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Combined Footing
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1.0 DESIGN OF COMBINED FOUNDATION
1.0 Introduction
Loads at the base of column are calculated based upon ultimate limit state and serviceability limit state.
Foundation size is decided based upon loads worked out as per serviceability limit state. It means that base
pressures are worked out at each corner of footing based upon loads derived by serviceability limit state. When
the size of the base has been determinerd from serviceability loadings, the base will then be designed using
ultimate loads
2.0 Design Data
Foundation for = C8, LIFT
Grade of concrete =
Density of concrete = t/m3
Grade of steel =
Existing GL = m
Depth of foundation below ground level = m
Founding level = m
Net SBC of strata = t/m2
Density of soil above footing = t/m3
Gross SBC of foundation strata Normal case = t/m2
Seismic case = t/m2
Wind case = t/m2
Thickness of footing at tip = m
Thickness of footing at the face of pier = m
RL of top of footing = m
C\s area of pier 1 In trans. Direction = m
In Long. Direction = m
C\s area of pier 2 In trans. Direction = m
In Long. Direction = m
C\s area of pier 1 = m2
C\s area of pier 2 = m2
In trans. Direction l = m
In Long. Direction b = m
In trans. Direction l = m
In Long. Direction b = m
Distance of column 1 centre from line 1-1 along x-x = m
2.900
3.700
Rectangle 0.400
0.700
0.280
0.600
229.345
Rectangle 2.900
3.700
10.730
M45
2.5
Fy460
3.000
231.745
0.600
20.0
1.8
20.000
25.000
25.000
228.745
Dimension of pier 1
at top of footing
Dimension of pier 2
at top of footing
0.400
0.700
1.750
centre to centre distance between columns in x-x direction = m
Distance of column 2 centre from line 1-1 along x-x = m
Distance of column 1 centre from line 2-2 along z-z = m
Distance of column 2 centre from line 2-2 along z-z = m
Offset beyond column face = m
Dimension of footing at top In trans. Direction = m
In Long. Direction = m
Dimension of footing at bottom In trans. Direction L = m
In Long. Direction B = m
3.0 Load Calculations at bottom of footing
Plan area Top = x = m2
Bottom = x = m2
Volume of footing
Uniform Portion = x ='m
3
Varying Portion = x( + ) x ='m
3
Total ='m
3
Weight of Footing = x = t
Volume of soil above footing upto ground level
= ( x ) - ( + x ) ='m
3
Weight of soil above footing upto ground level
= x 1.8 = t
Total weight of footing and soil = t
Footing and column details are as below
1 z-z (Longitudinal direction)
+ve
m col 2
m col 1 m +ve
x-x
(Transverse Direction)
2.900 m 0.400 m
2 2
1 5.800 m
66.12 119.02
176.44
3.7
00
6.6
00
0.7
00
22.968 2.5 57.42
3.00 22.968
38.280 0.6 22.968
6.6005.800
2.40 10.73 66.1238.280
5.800
5.800.000 6.600 6.60
2
6.600
5.800
6.600
2.378
6.600
2.300
0.000
22.968
38.280
38.280
4.050
4.263
0.000
5.800
col 1 col 2 Ground Level
m
0.60 m
4.0 SUMMARY OF FORCES AT COLUMN BOTTOM LEVEL UNDER SERVICEABILTY LIMIT
STATE COMBINATION & CALCULATION OF ECCENTRICITY OF LOADINGS)(Excluding foundation weight and soil above it)
4.07SERV15 1.0 D.L - 1.0 WINDx
17.0 -37.7
1154.3 4.8
-32.8
12 SERV12 1.0 D.L + 0.8 L.L + 0.8 WINDy 1708.5
1405.0
13 SERV13 1.0 D.L + 0.8 L.L - 0.8 WINDy
1273.414 SERV14 1.0 D.L + 1.0 WINDx
15
11 SERV11 1.0 D.L + 0.8 L.L - 0.8 WINDx 1326.2 -48.9-206.2
1457.7 7.5 -44.1
-56.8-148.6
-51.5
7 SERV7 1.0 D.L - 1.0 EQX 1708.9
8 SERV8 1.0 D.L + 1.0 EQy 1998.0 183.9
-41.9233.4
230.7
-35.0
4.10
1576.9
10
9 SERV9 1.0 D.L - 1.0 EQy 4.08 4.25
SERV10 1.0 D.L + 0.8 L.L + 0.8 WINDx
-46.819.7
4.08
6 SERV6 1.0 D.L + 1.0 EQX
4 SERV4 1.0 D.L + 0.8 L.L + 0.8 EQy
5 SERV5 1.0 D.L + 0.8 L.L - 0.8 EQy 1898.5
17.8 -52.8
-45.5
-51.016.6
13.4
1823.9
13.0 -53.1
1745.7
1822.4 17.6 -52.9
-55.122.3
1808.4
kN-m
P MX MZ
kN
2 SERV2 1.0 D.L + 0.8 L.L + 0.8 EQX 1515.8
1 SERV1 1.0 D.L + 1.0 L.L
LOAD COMBINATIONS
4.08 4.25
ez
4.26
4.08
3 SERV3 1.0 D.L + 0.8 L.L - 0.8 EQX
kN-m
4.08
SR. NO. ex
m
4.42
4.07 4.13
4.35
4.08 4.25
4.08 4.25
4.17
4.08
4.08
8.16
8.15
8.17
8.16
4.26
4.08 4.25
4.09
fx fz
m
4.26
4.08 4.25
4.08 4.25
m
8.51
8.50
8.16
8.51
8.51
3.0
00
8.51
8.16 8.51
8.16
8.16
m
8.52
8.84
8.15 8.25
8.70
8.34
8.16 8.50
8.17
8.16
8.52
8.16 8.50
8.15 8.20
8.16
(We require to decide the siz of footing based upon fx and fz we have for different load cases)
Footing Plan and elevation
1
2
SERV16 1.0 D.L + 1.0 WINDy16
4
4.47
#DIV/0!
