN FORCES : Min. t = ( L / 20 ) [ 0.40 + ( fy / 700 ) ] = ( 1612 / 20 ) [ 0.40 + ( 413 / = 79.82 mm use 400 mm Consider 1m strip : Wt. of slab = ( 0.40 ) ( 3.15 ) = 29.69 kN/m Surcharge

= =

Overburden Soil

( 23.54 )

1.00 m x 3.154 56.763 kN/m = =

1.79 x 3.154 2 101.606 kN/m

x

18.000

x

18.000

700

)]

Project :

Date : 11/26/2011

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Description :

THRUST BLOCK

Checked by :

Designed by :

Drawing No. : /

HORIZONTAL BENDS

Total design load : 1.4 W DL + 1.7 W S 1.40 x 29.69 + 41.57 + 269.23 310.80 kN/m

Wu = = = =

2 Mu = Wu * L / 12 2 = 310.80 x ( 1.61 ) = 101.01 kN-m

158.37

x

/ 8

Mu

=

x

1.70

where :

øbd2fy =

=

(0.9)

x =

d = t - c - DM/2

( 1.00 )

101.010 ( 0.317 )

2

317.000

x 10-3

413

2.7043E-03

m = fy / 0.85f'c = 17.668 rreq'd = [1 - (1-2mx)] / m = 0.002772 rmax

use r =

=

0.75 (0.85) (0.85) ( 28 ) ( 600 ) 413 ( 600 + 413 ) As req = rbd = 878.78

0.0028

Ab = p (DM)2 / 4 = 201.062 Min S = Max S =

( b ) ( fc' ) (600) 600 + fy )

(0.75) (0.85) ( fy = 0.021 =

\ USE :

S = (Ab / As req'd) mm = 228.80

mm2

100 mm ( 600 mm

450 mm

,

ø16mm @

TEMPERATURE BARS

mm2

)

220mm O.C.

( ø16mm )

As = 0.0020bh =

0.002

x

=

800

mm2

Ab = p (DT)2 / 4 = 201.062 Min S = Max S =

1000

S = (Ab / Min As) (b) = 251.327 mm

mm2

100 mm ( 2000 mm

\ USE :

x 400.000

,

450 mm

ø16mm @

)

250mm O.C.

CHECK FOR SHEAR : Vu = ( 29.69 ) =

219.49

( 1.41 ) kN

( 0.50 )

( 1.40 ) +

( 158.4 )

( 1.41 )

( 0.50 )

( 1.70 )

mm

Project :

Date : 11/26/2011

logo Page No. :

-

/

Description :

THRUST BLOCK

Checked by :

Designed by :

Drawing No. : /

HORIZONTAL BENDS

Using 0.50 m thickness of concrete at face of support :

=

0.85

therefore :

x

=

277.06

27.50

=

( 1000.00 ) 6

317.00

=

277.06 kN

235.50 kN

VU < VC ;

Safe !!!

ø16mm @

250mm O.C.

ø16mm @

2.00 m

fVc

fc bw d 6

220mm O.C.

DN1200 X 45.9

H =

Vc =

B

= 2.00 m