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Check Beam Shear. 245. 166. 245. Bending moment design. 2.5m. Short direction. Central band ratio =. Central band of short direction = 0.83 As = 0.83 (10.1)=8.6cm 2. Footing Design Part II Combined footing. Example 1. Design a combined footing As shown. Dimension calculation - PowerPoint PPT Presentation
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Check Beam Shear
5.567
5.2*53.05.1*2
245223
facecolumn from at
13.8281000/25005306
2575.0
CU
U
U
C
VV
kN
V
dV
kNV
direction short 1.1010601000530002.0
0.002 3500*530*250.859.0
719.25*102-1-1
420
25*85.0
305d ,3500b
.25.7195.05.312
166245
facecolumn from dat
22
2
6
cmmmA
mm
mkNM
M
S
U
U
Bending moment design
Short direction
245
245
166
2.5m
0.832.4
2
1
2
1.42.5
3.5
Central band of short direction = 0.83 As = 0.83 (10.1)=8.6cm2
Central band ratio =
14/m7 142 142
16/m7
Footing Design Part II
Combined footing
Example 1Design a combined footing As shown
kPamtq netall 200/20 2)( 225 mmNfc 2420 mmNf y
Dimension calculationThe base dimension to get uniform distributed load
x2=6.2mx1=0.2m
800 kN 1200 kN
x
2000kN
A
800(0.2)+1200(6.2)=2000(x)x = 3.8m
2x =7.6 m
800 kN 1200 kN
Try thickness =80cm
kPaPa
A
Pq
mq
PA
kNPP
kPamtq
uu
netall
sg
su
netall
190101908.1*6.7
102600
8.1*6.71010200
102000
2600)2000(3.1)(3.1
,200/20
33
23
3
)(
2)(
Area required
Check for punching Sheard = 730 mm
oK 8.875190*765.0*13.1)3.1(800
60271000/226073012
25
2260
73030275.0
12
'2
3.20621000/22607303
2575.0
3
'
22601130)765(2
V kNV
kNdbf
b
dV
kNdbf
V
mmb
cU
ocs
C
oc
C
o
A
1.13m
0.765
oK 4.1317190*13.1*13.1)3.1(1200
5.133221000/452073012
25
4520
73040275.0
12
'2
4.41241000/45207303
2575.0
3
'
4520)400730(4
V kNV
kNdbf
b
dV
kNdbf
V
mmb
cU
ocs
C
oc
C
o
B
Draw S.F.D & B.M.D
Stress under footing = 190 *1.8 = 342 kN/m
34.762facecolumn from at .
25.8211000/18007306
2575.0
CU
U
C
VV
kNdVMax
kNV
Check for beam shearb = 1800mm, d = 730mm
Top /209 5.28284710007300039.0
0.0039 1800*730*250.859.0
1366*102-1-1
420
25*85.0
307d ,8001b
.1366
22
2
6
musecmmmA
mmmm
mkNMve
S
Bending moment Long direction
Bottom /167 4.14144010008000018.0
0.0007 1800*730*250.859.0
246.7*102-1-1
420
25*85.0
307d ,8001b
.7.246
22min
min2
6
musecmmmA
mmmm
mkNMve
S
Bending moment Short direction
/147 116.11017658000018.0
765*730*250.859.0
141.6*102-1-1
420
25*85.0
307d ,765b
6.1412
4.08.1
2
765.0
)765.0*8.1(
1040
22min
min2
6
2
musecmmmA
mmmm
M
S
Under Column A
/147 116.11017658000018.0
1130*730*250.859.0
212.33*102-1-1
420
25*85.0
307d ,1130b
33.2122
4.08.1
2
13.1
)13.1*8.1(
1560
22min
min2
6
2
musecmmmA
mmmm
M
S
Under Column B
Shrinkage Reinforcement in short direction
/147 116.11017658000018.0 22min musecmmmAS
Footing Design Part III
Combined footing, strip footing, & Mat foundation
Example 2Design a combined footing As shown
kPamtq netall 180/ 18 2)( 225 mmNfc 2420 mmNf y
Dimension calculationThe base dimension to get uniform distributed load
x1=0.2mx2=4.2m
1200 kN 750 kN
x
1950kN
A750(4.2)+1200(0.2)=1950 (x)x = 1.75m
3
2
21
21 L
BB
BBx
mB
mB
B
BL
BB
BBx
BB
BB
BB
LBB
mq
PA
kPamtq
netall
sg
netall
4
1
29.045.175.1
3
35.4
5
5
3
2
5
5.22
8.1035.42
8.102
8.1010180
101950
,200/20
1
2
2
2
21
21
21
21
21
21
23
3
)(
2)(
Area required
kPaPa
A
Pq u
u 235102358.10
1019503.1 33
Check for punching Shearh= 750mmd = 732 mm
oK 6.1376235*733.0*065.1)3.1(1200
52221000/259066512
25
2590
66530275.0
12
'2
4.21601000/25906653
2575.0
3
'
25901065)732(2
V kNV
kNdbf
b
dV
kNdbf
V
mmb
cU
ocs
C
oc
C
o
A
B1=4m
B2=1m
B
oK 5.896235*633.0*965.0)3.1(800
52731000/223166512
25
2231
66530275.0
12
'2
5.18541000/22316653
2575.0
3
'
2231965)633(2
V kNV
kNdbf
b
dV
kNdbf
V
mmb
cU
ocs
C
oc
C
o
Draw S.F.D & B.M.D
mkN
wlM
wave
. 11748
65.3705
8
705)235940(23522
max
32
Mmax
68270.0975
1092)70.0(1560
Empirical S.F.D & B.M.D
m
Convert trapezoidal load to rectangle
Clear distance between columnB in moment design = ave. width = 2.5m
668critical)most the( face Bcolumn from at .