1022.7 -208.9 -39.9
3
4.09 8.18 8.93
#DIV/0! #DIV/0! #DIV/0!17 SERV17 1.0 D.L - 1.0 WINDy 0.0 0.0 0.0
0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000
0.000
0.200
0.400
0.600
0.800
1.000
1.200
0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000
5.0 Check for base pressure under serviceability limit state combinations
Plan area of footing at base A = m2
ZX = x2
= m3
ZZ = x2
= m3
Base pressure at all four nodes of footing due to various load combinations is calculated.
Base pressure = P
A
SR. NO.
I+
ZL
6
6.600 5.800
6
MX
MT
2SERV2 1.0 D.L + 0.8 L.L +
0.8 EQX3280.20 -1432.88
SAFE
UNSAFE
9 SERV9 1.0 D.L - 1.0 EQy 3341.26 -1479.12 -1906.94 0.62 103.69173.9570.88
UNSAFE
8 SERV8 1.0 D.L + 1.0 EQy 3762.38 -1556.28 -2400.63 -3.55 126.20200.1270.37
UNSAFE
7 SERV7 1.0 D.L - 1.0 EQX 3473.23 -1942.76 -2078.75 -11.58 100.77193.0580.69
UNSAFE
6 SERV6 1.0 D.L + 1.0 EQX 3572.74 -1715.39 -2185.86 -6.48 111.66193.1475.00
UNSAFE
5SERV5 1.0 D.L + 0.8 L.L -
0.8 EQy3662.87 -1783.66 -2293.52 -8.65 115.31200.0376.06
UNSAFE
4SERV4 1.0 D.L + 0.8 L.L +
0.8 EQy3586.75 -1719.75 -2201.45 -6.64 112.35194.0375.05
SAFE
3SERV3 1.0 D.L + 0.8 L.L -
0.8 EQX3510.11 -1648.04 -2109.64 -4.45 109.57187.8573.82
kN-m kN-m
112.40194.1475.07
-1834.22 2.09 101.23169.2970.15
1 SERV1 1.0 D.L + 1.0 L.L 3588.23 -1720.86 -2203.00 -6.67
1 432
UNSAFE
kN/m2
kN/m2
kN/m2
kN/m2
REMARK
ZT
LOAD COMBINATIONS P
kN
I+
ML
37.004
38.280
5.800 6.600 42.108
MZ BASE PRESSURE AT
6.0 Calculation of eccentricity under loads under ultimate limit state
4.255 DCON5 1.2 D.L + 1.2 L.L + 1.2 WINDY 2659.5 34.0 -76.9 4.08
4.25
4 DCON4 1.2 D.L + 1.2 L.L - 1.2 WINDx 2186.9 21.1 -63.4 4.08 4.25
3 DCON3 1.2 D.L + 1.2 L.L + 1.2 WINDx 1519.3 13.9 -45.7 4.08
4.25
2 DCON2 1.5 D.L + 1.5 L.L 2126.3 19.3 -63.9 4.08 4.25
1 DCON1 1.5 D.L 2614.7 25.7 -75.4 4.08
ez
kN kN-m kN-m m m
MZ ex
SR. NO. LOAD COMBINATIONS
P MX
SAFE
16SERV16 1.0 D.L + 1.0
WINDy2787.06 -1402.70 -1255.82 5.56 73.4372.18 SAFE
107.06149.4158.53
140.06
15SERV15 1.0 D.L - 1.0
WINDx3169.37 -891.68 -1681.41 16.18
66.06 SAFE
-1397.44 12.31 87.84140.1864.6513SERV13 1.0 D.L + 0.8 L.L -
0.8 WINDy2918.63 -1102.06
SAFE
SAFE
14SERV14 1.0 D.L + 1.0
WINDx3037.80 -1192.33 -1539.79 9.43 92.65149.28
UNSAFE
12SERV12 1.0 D.L + 0.8 L.L +
0.8 WINDy3472.84 -1178.48 -2048.57 7.37 118.10174.0763.35
SAFE
11SERV11 1.0 D.L + 0.8 L.L -
0.8 WINDx3090.52 -1689.50 -1622.97 -3.25 84.47164.7277.00
10SERV10 1.0 D.L + 0.8 L.L +
0.8 WINDx3222.09 -1388.85 -1764.59 3.50 98.88164.8469.47
#DIV/0! #DIV/0!17SERV17 1.0 D.L - 1.0
WINDy1764.36 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
4.04
16 DCON16 1.2 D.L + 1.2 L.L - 1.2 EQx 980.0 -327.2 -43.6 4.09 4.60
15 DCON15 1.2 D.L + 1.2 L.L + 1.2 EQx 1569.1 350.0 -32.7 4.07
4.26
14 DCON14 0.9 D.L - 1.5 WINDy 1366.3 20.9 -40.2 4.08 4.25
13 DCON13 0.9 D.L + 1.5 WINDy 1182.8 2.0 -36.1 4.08
4.49
12 DCON12 0.9 D.L - 1.5 WINDx 2024.2 354.1 -46.4 4.07 4.09
11 DCON11 0.9 D.L + 1.5 WINDx 1435.2 -323.1 -57.2 4.09
4.25
10 DCON10 1.5 D.L - 1.5 WINDy 1637.9 6.1 -49.7 4.08 4.26
9 DCON9 1.5 D.L + 1.5 WINDy 1821.5 24.9 -53.8 4.08
4.40
8 DCON8 1.5 D.L - 1.5 WINDx 2862.2 363.2 -69.4 4.07 4.14
7 DCON7 1.5 D.L + 1.5 WINDx 2273.2 -314.1 -80.3 4.09
6 DCON6 1.2 D.L + 1.2 L.L - 1.2 WINDY 2475.9 15.1 -72.8 4.08 4.26
18 DCON18 1.2 D.L + 1.2 L.L - 1.2 EQy
#DIV/0!17 DCON17 1.2 D.L + 1.2 L.L + 1.2 EQy 0.0 0.0 0.0 #DIV/0!
