ls eccentric reversible (symmetric)
TRANSCRIPT
INPUT DATA
Size of the column (mm*mm)
Load on the column (kN)
Grade of concrete for footingGrade of steel
DESIGN CONSTANTS
DESIGN OF THE FOUNDATION
Assume weight of footing + backfill
Weight of footing + backfill (kN)
Total load (kN)
Reversible Uniaxial moment, Mux (kN-m)SBC of soil (kN/m2)
xu, max/d
Ru, lim
DESIGN OF ISOLATED FOOTINGS WITHECCENTRIC LOADING
By Limit State Method(Reversible moment acting on column)
The dimensions of the footing can be obtained by the expression
Proposed size of footing (m*m)
Provide Custom size of footing?
Custom size of footing (m*m)
DEPTH FROM BENDING MOMENT CONSIDERATION
Effective Depth (mm) proposed from Bending Moment consideration
Clear Cover Provided (mm)
Diameter (mm) of Rebar to be used in long directionDiameter (mm) of Rebar to be used in short direction
Effective Cover to the lower layer of steel (mm)Effective Cover to the upper layer of steel (mm)
Overall Depth proposed (mm)
Provide Custom Overall Depth
Custom Overall Depth (mm)
Maximum Soil Pressure, p01 (kN/m2)
Minimum Soil Pressure, p02 (kN/m2)
Pressure Intensity under the column axis, p0 (kN/m2)
Intensity of net soil pressure below the column face, p0' (kN/m2)
Maximum Bending Moment, Mx (kN/m2)
Factored Bending Moment, Mux (kN/m2)
Effective Depth for long span, dx (mm)Effective Depth for short span, dy (mm)
CHECK FOR ONE WAY SHEAR
Assume thickness (mm) at the edges of the footing
Cantilever Length to the right of the critical section (mm)
Width of footing at the top of the critical section (mm)
Assume pt % =
Tv < ks*Tc
CHECK FOR TWO WAY SHEAR
Critical Section for one way shear lies at a distance d from the column face.
Intensity of pressure p0" at the critical section (kN/m2)
Effective Depth, d' (mm)
For a balanced section, xu, max/d is equal to
For an under-reinforced section, adopt xu/d' =
xu (mm)
Width of the section at N.A., bn (mm)
Shear force Vu (kN) at the critical section
Nominal Shear Stress, Tv (N/mm2)
Tc (N/mm2)
Tv < ks*Tc
DESIGN FOR REINFORCEMENT
Design for reinforcement in the long direction
No. of bars required
Spacing (mm)
Development Length Check
Development Length required (mm)
Critical Section for Two way shear is at a distance davg/2 from the column periphery.
davg (mm)
Punching Shear, Fu (kN)
Effective Depth of the footing at the critical section, d0 (mm)
Nominal Shear Stress, Tv (N/mm2)
Permissible Shear Stress, Tc (N/mm2)
ks*Tc (N/mm2)
Mux/b1dx2 (N-mm2)
pt required
Ast1 (mm2) required
Ast1 (mm2) provided
Ld/φ for given grade of concrete and steel
Development Length available (mm)
Design for reinforcement in the short direction
No. of bars required
No. of bars required for the central band width reinforcement
Spacing (mm)
No. of bars required in each band strip
No. of bars provided in each of the outer band strips of length
Development Length Check
Development Length required (mm)Development Length available (mm)
Muy/b2dy2 (N-mm2)
pt required
Ast2 (mm2) required
Ast2 (mm2) provided
Ast2(B) (mm2) provided in central band width equal to
Remaining Area in each band strip (mm2)
Ld/φ for given grade of concrete and steel
CHECK FOR TRANSFER OF LOAD AT THE BASE
A2 (mm2)
At a rate of spread of 2:1, A1(mm2)
√(A1/A2)
Value of √(A1/A2) to be adopted
Permissible bearing stress (N/mm2)
Actual bearing stress (N/mm2)
Short Dimension Long Dimension300 500
666.66666666666780
200M20
Fe 415
0.479
2.76
10% of column load
66.67
733.34
DESIGN OF ISOLATED FOOTINGS WITHECCENTRIC LOADING
By Limit State Method(Reversible moment acting on column)
Length Breadth2.3 2.1
NO
Length Breadth2.7 2.5 Hence, OK
181.23
94.82
138.03
DEPTH FROM BENDING MOMENT CONSIDERATION
147.42
144.55
216.825
512
60
1616
6884
580
NO
450
512496
Pu/BL + Mu/BL2 ≤ qu
200
388
166.65
1324
301
0.479
0.4
120.4
1905
212.59
0.371
0.35
0.414
Hence, OK
Critical Section for one way shear lies at a distance d from the column face.