6961000/17006656
2575.0
17007.15.1)(21
0.150.815at
)(21
35.4965.0
CU
U
C
Lx
VV
kNdVMax
kNV
mmm
x
yb
Check for beam sheard = 665mm
Y=1.5m
1m
4m
x
b
Top /1601 2019951000665003.0
0.003 2600*665*250.859.0
1260*102-1-1
420
25*85.0
307d
.1260
22
2
6
musecmmmA
mm
mkNMve
S
Bending moment Long direction
Bottom /149 5.13135010007500018.0 22min musecmmmAS
260060.25.1)(21 35.425.2 mb
Top
Bottom
Bending moment Short direction
2001 333325733665005.0
0.005 733*665*250.859.0
583.57*102-1-1
420
25*85.0
665d
6.5832
4.075.3
2
733.0
)733.0*75.3(
1560
22
2
6
2
usecmmmA
mm
M
S
Under Column A
mmmb 35005.35.1)(21' 35.462.3
mmmmb 375075.32
45.3
mmmb 144044.15.1)(21' 35.4633.0
146 6.86.8546337500018.0
633*665*250.859.0
84.6*102-1-1
420
25*85.0
665d ,633b
6.842
3.022.1
2
633.0
)633.0*22.1(
975
22min
min2
6
2
usecmmmA
mmmm
M
S
Under Column B
Shrinkage Reinforcement in short direction
/149 5.13135075010000018.0 22min musecmmmAS
mmmmb 122022.12
144.1
Reinforcement details
Example 3 (Strip footing)Design a combined footing As shown
kPamtq netall 200/20 2)( 225 mmNfc 2420 mmNf y
Dimension calculationThe base dimension to get uniform distributed load
AssumeL1=0.6 x1=5.2
m
800 kN 1280 kN
x
3040kN
A
800(0.6)+1280(5.1)+960(10.6)=3040 (x)x = 5.65m, 2(x)=11.3mL2=11.3 - (10.6)=0.7
960 kN
x2=10.7m
L2
mmmq
PA
kPamtq
netall
sg
netall
8.13.119.1610180
103040
,180/18
23
3
)(
2)(
kPaPa
A
Pq u
u 195101958.13.11
1030403.1 33
Check for punching Shearh = 700 mmd=630mm
oK 1.1457195*03.1)3.1(1280
65841000/412063012
25
4120
63040275.0
12
'2
5.32441000/41206303
2575.0
3
'
4120))400630(4
2 V kNV
kNdbf
b
dV
kNdbf
V
mmb
cU
ocs
C
oc
C
o
BExample
You can check other columns
Draw S.F.D & B.M.D Stress under footing = 195 *1.8 = 351 kN/m
3.706)1009(7.0facecolumn from at .
75.7081000/18006306
2575.0
CU
U
C
VV
kNdVMax
kNV
Check for beam shearb = 1800mm, d = 630mm
Top /229 6.33336210006300053.0
0.0053 1800*630*250.859.0
1365*102-1-1
420
25*85.0
307d ,8001b
.1366
22
2
6
musecmmmA
mmmm
mkNMve
S
Bending moment Long direction
Bottom /148 6.12126010007000018.0
1800*730*250.859.0
81*102-1-1
420
25*85.0
307d ,8001b
.7.246
22min
min2
6
musecmmmA
mmmm
mkNMve
S
Design Short direction as example 1 (lecture 11)
Reinforcement details
Mat Foundation
Check for punching Shear
Modified load
General Example, Ref. 2
General reinforcement details