0.0 0.0 0.0 #DIV/0! #DIV/0!
19 DCON19 1.5 D.L + 1.5 EQx 0.0 0.0 0.0
20 DCON20 1.5 D.L - 1.5 EQx 0.0 0.0 0.0 #DIV/0!
0.0 0.0 0.0 #DIV/0!
#DIV/0! #DIV/0!
#DIV/0!
#DIV/0!
22 DCON22 1.5 D.L - 1.5 EQy 0.0 0.0 0.0 #DIV/0! #DIV/0!
21 DCON21 1.5 D.L + 1.5 EQy
#DIV/0! #DIV/0!
23 DCON23 0.9 D.L + 1.5 EQx 0.0 0.0 0.0 #DIV/0! #DIV/0!
24 DCON24 0.9 D.L - 1.5 EQx 0.0 0.0 0.0
7.0 Base pressure under Ultimate limit state combinations for design of base
14DCON14 0.9 D.L - 1.5
WINDy2848.41 -1274.09 -1651.70 -0.48 60.03 149.30 88.79
13DCON13 0.9 D.L + 1.5
WINDy2664.81 -1135.02 -1432.39 3.95 57.86 135.28 81.37
12DCON12 0.9 D.L - 1.5
WINDx4035.62 -1241.10 -2420.61 10.53 69.48 200.31 141.36
11DCON11 0.9 D.L + 1.5
WINDx3446.61 -2028.39 -1764.94 -5.83 90.51 185.90 89.56
10DCON10 1.5 D.L - 1.5
WINDy3649.32 -1565.21 -1983.12 4.57 78.91 186.10
9DCON9 1.5 D.L + 1.5
WINDy3832.91 -1704.28
111.75
-2202.43 0.14 81.08 200.12 119.17
119.06 269.02
8DCON8 1.5 D.L - 1.5
WINDx5455.77 -2029.88 -3430.37 1.61 98.03 283.43
7DCON7 1.5 D.L + 1.5
WINDx4866.77 -2817.17 -2774.69 -14.75
237.32
-3157.64 -11.08 106.08 276.741 DCON1 1.5 D.L 5084.83 -2466.58
169.56
159.59
2 DCON2 1.5 D.L + 1.5 L.L 4596.38 -2009.00 -2573.03 2.83 98.25
232.84
141.90
3DCON3 1.2 D.L + 1.2 L.L +
1.2 WINDx3283.71 -1435.41 -1838.72 2.00 70.18
283.24
101.38
4DCON4 1.2 D.L + 1.2 L.L -
1.2 WINDx4304.09 -2063.70 -2641.74 -7.96 90.06
269.21
134.82
5DCON5 1.2 D.L + 1.2 L.L +
1.2 WINDY5253.07 -2493.06 -3212.18 -8.79 109.63 164.83
6DCON6 1.2 D.L + 1.2 L.L -
1.2 WINDY5069.47 -2353.99 -2992.88 -4.35 107.46 157.41
135.22
187.02
4
kN/m2
kN/m2
kN/m2
kN/m2
MX MZ BASE PRESSURE AT
kN kN-m kN-m
1 2 3
SR. NO. LOAD COMBINATIONS P
0.0 0.0 0.0 #DIV/0! #DIV/0!
26 DCON26 0.9 D.L - 1.5 EQy 0.0 0.0 0.0 #DIV/0! #DIV/0!
25 DCON25 0.9 D.L + 1.5 EQy
Maximum base pressure = 283.43 kN/m2
Minimum base pressure = -14.75 kN/m2
Assuming that this will be acting uniformly as upward pressure
Corresponding total down ward weight = 5455.77 kN
-6.45 69.46 135.09 59.18
9.92 48.43 149.49 110.98
16DCON16 1.2 D.L + 1.2 L.L -
1.2 EQx2462.11 -1598.20 -1214.21
15DCON15 1.2 D.L + 1.2 L.L
+ 1.2 EQx3051.11 -810.91 -1869.88
17DCON17 1.2 D.L + 1.2 L.L
+ 1.2 EQy1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
18DCON18 1.2 D.L + 1.2 L.L -
1.2 EQy1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
19 DCON19 1.5 D.L + 1.5 EQx 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
20 DCON20 1.5 D.L - 1.5 EQx 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
21 DCON21 1.5 D.L + 1.5 EQy 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
22 DCON22 1.5 D.L - 1.5 EQy 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
23 DCON23 0.9 D.L + 1.5 EQx 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
24 DCON24 0.9 D.L - 1.5 EQx 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
25 DCON25 0.9 D.L + 1.5 EQy 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
26 DCON26 0.9 D.L - 1.5 EQy 1482.06 #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
8.0 Average pressures to be applied in STAAD For force calculations
807.6 985.4
787.3 1037.0
520.9 785.4 986.7
536.0 738.7 892.8
574.0
1227.0
719.1 1061.5 1322.1
Mem 1 Mem 2 Mem 3
kN/m kN/m kN/m
772.2 1083.8 1320.8
734.3 1014.8 1228.2
1084.4 1476.9 1775.6
1016.2 1501.4 1870.7
1069.3 1523.7 1869.4
1031.3 1454.7 1776.8
661.1 921.2 1119.1
878.7 1252.4 1536.7
1040.0 1486.6 1826.5
925.4 1289.4 1566.3
396.21 985.40
319.64 986.67
597.38 1226.97
458.59 1322.06
381.87 892.83
646.98 1870.65
535.15 1320.80
520.82 1228.23
723.54 1869.38
709.20 1776.82
785.77 1775.55
648.45 1566.29
463.19 1119.09
594.37 1536.73
Max 1 &
2
Max 3 &
4
kN/m kN/m
700.11 1826.50
15DCON15 1.2 D.L + 1.2 L.L
+ 1.2 EQx48.43 149.49
13DCON13 0.9 D.L + 1.5
WINDy57.86 135.28
14DCON14 0.9 D.L - 1.5
WINDy60.03 149.30
11DCON11 0.9 D.L + 1.5
WINDx90.51 185.90
12DCON12 0.9 D.L - 1.5
WINDx69.48 200.31
9DCON9 1.5 D.L + 1.5
WINDy81.08 200.12
10DCON10 1.5 D.L - 1.5
WINDy78.91 186.10
7DCON7 1.5 D.L + 1.5
WINDx119.06 269.02
8DCON8 1.5 D.L - 1.5
WINDx98.03 283.43
5DCON5 1.2 D.L + 1.2 L.L +
1.2 WINDY109.63 283.24
6DCON6 1.2 D.L + 1.2 L.L -
1.2 WINDY107.46 269.21
3DCON3 1.2 D.L + 1.2 L.L +
1.2 WINDx70.18 169.56
4DCON4 1.2 D.L + 1.2 L.L -
1.2 WINDx90.06 232.84
1 DCON1 1.5 D.L 106.08 276.74
2 DCON2 1.5 D.L + 1.5 L.L 98.25 237.32
SR. NO. LOAD COMBINATIONS
Max 1 &
2
Max 3 &
4
kN/m2 kN/m2
589.1 760.9 891.6458.44 891.5716DCON16 1.2 D.L + 1.2 L.L -
1.2 EQx69.46 135.09
17DCON17 1.2 D.L + 1.2 L.L
+ 1.2 EQy#DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
18DCON18 1.2 D.L + 1.2 L.L -
1.2 EQy#DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
19 DCON19 1.5 D.L + 1.5 EQx #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
20 DCON20 1.5 D.L - 1.5 EQx #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
