REVISION INDEX:-

DESIGN OF ISOLATED FOOTINGFoundation Committee members

Sl.No Rev.No Prepared Checked Approved Remarks K. Chandra SekharanBy Date By Date By Date P. Balachandran

1 0 PGL PBC KCS S. VidhyadaranD. JacobP. Gajalakshmi

DESIGN OF ISOLATED FOOTING WITH BIAXIAL ECCENTRICITY:-

1.0 HOW TO USE THIS WORK SHEET

Step 1 Read this page carefully and completely.

Step 2 In case of any doubts / discrepancies, contact : Foundation committee members

Step 3 Identify carefully the coordinate directions for the foundations with respect to

the cardinal (geographical) directions

Step 4 Enter all basic input datas required for the foundation design into tab "USER

INTERFACE"

Step The user can take the advice of the lead engineer for the allowable bearing pressure

ratio and allowable percentage of contact length.

Step 5 Copy the applicable support reactions from STAAD output into tab "STAAD

OUTPUT(UNFACT) & STAAD OUTPUT(FACT)"

The worksheet will convert the support reactions to actions as per

(FOUNDATION 3D) COORDINATE SYSTEM (see 2.2 below)

Step 6 Enter the bearing capacity factor and the load case number into tab "SUMMARY-SBC"

These factors are the only manual inputs in the tab "SUMMARY-SBC". Table function

is used to perform repetitive calculation for various inputs at one shot. This function is

available under tools menu. The results of reference calculations are kept at the row

above the table function starts, which is linked from the sheet "SBC- SAMPLE

CALCULATION". Everything is linked through the "Column input cell" in table function.

Whatever the formulae used to calculate the X & Y direction forces , is performed for all

other rows (with in the Table array) by reading the corresponding input forces(ouside

the Table array). Attention : Before editing or customizing this Table function, kindly,

get the proper knowledge base from the experts.

Step 7 The tab "SBC-SAMPLE CALCULATIONS" is a locked worksheet where all the sample

calculations for the SBC calculation,stability and sliding check are carried out step by

step.All the inputs required for the calculations are taken from the tab"USER

INTERFACE" and from "SUMMARY-SBC".

Step 8 Enter the Dead Load factor and the load case number into tab "SUMMARY-DSN

VALUES" These are the only manual inputs in the tab "SUMMARY-DSN

VALUES". Table function is used to perform repetitive calculation for various inputs at

one shot. Kindly go through the Step 6 mentioned above to know about the Table

function.

Step 9 The tab "DSN VALUES-SAMPLE CALCULATIONS" is a locked worksheet where all

the sample calculations for the design moment,one way shear and punching shear are

carried out step by step.All the inputs required for the calculations are taken from the

tab"USER INTERFACE" and from "SUMMARY-DSN VALUES".

Step 10 Based on the design standard ,the sheet is selected for the footing design

Step 11 Tab "DSN BS8110" will give the footing design done as per british standard.

The user has to cross check the maximum value taken for the design calculation

with the maximum value in the tab"SUMMARY-DSN VALUES"

Step 12 The above mentioned check has to be done in the tab "DSN IS456" also.

Step 13 While doing the documentation, the user has to submit the following sheets

a)USER INTERFACE(optional)

b)SUMMARY-SBC

c)SBC-SAMPLE CALCULATIONS

d)SUMMARY-DSN VALUES

e)DSN VALUES-SAMPLE CALCULATIONS

f)DSN-BS8110/DSN-IS456(Based on the selected design standard)

2.0 DESIGN PROCEDURE USED IN THIS WORKSHEET

2.1

2.2 The following Foundation-3D co-ordinate system is be adopted for loads and basic input datas..

All basic input datas except factored and unfactored loads shall be entered in the worksheet USER

INTERFACE in magenta color

Conversion of Staad Co-ordinates to Foundation-3D coordinates

Multiply By WorksheetStaad

ReactionMultiply

ByStaad Action

Fx -1 (-)Fx - (-)Fx

Fy -1 (-)Fy -1 Fy

Fz -1 (-)Fz -1 Fz

Mx -1 (-)Mx -1 Mx

Mz -1 (-)Mz -1 Mz

2.4 SBC & Stability Calculations:-

2.4.1 Max Bearing Pressure is calculated using the Teng chart (see tab : "Teng Chart")

& Partial Contact conditions

2.4.2 Calculated max bearing pressure for each loadcase is checked against Gross Bearing

2.4.3 Stability ratio is calculated as the ratio of the resisting moment (Pv x L/2 or B/2) to the

overturning moment in each direction (i.e., the moment at the bottom of foundation,Mxx or

