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Author: Mr. S. Manikandan M.E., M.I.S.T.E. Assistant Professor & Head (i/c), Department of Civil Engineering, Shanmuganathan Engineering College, Arasampatti, Pudukkottai - 622507. E-M…Full description
SEMINAR REPORT OF DESIGN OF ISOLATED & COMBINED FOOTING
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Design of eccentric loaded column using Tedds. Procedure results.
Isolated Footing by Limit State Method Data Required/assumed Required/assumed Safe Bearing Capacity of the soil M20 f ck FE415 Fe Depth of soil above footing Provide Overal Depth of footing d Min Eff. depth required Footing dimensions B L Column dimensions a b Load from Column Net soil reaction B. M. at the face of column x = 0.5 Mxx y = 0.5 Myy
= = = = = = =
50 25 415 1.1 350 300 50
KN/m2 N/mm2 N/mm2 m mm mm mm
P = Mx = My = Zx = Zy = net soil reaction = net soil reaction =
87 0 0 0.56 0.56 38.67
Kn Kn-m Kn-m m3 m3 KN/m2
38.666667
Considering only loads = = = = = = = = =
1.5 m 1.5 m 500 500 87 38.67
mm mm KN KN/m2
7.250 KN-m/m length 7.250 KN-m/m length
Xumax = Mulimit =
144 mm 310.42 310.42 Kn-m Kn-m Mulimit>M, Hence Section is Under reinforced Designing as Under reinforced section xu=0.87.fy.Ast/0.36.fck.b Astx = 67.22 mm2 Asty = 67.22 mm2 Ast min = 420 mm2 Provide Astx 10 mm bar @ 180 mm C/C Provide Asty 10 mm bar @ 180 mm C/C 420. 420.00 00 mm2 mm2
Astlimit=
3589.5 3589.53 3 mm2 mm2
AstxW.S.M
77.8 77.83 3 mm2 mm2 44.4E+ 44.4E+6 6 KN-M KN-M
Check for One Way Shear Factored Shear
420.00 Vu = 11.60 KN Tv = 0.039 p= 0.140 Tc = 0.282 From Code Using formula Tv
Check for Two Way Shear Two way shear = T vv = Allowable shear = Tvv < Tcc hence safe
93.38 0.097 1.250
Check for bearing Bearing stress at the contact of column and footing = Axial load/area of column = 0.35 N/mm2 Permissible Bending Stress = 22.50 N/mm2 Bearing stress calculated < permissible bearing stress hence No Dowel to be used
Isolated Footing by Limit State Method Data Required/assumed Safe Bearing Capacity of the soil M20 FE415 Depth of soil above footing Provide Overal Depth of footing
(To b Modify)
f ck Fe D
= = = = =
90 20 415 1.5 500
KN K N/m2 N/mm2 N/mm2 m mm
=
mm mm mm m m
d T L B
= =
442 250 3.1 3.1
a b
= =
300 mm 500 mm
Load from Column Net soil reaction B. M. at the face of column Mxx Myy dxxreq dyyreq Designing as Under reinforced section xu=0.87.fy.Ast/0.36.fck.b Astx Asty Ast min
= = = = = =
Footing dimensions Column dimensions
P Mx MZ Zx Zz
= = = = =
σ
40 10 15 4.97 4.97 9.20
Net soil reaction =
4.16
Astlimit
=
4230.86
AstxW.S.M
= =
184.04 152.0E+6
M.R
CALCULATIONS
Provide Astx 1000.00 Provide Asty 1000.00 Check for One Way Shear Factored Shear Vu = Tv = Tc = Check for Two Way Shear Two way shear = T vv = Allowable shear =
m m2 m m2
40 9.20 25.26 30.20 95.66 104.60
= 159.55 = 191.02 = 1000 16 mm tor @ 16 mm tor @
KN KN/m2 KN-m/m length KN-m/m length mm mm mm
mm2 mm2 mm2 200 mm C/C 200 mm C/C
11.84 KN KN 0.027 p= 0.226 0.344 From Code Using formula Tv
Check for bearing Bearing stress at the contact of column = 0.27 N/mm2 and footing = Axial load/area of column column = Permissible Bending Stress = 18.00 N/mm2 Bearing stress calculated < permissible bearing stress hence No Dowel to be used
16.84
Kn Kn-m Kn-m m3 m3 KN/m2 KN/m2
mm2 mm2 KN-M