21 DCON21 1.5 D.L + 1.5 EQy #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
22 DCON22 1.5 D.L - 1.5 EQy #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
23 DCON23 0.9 D.L + 1.5 EQx #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
24 DCON24 0.9 D.L - 1.5 EQx #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!
#DIV/0! #DIV/0!
25 DCON25 0.9 D.L + 1.5 EQy #DIV/0! #DIV/0! #DIV/0! #DIV/0!
#DIV/0! #DIV/0!
#DIV/0! #DIV/0! #DIV/0!
26 DCON26 0.9 D.L - 1.5 EQy #DIV/0! #DIV/0! #DIV/0!
9.0 Design of Footing Slab
1) Design Formulae
The following equations are used which are based upon following modified stress block
K' = 0.156 Assuming that the redstribution does not exceed 10%
K = M
b x d2
x fcu
If K is less than or equal to K', compression reinforcement is not required.
Then;
If K is greater than K', compression reinforcement is required.
Then;
Where;
Footing dimension in longitudinal direction i.e in z-z direction = 6.600 m
width of column in longitudinal direction i.e in z-z direction = 3.700 m
1.5 x width + 3 x effective depth = 7.095 m
Footing dimension in transverse direction i.e in x-x direction = 2.900 m
(Considering width for one column as total width is shared between the two)
width of column in longitudinal direction i.e in z-z direction = 2.900 m
1.5 x width + 3 x effective width = 5.895 m
2) Design of footing in longitudinal direction at top
If the width calculated as above is greater than dimension of footing in transverse direction, we will have to provide
reinforcement spanning in longitudinal direction for total width of footing in transverse direction. If the width calculated
as above is lesser than dimension of footing in transverse direction , we need to provide two third of reinforcement
spanning In longitudinal direction in central width equal to width of column in transverse direction + three times the
effective width
If the width calculated as above is greater than dimension of footing in longitudinal direction, we will have to provide
reinforcement spanning in transverse direction for total width of footing in longitudinal direction. If the width calculated
as above is lesser than dimension of footing in longitudinal direction , we need to provide two third of reinforcement
spanning In Transverse direction in central width equal to width of column in longitudinal direction + three times the
effective width
Critical load case for maximum bending moment at top =
Design bending moment at top = kN-m
Assuming bar dia. = mm 1 nd layer
D prov. = cm
d prov = - -
= cm
K' = 0.156 Assuming that the redstribution does not exceed 10%
K = M
b x d2
x fcu
= 2540.00
6.600 x 0.265 x 45000
= 0.0322
51.50
2540
1
20
60
60 7.50
K < K'
z = 0.496 m
x = 0.043 m
As = 11722.349 mm2 = 117.223 cm2
Min Ast reqd = x x Avg. Thickness
= cm2
= cm2
Provide TOR @ mm c\c in longitudinal direction at Top
Ast prov = cm2
OK
= cm2
3) Design of footing in longitudinal direction at bottom
Critical load case for maximum bending moment at bottom =
51.48
20 150
Hence, max required steel in 117.22
6.600 m
0.13 60
138.23
660
100
138.230
Provided steel in for width of
117.22
Design bending moment at top = kN-m
Assuming bar dia. = mm 1 nd layer
D prov. = cm
d prov = - -
= cm
K' = 0.156 Assuming that the redstribution does not exceed 10%
K = M
b x d2
x fcu
= 1050.00
6.600 x 0.265 x 45000
= 0.0133
K < K'
z = 0.507 m
x = 0.017 m
As = 4736.752 mm2 = 47.368 cm2
Min Ast reqd = x x Avg. Thickness
= cm2
= cm2
Provide TOR @ mm c\c in longitudinal direction at bottom
Ast prov = cm2
OK
= cm2
Hence, max required steel in 51.48
51.50
0.13
1050
20
100
51.48
60
60 660
60
7.50 1
Provided steel in for width of 6.600 m 165.88
51.48
20 125
165.876
4) Design of footing in transverse direction
width of column in longitudinal direction i.e in z-z direction = 2.900 m
Width to be considered is minimum of the following =
1.5 x width + 3 x effective width = 5.835 m
Half the length provided in transverse direction = 2.900 m
Width for the design = 2.900 m
Maximum upward base pressure = 283.43 kN/m2
Maximum downward pressure = 46.09 kN/m2
Critical load case for maximum bending moment at top =
Resultant pressure = 237.34 kN/m2
Resultant force = 237.34 x 2.900
= 688.29 kN/m
Projection beyond face of column = 3.913 m
Design bending moment for above width = kN-m
Assuming bar dia. = mm 1 nd layer
D prov. = cm
d prov = - - -
= cm
K' = 0.156 Assuming that the redstribution does not exceed 10%
K = M
b x d2
x fcu
= 1580.00
2.900 x 0.245 x 45000
= 0.0494
K < K'
z = 0.466 m
x = 0.064 m
21
49.50
1580
20
60
60 7.50
As = 7756.373 mm2 = 77.564 cm2
Min Ast reqd = x x Avg. Thickness
= cm2
= cm2
Provide TOR @ mm c\c in transverse direction at bottom
Ast prov = cm2
OK
= cm2
5) Check for Shear
We require to check shear for the following two cases.