2.4.4

each direction and it is checked with the allowable sliding ratio

2.4.5 The calculated stability ratio and sliding ratio more than 100 is taken as 100.

2.4.6 The contact length along X and Y direction is calculated using Teng's Chart

3.0 DESIGN CALCULATIONS (STRESSES & REBAR)

3.1 The design calculations can be done with either IS 456-2000and BS 8110-2000

(ACI 318 to be implemented)

3.2 The design forces acting at bottom of foundation is calculated for each load case.

3.3 Since the dia of bar to be placed in each direction is not known intially, the effective depth of

footing is calculated as follows,

Overall depth - clear cover - Bar dia in X-Dirn - Bar dia in Z-Dirn/2

3.4 Both moment and beam shear is calculated based on the assumption that the max bearing

Note:-Using Teng chart, max bearing pressure can be calculated for both Full contact

Capacity of soil(see Additional Note 1 below)

Mzz) and it is checked with the allowable stability ratio specified by the user (see Additional Note 2)

Sliding ratio is calculated as the ratio of the resisting force ie., m x Pv.to the lateral force in

Note:- The resisting lateral force is calculated based on the Friction coeffcient between

the soil and concrete.Passive resistance of soil is not considered here. (see Additional Note 3)

Note:-Max bar dia is taken for effective depth calculation in both direction

pressure(Pmax) calculated for factored loads is acting uniformly under the bottom of

Actual Adopted

moment and shear calculations,the following worksheet can be used(Foundation-3D validation.xls)

3.5 The base slab is designed for the max design moment at the face of the pedestal / column in both directions

3.6 The depth of footing is checked for one way shear acting at 'd' distance and '2d' distance from the face

of pedestal in both direction

3.7 The one way shear at 'd' distance and '2d' distance is checked with Enhanced Shear Strength and

Actual Shear Strength respectively.

3.8 The depth of footing is also checked for two way shear at the face, 0.75d from the face of

pedestal and 1.5d from the face of pedestal.

3.9 The punching shear force calculation is as per cl.3.7.6 of BS8110 i.e., considering the effect

of moment in each direction independently.

shear calculation as per BS is followed in both IS and BS designs.

case a: Effective shear force for internal column

foundation as shown in fig 2. (see Additional Note 4)

Note:- If the user want to do accurate calculations,i.e., considering the variation of pressure in the

(see also Additional Note 5)

Note:- If the user do not want to use the Enhanced shear strength in one way shear check, then he has

to enter the word " Not Used" in the User Interface Sheet.

Note:-Since the additional shear developed due to the moment is taken care in the BS code , Punching

Pmax Pmin

Fig.1

Pmax

Fig.2

case b: Effective shear force for corner column

Veff = 1.25Vt

case c: Effective shear force for edge column

Where

Vt - design shear transferred to the column

x - the length of the side of the perimeter

considered parallel to the axis of bending

Mt - is the design moment transmitted from the

column to the footing at the connection

Note:-

a) From the above three cases ,'case a' is used in this worksheet

b) The effective shear force is calculated in each direction independently .

4.0 Top Reinforcement is provided as per the following criteria:-

Case a: Depth of footing less than or equal to 600mm

Tension Max(Percentage of reinforcement required for factored

downward Pressure,Minimum Percentage of reinforcement)

Compression No Top Reinforcement required

Case b: Depth of footing more than 600mm

Tension Max(Percentage of reinforcement required for factored

downward Pressure,Minimum Percentage of reinforcement)

Veff = Vt(1+1.5Mt/Vtx)

Veff = Vt(1.25+1.5Mt/Vtx)

Compression 0.5 times the Minimum Percentage of reinforcement

Additional Notes:-

1 Use net bearing capacity if the footing is just below a basement raft : ie additional bearing

capacity due to overburden will not be available.

2 Refer project DBR for the allowable FOS for stability. Code specified values may be used

where DBR does not specify these.

3 Passive resistance from soil shall be considered only with the specific permission of the

Lead Engineer and if and where permitted by the Project DBR

4 A uniform pressure is used for strength design for the following reasons :

a In many cases we do not know the final loads of equipment etc at the time

the foundation design is completed. A conservative approach is essential.

b Soil conditions vary over site / sites. The pressure distribution under the

footing would vary depending on the type of soil, rigidity of footing etc

Many of these factors are not taken into account in normal design office

environment.

