example # 2 بسم الله الرحمن الرحيم design of concrete structure ii university of...
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Example # 2
الرحمن الله بسمالرحيم
Design of Concrete Structure II
University of Palestine
Instructor:
Eng. Mazen Alshorafa
Design the two way solid slab shown in Figure. The covering materials weigh 2.3 KN/m2 and the live load is 3.2 KN/m2. Also, Calculate the factored load acting on beam 1 due to slab.Use fc’ = 25 MPa, fy = 420 MPa. All beams are 250mm wide
Example # Example # 22
3m 5m 5m
4m
4m
4m
C16
C15
C14
C13
C12
C11
C10
C9
C8 C7 C6 C5
C4 C3 C2 C1
Beam
1
Page 0Instructor:
Eng. Mazen Alshorafa
الرحمن الله بسمالرحيم
Design of Concrete Structure II
University of Palestine
SolutionSolution1- Evaluate slab thickness: Ln,max = 5.0 – 0.25 = 4.75 m = 4750 mm
The largest slab thickness is given by
Use a slab thickness of 140 mm =14 cm
2- Determine the total factored load per unit area of slab: wu = 1.2[0.14(25)+2.3] + 1.6(3.2) = 12.1 KN/m2
wu = 12.1 KN/m2 =1.21 t/m2
mm
fylh n
5.14236
)1500/4208.0(475036
)1500/8.0(max
Page 1Instructor:
Eng. Mazen Alshorafa
الرحمن الله بسمالرحيم
Design of Concrete Structure II
University of Palestine
3- Evaluate load distribution in both directions:
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
S1
S5
S4
S3
S6
S7
S8
S2
Based on Egyptian code load coefficients:
For panel S1,S2 and S8:
For panel S3 and S6:
For panel S4:
23.0475.0
,25.1)87.0(0.4
)87.0(0.5'
and
r
190.0517.0
,33.1)87.0(0.3
)87.0(0.4'
and
r
23.0475.0
,25.1)76.0(0.4
)76.0(0.5'
and
r
Page 2Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
3- Evaluate load distribution in both directions:
For panel S5:
For panel S7:
For all panels,For a strip 1m wide,
ws = α wu
wl = β wu
295396.0
,092.1)87.0(0.3
)76.0(0.5'
and
r
174.0565.0
,43.1)76.0(0.4
)87.0(0.5'
and
r
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
S1
S5
S4
S3
S6
S7
S8
S2
Page 3Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
Loads in both directions:
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
5.75 KN/m2
2.78 KN/m2
5.75 KN/m2
2.78 KN/m2
5.75 KN/m2
2.78 KN/m2
4.79 KN/m2
3.57 KN/m2
6.84 KN/m2
2.10 KN/m2
5.75 KN/m2
2.78 KN/m2
2.30 KN/m2
6.25 KN/m2
2.30 KN/m2
6.25 KN/m2
Page 4Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
4- Select Representative 1m wide design strips to span in short and long direction.
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
Strip #1
Str
ip #
4 Strip #2
Strip #3Str
ip #
5
Strip #6
Page 5Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
5- Design each stripFor Example, take Strip # 1
5 m 5 m
2.78 KN/m
S.F.D
B.M.D
5.2 KN8.7 KN
8.7 KN 5.2 KN
8.7 KN.m
4.9 KN.m4.9 KN.m
Average effective depth (davg)
davg =140-20-12 = 108 mmAssuming that dstirrup = Φ 8 && dbar = Φ12
A - Check slab thickness for shear
KOKNN
dbfc
V wc
....5.6767500
10810006
25*75.0
6
'
Page 6Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
Design of Strip # 1(Contd.)
5 m 5 m
2.78 KN/m
5.2 KN8.7 KN
8.7 KN 5.2 KN
8.7 KN.m
4.9 KN.m4.9 KN.m
B- Design of reinforcement
mmUsemmAsAs
mKNMFor
mmUsemmAsAs
mmAs
mmAs
dbfc
M
fy
fc
req
u
req
req
w
u
300@10.252
.9.4
300@10.252
252140*1000*0018.0
.218108*1000*002.0
0020.0
)108)(1000)(25()9.0(85.0
)7.8()10(211
420
25*85.0
'85.0
)10(211
'85.0
2min
2min
2min
2
2
6
2
6
Φ 10 @ 300 mm
Φ 10 @ 300 mm Φ 10 @ 300 mm
Page 7Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
Check slab thickness for beam shear for each strips and determine the required amount of reinforcement for each strips then prepare neat design drawings showing slab thickness and providing reinforcement.
140
mm
Sec. A-A
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
Φ 10 @ 300 Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300 Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300 Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300
Φ 10 @ 300
Page 8Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
3m 5m 5m
4m
4m
4m
C16 C15 C14 C13
C12 C11 C10 C9
C8 C7 C6 C5
C4 C3 C2 C1
140
mm
Sec. A-A
Φ 10 @
300 Φ
10 @ 300 Φ
10 @ 300
Φ 10 @
300 Φ
10 @ 300
Φ 10 @
300 Φ
10 @ 300 Φ
10 @ 300
Φ 10 @
300 Φ
10 @ 300
Φ 10 @
300 Φ 10 @
300 Φ
10 @ 300
Page 9Instructor:
Eng. Mazen Alshorafa
Design of Concrete Structure II
University of Palestine
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