1) Section acting at a distance of 2 times the effective depth from the column face, if shear span is more than
4 times the effective depth. If the shear span is less than 4d, critical section for shear shall be taken at a
distance of half the shear span from the face of the column.
m m
##
##
m 1.9
9
m m
2.900 m 0.400 m
column 1 column 2
m m
##
##
##
##
0.3 2.300 m 1.55
However maximum shear force from shear force diagram (governing load case) is considered for shear design
6.6
00
3.7
00
0.13 60 290
100
22.62
Hence, max required steel in 77.56 77.56
20 100
91.106
Provided steel in for width of 2.900 m 91.11
0.7
00
= 1530 kN
width of section = 6.600 m
effective depth = 0.495 m
Shear Stress v = V
= 1530000 = mPa
x
Permissible Max Shear Stress = mPa
Hence, thickness is adequate
Provided reinforcement at section
= = cm2
% Ast at section = x = %
x
0.468
bd
495.00
0.423
5.0
10013823.008
138.230138.230
6600
Ultimate shear force at face of column/
pedestal
6600 495.00
Permissible shear stress c = mPa Table 3.8 of BS 8110 Part 1
Hence, Shear reinf is not required
6) Punching shear consideration
Section for punching shear shall be checked at a distance of 1.5 times the effective depth from the face of the
column.
Average effective depth = 51.50 + 51.50
2
= 51.5 cm
1.5 times effective depth = 0.773 m
Perimeter for column 1 = 0.528 + 0.773 + 0.000 + 0.000 + 0.773 + 0.773
= + 0.300 + 0.300 + 13.200
= 16.646 m
Perimeter for column 2 = 0.7725 + 0.773 + 0.773 + 0.773 + 0.773 + 0.773
= + 0.773 + 0.773 + 2.200
= 8.380 m
Dimension of area for punching for col 1 = 5.001 x 3.973 = 19.864 m2
Dimension of area for punching for col 2 = 2.245 x 1.945 = 4.367 m2
Ultimate shear force = 2862.16 + ( 283.43 - 46.0909 ) x 19.864
= 7576.82 kN
Shear Stress v = V
= 7576818.6 = mPa
x
Permissible Max Shear Stress = mPa
Hence, thickness is adequate from punching shear consideration
1.756
bd
0.47
5.0
8380.0 515.00
7) Concrete dimension and reinforcement details
a. Concrete dimension detailsm m
##
##
m 1.9
9
m m
2.900 m 0.400 m
column 1 column 2
m m
##
##
##
##
0.3 2.300 m 1.55
0.60 m
b. Reinforcement details
20 TOR @ 150 mm c/c
20 TOR @ 100
mm c/c
20 TOR @ 100 mm c/c 20 TOR @ 125 mm c/c
6.6
00
3.7
00
0.7
00
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 04-Jan-14
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 1.75 0 0; 3 4.05 0 0; 4 5.8 0 0;
MEMBER INCIDENCES
1 1 2; 2 2 3; 3 3 4;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 3.3545e+007
POISSON 0.17
DENSITY 25
ALPHA 1e-005
DAMP 0.05
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 3 PRIS YD 0.6 ZD 6.6
CONSTANTS
MATERIAL CONCRETE ALL
SUPPORTS
2 PINNED
3 FIXED BUT FX FZ MX MY MZ
LOAD 1 SELF WEIGHT
*Weight of soil and foundation
MEMBER LOAD
1 TO 3 UNI GY 402.6
LOAD 2 200 1.4 D.L + 1.6 L.L
MEMBER LOAD
1 TRAP GY -867.5 -1118.3
2 TRAP GY -1118.3 -1448.0
3 TRAP GY -1448.0 -1698.8
LOAD 3 203 1.4 D.L + 1.4 W.L Z+VE
MEMBER LOAD
1 TRAP GY -813.19 -1002.4
2 TRAP GY -1002.4 -1251.1
3 TRAP GY -1251.1 -1440.3
LOAD 4 207 1.0 D.L + 1.4 W.L Z+VE
MEMBER LOAD
1 TRAP GY -580.52 -715.9
2 TRAP GY -715.9 -893.9
