ANALYSIS & DESIGN OF COMBINED FOOTING
INPUT DATA : INPUT COMBINED FOOTING: CF1
fck = M 30
fy = Fe 415 CONDITION
2
SBC = 140 kN/m C5 1
Column Geometry:
C/C distance between Col's : 2.07 m
Column id: C5 C6 : LOAD CASES :
Lx = 300 375 mm X
Lz = 450 300 mm Lz
Offset from face of column : 75 mm Z
CONDITION:1
C6
C5 C6 Lz
Lx
Lx CONDITION: 2
:STAAD RESULTS : :TOTAL OF TWO COLUMNS:
Force-X Force-Y Force-Z Moment- Moment- Moment- Force-X Force-Y Force-Z Moment- Moment-Y Moment-
Node L/C
kN kN kN X kNm Y kNm Z kNm kN kN kN X kNm kNm Z kNm
C5 / 2005 5 1.652 390.714 -3.316 -2.225 0.274 -1.693 4.97 982.56 -4.49 -3.27 0.14 -4.99
6 -25.432 174.024 0.584 5.806 1.428 45.888 -59.77 772.12 0.09 6.08 2.35 106.58
7 28.325 549.132 -7.136 -10.473 -1.002 -48.87 68.35 991.39 -8.44 -12.27 -2.16 -115.25
8 0.699 430.239 -38.46 -76.252 0.357 -0.774 2.36 839.58 -58.00 -110.06 0.13 -2.49
9 2.194 292.917 31.909 71.585 0.069 -2.209 6.23 923.94 49.66 103.88 0.06 -6.18
10 -20.181 162.528 0.435 4.731 1.191 36.549 -47.28 698.34 -0.18 4.73 1.91 84.74
11 22.825 462.614 -5.741 -8.292 -0.752 -39.257 55.22 873.75 -7.00 -9.96 -1.69 -92.72
12 0.724 367.5 -30.801 -60.915 0.335 -0.78 2.43 752.30 -46.66 -88.19 0.14 -2.51
13 1.92 257.643 25.495 57.354 0.105 -1.928 5.52 819.79 39.48 82.96 0.08 -5.47
14 -26.011 29.393 1.895 6.739 1.343 46.484 -61.49 419.42 1.76 7.32 2.31 108.32
15 27.747 404.5 -5.826 -9.539 -1.087 -48.274 66.64 638.69 -6.77 -11.03 -2.20 -113.52
16 0.121 285.607 -37.15 -75.318 0.272 -0.177 0.64 486.87 -56.34 -108.83 0.10 -0.75
17 1.615 148.286 33.219 72.518 -0.016 -1.612 4.51 571.23 51.33 105.11 0.02 -4.45
C6 / 2006 5 3.314 591.844 -1.169 -1.041 -0.135 -3.295
6 -34.335 598.099 -0.49 0.277 0.922 60.696 Distance of Load C.G. from column C5 : 1.247 m
7 40.029 442.26 -1.302 -1.797 -1.157 -66.382 Area of Footing Required: 5.721 m2
8 1.659 409.338 -19.544 -33.812 -0.224 -1.713
9 4.035 631.02 17.752 32.291 -0.011 -3.972 Footing Geometry :
10 -27.095 535.811 -0.611 -0.004 0.723 48.195 Length of the footing Lx = 3.65 m
11 32.397 411.14 -1.26 -1.663 -0.94 -53.467 Width of the footing Lz = 1.8 m
12 1.701 384.803 -15.854 -27.275 -0.194 -1.732 Area of footing Provided = 6.57 m2
13 3.602 562.148 13.983 25.608 -0.023 -3.54 O.K.
3
14 -35.474 390.027 -0.132 0.581 0.969 61.833 Zxx = 1.971 m
3
15 38.89 234.188 -0.943 -1.493 -1.11 -65.245 Zzz = 3.997 m
16 0.52 201.267 -19.186 -33.508 -0.177 -0.576
17 2.896 422.948 18.111 32.596 0.036 -2.835
: SIZING CHECK :
Minimum width of
L/C Factor Req. Area P/A MX/ZX Mz/Zz P(max) P(min) P(allow) REMARKS
beam (req.) : 600. mm
5 1.5 5.15 109.67 -1.10 -0.83 111.61 107.73 140 O.K. O.K. So,
6 1.5 4.04 86.18 2.06 17.78 106.02 66.35 175 O.K. O.K.
7 1.5 5.19 110.66 -4.15 -19.22 134.03 87.28 175 O.K. O.K. Width of beam (prov.) : 600. mm
8 1.5 4.40 93.71 -37.23 -0.41 131.35 56.07 175 O.K. O.K.