Combined Footing by Limit State Method Safe Bearing Capacity of the soil = M20 fck = Fe415 Fe = Provide Overal Depth of footing D = d = Depth above footing = Footing dimensions B = L = Column dimensions a1 = a2 = b1 = b2 = Net soil reaction = UDL for long. BM= R.B UDL for Trans. BM=R.1 Longitudinal BMD M1= w.s1 /2 M1 = M2=w.s2 /2 M2 = Xumax =
Design of shear Critical section 1 x1=s1+b1+d V1 Tv Tc Critical section 2 x2=s2+b2+d V2 Tv Critical section 3 x3=s2-d2 V3 Tv Tc
= = = =
1.74 126.68 0.1152 0.2751
= = =
-0.1691 131.42 0.1195
= = = =
1.6491 306.43 0.2786 0.3716
1493.2
16 ф @200 C/C Min.Steel 16 ф @200 C/C > Astmin
Two Way Shear (Punching) Under column 1 Tvv 0.2166 p = 0.1358 Tcc 1.1180 Tvv < Tcc hence safe Tv
COMBINED FOOTING
DESIGN BY SURAJ
COMBINED FOOTING
DESIGN BY SURAJ
xW1
d
s1
W1+W2 W2
c
d
Ast
ast1
88.99445
d2
ast2 Transeverse steel
c
a2 s2
c
a2 s2
Top level steel t1
t2
Bottom level steel
Ast2 AstT1
Ast1 Ast
COMBINED FOOTING
DESIGN BY SURAJ
0.287509
0.15
COMBINED FOOTING
DESIGN BY SURAJ
COMBINED FOOTING
DESIGN BY SURAJ
COMBINED FOOTING
DESIGN BY SURAJ
Combined Footing Using Limit State Method Data Required/assumed Safe Bearing Capacity of the soil M20 fck FE415 Fe Provide Overal Depth of footing d Depth above footing Footing dimensions B L Column dimensions b1 b2 l1 l2 Net soil reaction UDL for long. BM= R.B UDL for Trans. BM=R.1
Longitudinal BMD
2
M1= w.s1 /2
= = = = = =
90 20 415 600 540 2.5
= =
3 m 18.3 m
= = = = =
700 700 700 700 66.91 301.10 100.37
KN/m2 N/mm2 N/mm2 mm mm m
mm mm mm mm KN/m2 KN/m2 KN/m2
199.10 KN-m
W1 W2 W3 Mx1 Mx2 Mx3 Mz1 Mz2 Mz3 Af a1 c1 c2 xL B a2 s1 s2 Zx Zz
Design of shear Critical section 1 x1=s1+b1+d = 2.39 V1 = 80.36 Tv = 0.0496 Tc = 0.2090 Tv
p = 0.074074
x2=s2+b2+d = 4.3057303 V2 = 113.53 Tv = 0.0701 Tv
p = 0.982593
Two Way Shear (Punching) Under column 1 Tvv = Tcc = Tvv < Tcc hence safe
0.2603 1.1180
Under column 2 Tvv = Tvv < Tcc hence safe
0.4880
Transeverse shear Vt= R.(t1-dt) = 40.82 KN Tv = 0.08 Tc = 0.3974 Tv
pt =
0.3175
xW1
c
d
s1
W1+W2
W2
d
Ast
ast1
d2
ast2 Transeverse steel
a2
c
s2
944.1 51.225 240.435 69.2246812 15
c
a2 s2
t1
t2
Top lev
ф @260 C/C ф @10 C/C ф @260 C/C
Bottom ф @260 C/C ф @260 C/C `
Ast2 AstT1
Ast1 Ast
el steel
level steel
Combined Footing by Limit State Method (beam slab) Data Required Safe Bearing Capacity of the soil M20 fck FE415 Fe Width of beam b Column dimensions b1 b2 l1 l2
= = = = = = = =
Footing dimensions B = L = Size is adequate w.r.t S.B.C Net soil reaction = UDL for long. BM= R.B UDL for Trans. BM=R.1
Af xL 1.7 m B 7m a2 s1 136.36 KN/m2 s2 228.57 KN/m2 Zx 136.36 KN/m2 Zz
Slab is designed to resist transeverse bending Transeverse steel t1 = 0.638 Mt1 41.64 t2 = 0.638 Mt2 41.64 d Reqd = = 136.96 Provide Overal Depth of footing D = 190 d = 144 Xumax = 76.32 Mulimit = 46.14 Transverse steel AstT1 = 1482 AstT2 = 1482 Astmin = 285 Provide Distribution steel of Astmin 8 mm bar @ Design of beam Longitudinal BMD
KN/m2 N/mm2 N/mm2 mm mm mm mm mm
802 mm2 2692 mm2 2692 mm2
KN KN KN-m KN-m m m m
11.73 mm2 2.1 m 7 m 1.7 m 1.4 m 1.2 m 1.2 m 3.28 mm3 13.69 mm3
M Astmin > Astmin mm C /C
b = 400 d = 534 D = 590
> Astmin > Astmin
x= 3.5 Mx = 280.00 KN-m Top steel is to resist BM of 280.00 KN-m as inverted T-beam Action Lo = 3.13 m bf = 0.934 m Mulimit = 592.27 Kn-m M Mx: Section is safe under Bending Design of shear