3 TRAP GY -893.9 -1029.3
LOAD 5 211 1.2 D.L + 1.2 L.L + 1.2 W.L Z+VE
MEMBER LOAD
1 TRAP GY -738.73 -946.4
2 TRAP GY -946.4 -1219.3
3 TRAP GY -1219.3 -1426.9
LOAD 6 217 1.47 D.L + 1.1 L.L + 1.1 E.Q X+VE
MEMBER LOAD
1 TRAP GY -878.21 -1139.6
2 TRAP GY -1139.6 -1483.2
3 TRAP GY -1483.2 -1744.6
LOAD 7 218 1.47 D.L + 1.1 L.L + 1.1 E.Q X-VE
MEMBER LOAD
1 TRAP GY -904.97 -1125.0
2 TRAP GY -1125.0 -1414.2
3 TRAP GY -1414.2 -1634.3
LOAD 8 219 1.47 D.L + 1.1 L.L + 1.1 E.Q Z+VE
MEMBER LOAD
1 TRAP GY -966.55 -1169.0
2 TRAP GY -1169.0 -1435.0
3 TRAP GY -1435.0 -1637.4
LOAD 9 220 1.47 D.L + 1.1 L.L + 1.1 E.Q Z-VE
MEMBER LOAD
1 TRAP GY -816.64 -1095.7
2 TRAP GY -1095.7 -1462.4
3 TRAP GY -1462.4 -1741.5
LOAD 10 221 1.14 D.L + 1.1 E.Q X+VE
MEMBER LOAD
1 TRAP GY -649.71 -823.8
2 TRAP GY -823.8 -1052.6
3 TRAP GY -1052.6 -1226.6
LOAD 11 222 1.14 D.L + 1.1 E.Q X-VE
MEMBER LOAD
1 TRAP GY -676.47 -809.2
2 TRAP GY -809.2 -983.6
3 TRAP GY -983.6 -1116.3
LOAD 12 223 1.14 D.L + 1.1E.Q Z+VE
MEMBER LOAD
1 TRAP GY -738.04 -853.1
2 TRAP GY -853.1 -1004.4
3 TRAP GY -1004.4 -1119.5
LOAD 13 224 1.14 D.L + 1.1 E.Q Z-VE
MEMBER LOAD
1 TRAP GY -588.14 -779.9
2 TRAP GY -779.9 -1031.8
3 TRAP GY -1031.8 -1223.5
LOAD 14 225 0.84 D.L - 1.1 E.Q X+VE
MEMBER LOAD
1 TRAP GY -501.97 -594.3
2 TRAP GY -594.3 -715.7
3 TRAP GY -715.7 -808.0
LOAD 15 226 0.84 D.L - 1.1 E.Q X-VE
MEMBER LOAD
1 TRAP GY -475.36 -609
2 TRAP GY -609.0 -784.6
3 TRAP GY -784.6 918.3
LOAD 16 227 0.84 D.L - 1.1E.Q Z+VE
MEMBER LOAD
1 TRAP GY -413.64 -565.0
2 TRAP GY -565.0 -763.9
3 TRAP GY -763.9 -915.2
LOAD 17 228 0.84 D.L - 1.1 E.Q Z-VE
MEMBER LOAD
1 TRAP GY -563.55 -638.3
2 TRAP GY -638.3 -736.5
3 TRAP GY -736.5 -811.2
LOAD COMB 18 SELF WEIGHT + 200 1.4 D.L + 1.6 L.L
1 1.4 2 1.0
LOAD COMB 19 SELF WEIGHT + 203 1.4 D.L + 1.4 W.L Z+VE
1 1.4 3 1.0
LOAD COMB 20 SELF WEIGHT + 207 1.0 D.L + 1.4 W.L Z+VE
1 1.0 4 1.0
LOAD COMB 21 SELF WEIGHT + 211 1.2 D.L + 1.2 L.L + 1.2 W.L Z+VE
1 1.2 5 1.0
LOAD COMB 22 SELF WEIGHT + 217 1.47 D.L + 1.1 L.L + 1.1 E.Q X+VE
1 1.47 6 1.0
LOAD COMB 23 SELF WEIGHT + 218 1.47 D.L + 1.1 L.L + 1.1 E.Q X-VE
1 1.47 7 1.0
LOAD COMB 24 SELF WEIGHT + 219 1.47 D.L + 1.1 L.L + 1.1 E.Q Z+VE
1 1.47 8 1.0
LOAD COMB 25 SELF WEIGHT + 220 1.47 D.L + 1.1 L.L + 1.1 E.Q Z-VE
1 1.47 9 1.0
LOAD COMB 26 SELF WEIGHT + 221 1.14 D.L + 1.1 E.Q X+VE
1 1.14 10 1.0
LOAD COMB 27 SELF WEIGHT + 222 1.14 D.L + 1.1 E.Q X-VE
1 1.14 11 1.0
LOAD COMB 28 SELF WEIGHT + 223 1.14 D.L + 1.1E.Q Z+VE
1 1.14 12 1.0
LOAD COMB 29 SELF WEIGHT + 224 1.14 D.L + 1.1 E.Q Z-VE
1 1.14 13 1.0
LOAD COMB 30 SELF WEIGHT + 225 0.84 D.L - 1.1 E.Q X+VE
1 0.84 14 1.0
LOAD COMB 31 SELF WEIGHT + 226 0.84 D.L - 1.1 E.Q X-VE
1 0.84 15 1.0
LOAD COMB 32 SELF WEIGHT + 227 0.84 D.L - 1.1E.Q Z+VE
1 0.84 16 1.0
LOAD COMB 33 SELF WEIGHT + 228 0.84 D.L - 1.1 E.Q Z-VE
1 0.84 17 1.0
PERFORM ANALYSIS
FINISH
P1 COLUMN P MX MZ
SERV1 1.0 D.L + 1.0 L.L
SERV2 1.0 D.L + 0.8 L.L + 0.8 EQX
SERV3 1.0 D.L + 0.8 L.L - 0.8 EQX
SERV4 1.0 D.L + 0.8 L.L + 0.8 EQy
SERV5 1.0 D.L + 0.8 L.L - 0.8 EQy
SERV6 1.0 D.L + 1.0 EQX
SERV7 1.0 D.L - 1.0 EQX
SERV8 1.0 D.L + 1.0 EQy
SERV9 1.0 D.L - 1.0 EQy
