example 6 1 rectangular water tank design
DESCRIPTION
rectangular water tank design example using working stress method of designTRANSCRIPT
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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Example 1
A rectangular R.C water tank with an open top is required to store 80000 liters of water. The
inside dimensions of tank may be taken as 6mx4m. Design the side walls of the tank using C-20
concrete and steel of class I. Assume free board of 15cm.
= 9.5 8 + 13 = 9.5 8 + 16 1/3 = 27.4
=
=200
27.4= 7.3 , =
+
=7.3
7.3 +100
7
= 0.34,
= 1
3 = 0.89, = 0.5 = 0.5 7 0.34 0.89 = 1.06
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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Example 2
A reinforced concrete water tank resting on ground is 6mx2m with a maximum depth of 2.5m.
Using C-20 concrete and Grade I steel design the tank walls.
1. Data
Size of tank=6mx2m
Depth of tank=2.5m
C-20 concrete and steel with Class 1
2. Permissible stresses
= 7/2
= 100/2
= 125/2
=200
27.4= 7.3
=
+
=7.3
7.3 +100
7
= 0.34
= 1
3 = 1
0.34
3= 0.89
= 0.5 = 0.5 7 0.34 0.89 = 1.06
3. Dimension of tank
L=6m; B=2m
=
6
2= 3 > 2
Long walls are Designed as vertical cantilevers and short walls as slabs spanning
horizontally between long walls.
4. Design of Long walls
:
=3
6=
10 2.53
6= 26.04.
=
=
26.04 106
1.06 1000= 156.74
Using 16mm diameter bars and 25mm effective cover up to center of rebar
Over all Depth D=d+ cover = 156.74+25=181.74
Take t=D=185mm
Effective depth d=185-25= 160mm
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
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=
=
26.04 106
100 0.89 160= 1828.652
16 =1000 201
1828.65= 109.92
Provide 16 mm diameter bars at 100mm c/c spacing.
Intensity of pressure at H/4 or 1m whichever is greater H/4 =2.5/4 =0.63 or 1m
At h = 1m from base is the largest
= = 10 2.5 1 = 15/2
Direct tension in Long walls
=1
2 =
15 2
2= 15
=
=
15 1000
100= 1502
But minimum area Ast min =0.3% Ag
Ast min = 0.3% Ag =0.3
100 185 1000 = 555 2
spacing of 10mm diameter bars S =1000 79
555= 142.34
since steel is provided on both faces, provide 10 mm diameter bars at 280 mm c/c on both faces.
5. Design of short walls
P = 15 KN/mm2
effective span of horizontal slab B = 2+0.185=2.185
Bending Moment at corner section
=2
12=
15 2.1852
12= 5.97
= 1 = 15
= 160 185
2= 67.5
=
+
=
5.89 106 15 67.5
100 0.89 160+
15 1000
100= 563.552 >
10 =1000 79
563.55= 140.18
Provide 10mm bars at 140 mm c/c.
Bending Moment at mid section
=2
24=
15 2.172
24= 2.94
T=15KN
=
+
=
2.94 106 15 67.5
125 0.89 160+
15 1000
125= 285.112 >
2
= 277.5
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HAWASSA UNIVERSITY IOTECH SCHOOL OF CIVIL AND URBAN ENGINEERING ADVANCED STRUCTURAL DESIGN (CENG 5721) EXAMPLES FOR CHAPTER 6
Page | 7
10 S =1000 79
285.11= 277.09
Hence at mid span provide minimum horizontal reinforcements on inner face and Provide 10mm
diameter bars c/c 275mm on outer faces.
6. Design of cantilevering effect of short wall
. =1
6 2 =
1
6 10 2.5 12 = 4.17
Effective depth using 10mm bars= 185-25-5=155mm
=
=
4.17 106
100 0.89 155= 302.282
10 S =1000 79
302.28= 261.35
Hence Provide 10mm diameter bars c/c 260mm on inner faces and minimum rebar on the outer
faces in the vertical direction.