Critical section 1 x1=s1+b1+d V1 Tv Tc Providing 2-legged Critical section 2 x2=s2+b2+d V2 Tv Providing 2-legged Critical section 3 x3=s2-d2 V3 Tv Tc Providing 2-legged
0.666 152.23 0.1701 0.2033 Tv
Min. spacing is lesser of following a. Asv/b.Sv=0.4/fy b. 0.75*d c. 450mm d. 0.87.fy.Asv.d/(Tv-Tc)b.d if Tv>Tc
`
Strap Footing: +
L2
Data Required Safe Bearing Capacity of the soil
SBC
=
150 KN/m2
Allowable stress in Concrete M20 Allowable stress in steel Fe 415 Width of beam
fck Fy b
= = =
15 N/mm2 415 N/mm2 400 mm
Column sizes
b1 b2 b3
= = =
300 mm 400 mm 0 mm
Loads from columns
W1 W2 W3
= = =
600 KN 900 KN 0 KN
L1 a1 c
= = =
3 m 0.15 m 5 m
Area of footing CG of fooing Footing dimensions
Af xL2 B a2 Gap s1 s2
= = = = = = = =
11.00 2 2.475 2.0 1.2375 0.9125 0 1.0375
Net soil reaction UDL for long. BM= R.B
R wLong
= =
136.36 KN/m2 273.97 KN/m2
UDL for Trans. BM=R.1
wTrans
=
136.36 KN/m2
x Mmax Dreq
= = =
0.80 m 66.20 KN-m 230 mm
Distance bet columns
m2 m m m m m m m
Design of Cantilever Slab Cantilever projection Max. Bm in Slab
d xumax
= =
184 mm 121.92 mm
Mulimit
= =
167.23 KN-m 1222 mm2
Ast
M
Check for shear V = 126.93 KN Tv = 0.69 KN/m2 Tc = 0.52 pt = 0.66 Tv>Tc, Design of shear is reqd., Increase Depth of footing to, d = 254 Provide Overal depth of footing 300 mm Ast = 791 mm2 12 mm bar @ 90 Astmin = 360 mm2 8 mm bar @ 130 Design of Beam Max BM BM at end of footing BM corresponding to s2 BM at the end of right side footing
Depth req. as per T-beam action Depth req. as/ rect. beam action Provide overall depth of steel
Mmax M M2 M Mulimit
= = = = =
d d D
= = =
Area of steel Top steel in beam
Ast Astmin Provide 12 Nos steel at bottom Ast Provide 4 Nos Check for moment of resitance MR Astside Area of side face steel Provide 3 Nos
= = 20 = 20 = = 10
850.50 715.68 221.18 411.93 715.95
KN-m KN-m KN-m KN-m KN-m
x= x= x= x= xumax =
2.19 L1 =3 5.35 3.9125 446.4
930 mm 1000 mm
3388 mm2 762 mm2 TOR in two row, total Ast= 3770 mm2 762 mm2 TOR total ast= 1257 mm2 IF((0.87*E17*I53/(0.36*E16*F4 bf= Lo/(Lo/b+4)+bw 400 mm2 TOR bar in each face BUT spacing<30mm
Design for shear V1 Tv Tc
= = =
m m m m
517.685 KN 1.39163 0.6581
x1
930.3
p x2
1.4
G1
m mm C/C As main steel mm C/C as distribution
Isolated Circular Footing by Limit State Method Data Required/assumed Safe Bearing Capacity of the soil M20 FE415 Depth of soil above footing Provide Overal Depth of footin
fck Fe h D deff
= = =
80 KN/m2 20 N/mm2 415 N/mm2
= = =
1.5 m 700 mm 642 mm
Cons loads only σ M.R =
300 mm
Astlimit
T Diameter of footing Column dimensions CALCULATIONS
D d side Load from Column Upword soil pressure at face of column B. M. at the face of column x Mxx dxxreq
= = = = = = = =
Ast Ast min
= =
Provide Check for One Way Shear Factored Shear Vu = Tv = Tc = Check for Two Way Shear Two way shear = Tvv = Allowable shear =
16 Nos
3.75 3.5 2.47 517.4 214.02 1.12 240.19 187.71
P = Mx = Zx =
51.68
σ
=
AstxW.S.M = m mm m Tv>Tc Unsafe KN KN m KN-m mm
1046.18 mm 3150 mm
517.4 25 5.18 46.85
654.70 6145.28 1807.40
2
16 mm tor in each direction at right angles to each oth
755.18 KN 0.291 p= 0.131 0.271 From Code Using formula Tv>Tc Unsafe 830.734 KN 0.638 1.118 Tvv < Tcc hence safe
Kn Kn-m m3 KN/m2 KN/m2
KN-M mm mm Data req for WSM j 0.9 st 230 cbc 7 m 13.33 x1 0.29 j 0.90 Q %steel er