SERV10 1.0 D.L + 0.8 L.L + 0.8 WINDx
SERV11 1.0 D.L + 0.8 L.L - 0.8 WINDx
SERV12 1.0 D.L + 0.8 L.L + 0.8 WINDy
SERV13 1.0 D.L + 0.8 L.L - 0.8 WINDy
SERV14 1.0 D.L + 1.0 WINDx
SERV15 1.0 D.L - 1.0 WINDx
SERV16 1.0 D.L + 1.0 WINDy
SERV17 1.0 D.L - 1.0 WINDy
DCON1 1.5 D.L
DCON2 1.5 D.L + 1.5 L.L
DCON3 1.2 D.L + 1.2 L.L + 1.2 WINDx
DCON4 1.2 D.L + 1.2 L.L - 1.2 WINDx
DCON5 1.2 D.L + 1.2 L.L + 1.2 WINDY
DCON6 1.2 D.L + 1.2 L.L - 1.2 WINDY
DCON7 1.5 D.L + 1.5 WINDx
DCON8 1.5 D.L - 1.5 WINDx
DCON9 1.5 D.L + 1.5 WINDy
DCON10 1.5 D.L - 1.5 WINDy
DCON11 0.9 D.L + 1.5 WINDx
DCON12 0.9 D.L - 1.5 WINDx
DCON13 0.9 D.L + 1.5 WINDy
DCON14 0.9 D.L - 1.5 WINDy
DCON15 1.2 D.L + 1.2 L.L + 1.2 EQx
DCON16 1.2 D.L + 1.2 L.L - 1.2 EQx
DCON17 1.2 D.L + 1.2 L.L + 1.2 EQy
DCON18 1.2 D.L + 1.2 L.L - 1.2 EQy
DCON19 1.5 D.L + 1.5 EQx
DCON20 1.5 D.L - 1.5 EQx
DCON21 1.5 D.L + 1.5 EQy
DCON22 1.5 D.L - 1.5 EQy
DCON23 0.9 D.L + 1.5 EQx
DCON24 0.9 D.L - 1.5 EQx
DCON25 0.9 D.L + 1.5 EQy
DCON26 0.9 D.L - 1.5 EQy
P2 COLUMN P MX MZ
100 1.0 D.L + 1.0 L.L 1823.866 17.761 -52.775
102 1.0 D.L + 1.0 W.LZ +VE 1515.838 13.435 -45.504
106 1.0 D.L +0.75 L.L + 1.0 W.LZ +VE 1745.748 16.56 -51.015
110 1.0 D.L +1.0 L.L + 1.0 W.LZ +VE 1822.385 17.602 -52.852
117 1.07 D.L + 0.75 L.L + 0.54 E.Q X+VE 1898.505 22.301 -55.121
118 1.07 D.L + 0.75 L.L + 0.54 E.Q X-VE 1808.377 13.041 -53.114
119 1.07 D.L + 0.75 L.L + 0.54 E.Q Z+VE 1708.867 -148.563 -56.778
120 1.07 D.L + 0.75 L.L + 0.54 E.Q Z-VE 1998.015 183.905 -51.456
121 1.0 D.L + 0.714 E.QX +VE 1576.903 19.717 -46.753
122 1.0 D.L + 0.714 E.QX -VE 1457.734 7.472 -44.099
123 1.0 D.L + 0.714 E.QZ +VE 1326.159 -206.204 -48.944
124 1.0 D.L + 0.714 E.QZ -VE 1708.478 233.393 -41.908
125 0.8 D.L - 0.714 E.QX +VE 1154.27 4.753 -35.014
126 0.8 D.L - 0.714 E.QX -VE 1273.439 16.998 -37.667
127 0.8 D.L - 0.714 E.QZ +VE 1405.014 230.674 -32.823
128 0.8 D.L - 0.714 E.QZ -VE 1022.696 -208.923 -39.859
200 1.4 D.L + 1.6 L.L 2614.721 25.699 -75.354
201 1.4 D.L + 1.4 W.L Z+VE 2126.272 19.299 -63.908
205 1.0 D.L + 1.4 W.L Z+VE 1519.345 13.861 -45.738
210 1.2 D.L + 1.2 L.L + 1.2 W.L Z+VE 2186.862 21.122 -63.423
217 1.47 D.L + 1.1 L.L + 1.1 E.Q X+VE 2659.457 33.999 -76.904
218 1.47 D.L + 1.1 L.L + 1.1 E.Q X-VE 2475.864 15.135 -72.816
219 1.47 D.L + 1.1 L.L + 1.1 E.Q Z+VE 2273.157 -314.058 -80.28
220 1.47 D.L + 1.1 L.L + 1.1 E.Q Z-VE 2862.163 363.192 -69.439
221 1.14 D.L + 1.1 E.Q X+VE 1821.54 24.93 -53.829
222 1.14 D.L + 1.1 E.Q X-VE 1637.946 6.066 -49.742
223 1.14 D.L + 1.1E.Q Z+VE 1435.24 -323.128 -57.206
224 1.14 D.L + 1.1 E.Q Z-VE 2024.246 354.123 -46.365
225 0.84 D.L - 1.1 E.Q X+VE 1182.751 1.987 -36.114
226 0.84 D.L - 1.1 E.Q X-VE 1366.344 20.851 -40.202
227 0.84 D.L - 1.1E.Q Z+VE 1569.05 350.045 -32.738
228 0.84 D.L - 1.1 E.Q Z-VE 980.045 -327.206 -43.578
815.5 191.3 191.7
861.2 209.1 223.6
860.1 237.9 262.1
906.8 239.5 37.7 Node Horizontal
951.4 278.0 45.3 L/C Fx kN
769.9 0.0 0.0 1 21.022
769.9 0.0 0.0 11.309
805.6 217.3 149.8 13.365
841.2 261.1 174.8 14.051
851.5 314.8 237.2 -2.715
876.9 317.4 74.9 45.947
887.2 371.1 87.6 -2.302
769.9 0.0 0.0 45.535
