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Jirgo Dam Parapet Wall Design

The document provides design details for a parapet wall to be constructed on top of the Jirgo Dam. Wind loads were calculated based on the dam height and factored to determine horizontal forces on the wall. The weight and dimensions of the proposed RCC wall were calculated. Checks were performed to ensure the wall design is safe against sliding, overturning, and bearing pressure. Reinforcement requirements were determined for the base slab and vertical wall. Bars of 10mm and 8mm diameter are proposed to be provided at 200mm centers.

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govind narayan Shukla
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329 views4 pages

Jirgo Dam Parapet Wall Design

The document provides design details for a parapet wall to be constructed on top of the Jirgo Dam. Wind loads were calculated based on the dam height and factored to determine horizontal forces on the wall. The weight and dimensions of the proposed RCC wall were calculated. Checks were performed to ensure the wall design is safe against sliding, overturning, and bearing pressure. Reinforcement requirements were determined for the base slab and vertical wall. Bars of 10mm and 8mm diameter are proposed to be provided at 200mm centers.

Uploaded by

govind narayan Shukla
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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IRRIGATION DIVISION CHUNAR, MIRZAPUR

Design of Parapet wall at Top of Jirgo Dam

As per DSPR recommendation we have to provide a parapet wall on top of the


dam. For this purpose we have taken into consideration the self weight of wall
which acts vertically along the c.g. of the wall and horizontal wind pressure
which act laterally with equal pressure distribution, so collectively it can be
assumed that it act at the half of the height of the exposed surface.
As per guidelines of IS Code 875 part (3) wind pressure depend height of
structure.
Height of the Dam from avg. GL/DSL = (328-282)= 46 feet = 14 m.
Wind pressure @ 14 m = 107 Kg/m2
Horizontal force at parapet wall = 1.2x1.0x107x9.81 = 1259 N/m
H = 1.26 KN/m
Assuming a RCC wall of thickness 0.15m and height 1.2 m above dam top level
and 0.40 m below top of dam with a width of footing 1.0m and thickness as
0.20m.
Weight of wall,
W = 1x1.20x0.15x25 = 4.5 KN/m

∑V=W=4.5 KN/m x1=0.50 m from toe

∑H=H=1.26 KN/m x2=0.40+0.60=1.0 m from toe

Restoring Moment, MR = 4.5x0.5 = 2.25 KN-m

Overturning Moment, Mo = 1.26x1.0 =1.26 KN-m

Factor of Safety Against Sliding : (Assuming µ=0.5)


μ ∑V 5.0 x 4.45
=
∑H
= 1.26
= 1.785 > 1.55 Hence Safe
Factor of safety against overturning :
MR 2.25
=
Mo
= 1.26
= 1.785 > 1.55 Hence Safe

Maximum Pressure at base


M 2.25−1.26
=
V
= 4.50 = 0.22
B 10
e= −x = −0.22 =0.28
2 2
Maximum Pressure at base

Pmax= ( )== 4.5


V
b
1+
2e
b
1.0 ( 1+
6.0 x 0.28
1 ) = 12.06KN/m2

Pmin= ( 1+ )== (1+ )


V 6e 4.5 6.0 x 0.28
b b 1.0 1
= -3.06KN/m2

Design of Base slab :


Assuming a clear cover of 20 mm dia of bar as 10 mm,
10
effective depth available, d =200 - 20- =175 mm
2

wl 2
Maximum Bending Moment =
8
12.06 x (1.00)2
= = 1.5075 KN-M
8
Required depth of footing

=
√ M
Rxb
where R=0.911

√
6
= 1.5075 x 10 = 40.67 mm > 175 mm hence safe
0.911 x 1000

Area of steel required


1.5075 x 10 6
= = 41.43 mm2
0.904 x 175 x 230
78.53 x 1000
Taking 10mm  bars, spacing = 41.43
= 1895 mm

Provide 10 mm  bars @ 200 mm c/c at the base slab as per


Checking shear stress :
Shear force at artical section d= 0.200 from face of wall
12.06+8.67
S.F. = x 0.225=2.332 KN
2
2.332 x 1000

Nominal shear stress = v = 175 x 1000 =0.013 N/m

c from table 23 of IS 456-2000


1000 xAs 100 x 5 x 78
P%= =
bxd 1000 x 17.5
0.22−0.18
c = 0.18 + 0.25−0.15 (0.224−0.15)

= 0.2096 > 0.013 Hence Safe


Distribution steel
Astd = 0.12% of Sectional area
0.12
= x 200 x 1000 = 240 mm2
100
78.54 x 1000
Spacing for 10mm  bar = 240
= 327.25 mm c/c

for syrreptry Providing 10 mm  bars 200 mm c/c


Design of Vertical Parapet wall
Ht. of wall above base slab = 1.40 M
GL = 1.20 M
Intensity of horizontal wind pressure = 1.20x1.0x107x9.81 =1.26 CN/m
Wl2 1.26 x 1.22
Maximum BM for Continuous beam action = = = 0.1512 KN-m
12 12
0.1512 x 10 2
Area of steel required =
0.904 x 150−20( 10
2
x 230 )
Hence providing Minimum = 58.17 mm2 (Very less)
Area steel on .12@ of x-section
0.12
= x 150 x 1200 = 216 mm2
1000
Providing 10 mm  bars @ 200 mm c/c
1.26 x 1.20
Shear Force = = 0.756 KN
2
756
 v= 1000 x 125 =0.006 N/mm2 (Very less)

Hence Safe
Hence providing 8 mm  bars @ 200 mm c/c

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