9 1.5 4.84 103.13 35.13 -1.03 139.29 66.96 175 O.K. O.K. For, Slab Design :
10 1.2 4.57 97.43 2.00 17.67 117.10 77.77 175 O.K. O.K. P(max) : 166.76 kN/m2
11 1.2 5.72 121.91 -4.21 -19.33 145.45 98.37 175 O.K. O.K.
12 1.2 4.93 104.96 -37.29 -0.52 142.77 67.15 175 O.K. O.K. For, Beam Design :
13 1.2 5.37 114.38 35.08 -1.14 150.60 78.16 175 O.K. O.K. P(max) : 150.37 kN/m2
14 0.9 3.66 78.03 4.13 30.11 112.26 43.79 175 O.K. O.K. ( Considering Moment
15 0.9 5.58 118.82 -6.22 -31.56 156.59 81.04 175 O.K. O.K. along X-X axis only .)
16 0.9 4.25 90.57 -61.35 -0.21 152.13 29.02 175 O.K. O.K.
17 0.9 4.99 106.27 59.26 -1.24 166.76 45.77 175 O.K. O.K.
0.578 m 2.070 m 1.002 m
0.600 m 1.247 m 0.823 m
C5 C6 1.800 m
0.600 m
3.650 m COMBINED FOOTING: CF1
SLAB DESIGN :
Clear cantilever for slab : 0.600 m fck = M 30 Effective Depth required : 104.37 mm
Maximum Pressure @ base : 166.76 kN/m2 fy = Fe 415 Total depth required : 159.37 mm
So, Moment @ base : 30.02 kNm kmax = 0.479 So, Provide Total depth : 300 mm
Shear @ base : 50.03 kN Rmax = 0.138 Depth @ Edge : 150 mm
Factored Moment : 45.025 kNm *Dia. of bar : 10. mm Effective Depth Provided : 245 mm
Factored Shear : 75.042 kN *Clear cover : 50. mm pt required : 0.214 %
So, Ast Required : 524.81 mm2 β: 13.582 Min. pt required : 0.120 %
Provide, (*Assumed)
Dia. 10 @ 125 mm C/C Check for Shear : Acting shear stress: 0.306 N/mm2
( Ast(prov.) : 628.32 ) O.K Permissible Shear stress: 0.373 N/mm2 O.K
BEAM DESIGN :
589.29 892.65 Max. base pressure ( Pb ) = 150.37 kN/m2
UDL acting on the beam = Pb x w = 270.67 kN/m
Factored UDL (1.5X )= 406.01 kN/m
406.01 kN/m Width of beam provided = 600.00 mm
485.88 Effective depth required = 286.65 mm
234.73 Total Depth required = 374.65 mm
X = 0.873
Total Depth provided = 600.00 mm
0 0
: TOP REINFORCEMENT :
-406.77 Max. Moment = 86.97 kNm
-354.56 Effective depth provided = 559.00 mm
S.F.D. pt required : 0.131 % (assuming 25mm cover @ top)
86.97 Min. pt required : 0.205 %
So, Ast Required : 737.35 mm2
Provide,
5 Nos. - 16 Dia.
+
0 Nos. - 0 Dia.
( Ast(prov.) : 1005.31 ) O.K ( Pt(prov.): 0.300 % )
67.85 203.76 : BOTTOM REINFORCEMENT :
B.M.D. Max. Moment = 203.76 kNm
(where, X is the point of contarflexure) Effective depth provided = 512.00 mm
pt required : 0.379 %
Min. pt required : 0.205 %
So, Ast Required : 1163.81 mm2
Provide,
5 Nos. - 20 Dia.
+
0 Nos. - 0 Dia.
( Ast(prov.) : 1570.80 ) O.K ( Pt(prov.): 0.511 % )
: SHEAR REINFORCEMENT :
Maximum shear force = 485.88 kN
Max. Shear stress = 1.582 N/mm2 β: 6.812
Permissible Shear stress = 0.501 N/mm2
Section needs to be design for shear reinforcement.
Design shear force = 331.86 kN
Provide,
Nos. of Legs : 4 Dia of Stirrup ring = 8 mm
Spacing required : 112.00 mm
Spacing provided : 100 mm O.K
: SIDE FACE REINFORCEMENT : (Cl.26.5.1.3.; IS 456-2000)
Required total Ast : 0 mm2 ( Ast(prov.) : 0.00 )
Provide, 0 Nos. - 0 Dia. O.K