769.9 0.0 0.0 -13.891
802.0 446 1089.3 50.451
802.0 446.3 -1012.6 -13.346
802.0 -450.1 1089.3 49.905
802.0 -450.1 -1012.6 46.795
811.2 445.9 1112.2 -17.547
811.2 445.9 -1022.7 46.249
811.2 -453.7 1112.2 -17.002
811.2 -453.7 -1022.7
811.0 489.8 1119.5
811.0 489.8 -1014.6 Node Horizontal
811.0 -491.7 1119.5 L/C Fx kN
811.0 -491.7 -1014.6 1 29.98
820.3 458.1 1091.5 15.832
820.3 458.1 -1076.4 8.52
820.3 -469.8 1091.5 15.467
820.3 -469.8 -1076.4 -19.675
829.2 500.1 1092.6 79.451
829.2 500.1 -1074.5 -18.835
829.2 -509.7 1092.6 78.611
829.2 -509.7 -1074.5 -28.724
792.9 273.1 1034.5 70.402
792.9 273.1 -1034.5 -27.884
792.9 -273.1 1034.5 69.562
792.9 -273.1 -1034.5 64.918
792.9 273.1 1034.5 -34.208
792.9 273.1 -1034.5 64.078
792.9 -273.1 1034.5 -33.368
792.9 -273.1 -1034.5
802.0 928.4 353.6
802.0 928.4 -277.0
802.0 -932.3 353.6
802.0 -932.3 -277.0
811.2 926.4 365.0
811.2 926.4 -275.5
811.2 -934.2 365.0
811.2 -934.2 -275.5
811.0 945.5 372.5
811.0 945.5 -267.7
811.0 -947.4 372.5
811.0 -947.4 -267.7
820.3 929.5 332.7
820.3 929.5 -317.6
820.3 -941.2 332.7
820.3 -941.2 -317.6
829.2 946.6 334.1
829.2 946.6 -316.0
829.2 -956.3 334.1
829.2 -956.3 -316.0
792.9 910.3 310.3
792.9 910.3 -310.3
792.9 -910.3 310.3
792.9 -910.3 -310.3
792.9 910.3 310.3
792.9 910.3 -310.3
792.9 -910.3 310.3
792.9 -910.3 -310.3
800.0 455.3 1077.3
800.0 455.3 -1017.4
800.0 -375.3 947.3
800.0 -375.3 -887.4
807.2 464.1 1095.2
807.2 464.1 -1025.3
807.2 -435.5 1095.2
807.2 -435.5 -1025.3
809.2 507.1 1111.4
809.2 507.1 -1016.5
809.2 -474.4 1111.4
809.2 -474.4 -1016.5
814.3 485.4 1088.1
814.3 485.4 -1058.1
814.3 -442.6 1088.1
814.3 -442.6 -1058.1
816.4 528.4 1094.3
816.4 528.4 -1059.3
816.4 -481.4 1094.3
816.4 -481.4 -1059.3
792.9 273.1 1034.5
792.9 273.1 -1034.5
792.9 -273.1 1034.5
792.9 -273.1 -1034.5
792.9 273.1 1034.5
792.9 273.1 -1034.5
792.9 -273.1 1034.5
792.9 -273.1 -1034.5
800.0 937.5 344.2
800.0 937.5 -284.2
800.0 -923.2 344.2
800.0 -923.2 -284.2
807.2 944.6 353.0
807.2 944.6 -283.1
807.2 -916.1 353.0
807.2 -916.1 -283.1
809.2 962.8 366.6
809.2 962.8 -271.8
809.2 -930.1 366.6
809.2 -930.1 -271.8
814.3 956.7 336.9
814.3 956.7 -307.0
814.3 -913.9 336.9
814.3 -913.9 -307.0
816.4 974.9 340.6
816.4 974.9 -305.5
816.4 -928.0 340.6
816.4 -928.0 -305.5
792.9 910.3 310.3
792.9 910.3 -310.3
792.9 -910.3 310.3
792.9 -910.3 -310.3
792.9 910.3 310.3
792.9 910.3 -310.3
792.9 -910.3 310.3
792.9 -910.3 -310.3
991.7 259.3 321.3
769.1 212.8 467.7
533.6 419.7 216.6
544.4 455.6 584.0
515.9 452.7 201.0
515.6 308.2 141.1
462.6 273.5 463.0
508.8 382.5 138.9
Vertical Horizontal Moment
Fy kN Fz kN Mx kNm My kNm Mz kNm
5.036 -0.008
-7.138 0.094
-6.251 0.091
-5.956 0.09
9.754 -0.123
0.267 0.108
-19.907 0.328
29.928 -0.343
10.127 -0.157
-2.417 0.149
-29.092 0.439
36.801 -0.448
-3.188 0.15
9.356 -0.156
36.03 -0.447
-29.863 0.44
Vertical Horizontal Moment
Fy kN Fz kN Mx kNm My kNm Mz kNm
7.287 -0.012
-9.993 0.131
-11.534 0.133
-9.345 0.127
16.629 -0.246
-2.697 0.225
-43.792 0.673
57.724 -0.694
14.057 -0.24
-5.269 0.231
-46.364 0.679
55.152 -0.688
-6.425 0.232
12.901 -0.239
53.996 -0.687
-47.52 0.68