504
832.87
407
0.566
1.118
1.118
Hence, OK
2.757
0.95
1460
8
1610
281
Hence, OK
47752
davg/2 from the column periphery.
840
Hence, OK
1.931
0.61
1513
8
1609
2100 mm = 1536
8
298
Hence, OK
73
1
0.1 m = 2
47752840
Hence, OK
250000
7952400
5.64
2
18
4
Hence, OK
2.34.83
YESNO
Hence, OK
Resize the footing
20 M20 20 Fe 250 250
415 M25 25 Fe 415 415
M30 30 Fe 500 500
M35 35M40 40
201.062201.062
2.1
difference B L (L-a)/2
733.34 0 4 1.358 429200 0 3.95 1.371 435.5
0 3.9 1.385 442.50 3.85 1.398 449
0 3.8 1.412 456
0 3.75 1.426 463
Resize the footing 0 3.7 1.441 470.50 3.65 1.456 4780 3.6 1.472 4860 3.55 1.487 493.50 3.5 1.504 5020 3.45 1.52 5100 3.4 1.538 5190 3.35 1.555 527.5
0.149fckbd2
0.138fckbd2
0.133fckbd2
Area of one bar (mm2) long directionArea of one bar (mm2) short direction
0 3.3 1.573 536.50 3.25 1.592 5460 3.2 1.611 555.50 3.15 1.631 565.50 3.1 1.652 5760 3.05 1.673 586.50 3 1.694 5970 2.95 1.717 608.50 2.9 1.74 6200 2.85 1.764 632
50 6 0 2.8 1.789 644.560 8 0 2.75 1.814 657
75 10 0 2.7 1.841 670.512 0 2.65 1.868 684
16 0 2.6 1.897 698.520 0 2.55 1.926 71322 0 2.5 1.957 728.525 0 2.45 1.989 744.5
28 0 2.4 2.022 76132 0 2.35 2.057 778.5
0 2.3 2.093 796.50 2.25 2.13 815
0 2.2 2.17 835YES 580 0 2.15 2.21 855
NO 0 2.1 2.253 876.524 2.05 2.298 899
72.5 2 2.345 922.5122 1.95 2.394 947173 1.9 2.446 973
225.5 1.85 2.501 1000.5279 1.8 2.558 1029
334.5 1.75 2.619 1059.5391.5 1.7 2.683 1091.5450.5 1.65 2.751 1125.5511.5 1.6 2.823 1161.5
575 1.55 2.9 1200640.5 1.5 2.981 1240.5
709 1.45 3.068 1284780.5 1.4 3.161 1330.5855.5 1.35 3.261 1380.5934.5 1.3 3.369 1434.51017 1.25 3.484 14921105 1.2 3.61 15551198 1.15 3.746 16231297 1.1 3.894 1697
140 1403 1.05 4.056 17781517 1 4.234 1867
161
6.6348745594 Column1 Column2150 1.3175 1.25
Tv < ks*Tc Hence, OK 200 1.2
Tv > ks*Tc NOT SAFE 225 1.15250 1.1275 1.05300 1
1
1004 804
1
0.63411
Hence, OKProvide bars of less diameter
M20 2 2 Fe 250 2 3
M25 3 Fe 415 3 Fe250
M30 4 Fe 500 4 Fe415
M35 5 Fe500
M40 6
237.4766
0.44413
Hence, OK
N/A (as the footing is square). Separate dowel bars are required to transfer the load
2.98 0.2 0.531 10% of col 0.1
2.76 0.479 15% of col 0.15
2.66 0.456
(B-b)/2 min B L (L-a)/2 (B-b)/2
1850 24 2.05 2.298 728.5 110018251800 900 9001775
1750
1725
17001675165016251600157515501525
1500147514501425140013751350132513001275
12501225
12001175
1150112511001075
10501025
1000975
950925
900875850825800775750725700675650625600575550525500475450425400
375350
M20 M25 M30 M35 M40 and above
45 39 36 32 29
47 40 38 33 3057 49 45 40 36
Separate dowel bars are required to transfer the load