5 "More accurate" approach shall only be used for checking adequacy in case of shorfall by

the "uniform" pressure approach of this worksheet

ISOLATED FOOTING - SAMPLE CALCULATION

Footing Mark F1 NODE: 1, 3, 8 & 10

Design StandardIS456-2000 2

BS8110-1997

INPUT DATA:- RESULTS:-

Project Dirn. E-W N-S VERT Actual Allowable Utilization Ratio Remarks

Fdn 3D direction X Z Y BEARING PRESSURE #REF! #REF! #REF! #REF!

Pedestal Size(mm) 300 300 1000CONTACT LENGTH

X-Direction #REF! 60% - #REF!

Footing Size(mm) 1300 1300 300 Z-Direction #REF! 60% - #REF!

Eccentricity,e(mm) 0 0 -STABILITY

X-Direction #REF! 1.50 - #REF!

Z-Direction #REF! 1.50 - #REF!

Bottom of Foundation below FFL = (-)1.30 mSLIDING

X-Direction #REF! 1.50 - #REF!

Net Safe Bearing Capactity = 150 Z-Direction #REF! 1.50 - #REF!

Depth of Foundation below FGL dfgl = 1.00 m Required Provided

% %

= 0.00 m Governing L/C #REF!

Grade slab thickness = 0.00 mm X-Direction #REF! #REF! #REF! #REF! #REF! #REF!

Live load on grade slab LL = 0.00 Governing L/C #REF!

Unit Weight of soil = 18.00 Z-Direction #REF! #REF! #REF! #REF! #REF! #REF!

Increament of Bearing Pressure for X-Direction #REF! #REF! #REF! #REF! #REF! #REF!

non-permanent loads = 33.33 % Z-Direction #REF! #REF! #REF! #REF! #REF! #REF!

Angle of internal friction f = 35 degree

m = 0.47 Governing L/C #REF!

Allowable FOS against Overturning = 1.50 X-Direction #REF! #REF! #REF! #REF!

Allowable FOS against sliding = 1.50 Governing L/C #REF!

Maximum Teng value k = #REF! Z-Direction #REF! #REF! #REF! #REF!

ex/L = #REF! Governing L/C #REF!

ez/B = #REF! X-Direction #REF! #REF! #REF! #REF!

ex = #REF! Governing L/C #REF!

ez = #REF! Z-Direction #REF! #REF! #REF! #REF!

At face #REF! #REF! #REF! #REF!

Load acting at(Top of Pedestal/Bottom of Footing): TOP OF PEDESTAL 2 At 0.75d #REF! #REF! #REF! #REF!

BOTTOM OF FOOTING At 1.5d #REF! #REF! #REF! #REF!

Characteristic strength of concrete fck = 25

kN/m2

Depth of foundation from the level of point of application of forces (for pedestals only)

mm2 mm2

dforc

BOTTOM REINFORCEMEN

TTgs

kN/m2

gs kN/m3

TOP REINFORCEMEN

T

Actual(N/mm2) Allowable(N/mm2)

Coeffcient of friction, m=2/3TANfONE WAY SHEAR

AT 'D' FROM FACE OF

PEDESTAL

ONE WAY SHEAR AT '2D' FROM

FACE OF PEDESTAL

PUNCHING SHEAR FORCE

kN/m2

Characteristic strength of steel fy = 500

Clear Bottom cover = 50 mm

Clear Top cover = 50 mm

Enhanced shear strength for one way : USED 2

shear (Used / Not Used):- NOT USED

PROVIDE BOTTOM REINFORCEMENT(B):-

X-Direction T12 @ 200mm c/c spacing

Z-Direction T12 @ 200mm c/c spacing

PROVIDE TOP REINFORCEMENT(T):- Z (N-S)

X-Direction T12 @ 200mm c/c spacing

Z-Direction T12 @ 200mm c/c spacing

X (E-W)

kN/m2

Cb

Ct

Bz &Tz

Bz&Tz

Bx & Tx

DESIGN CALCULATIONS(As per EC-2-2004):-

DESIGN CALCULATIONS:-

1.0 Design Data:-

Thickness of footing D = 300 mm

Clear Bottom cover = 50 mm

Clear Top cover = 50 mm

Characteristic strength of con = 25

Characteristic strength of stee = 500

2.0 Design of Bottom Reinforcement:-

X-DIRECTION - Main Z-DIRECTION - Secondary

Assumed bar diameter = 12 mm = 12 mm

Effective depth provided = #VALUE! mm = ### mm

Maximum design Moment Mu = #REF! kNm = #REF! kNm

= #REF! #REF! = #REF! #REF!

#REF! #REF!

z = 0.5*d[1+sqrt(1-3.53 K)] ≤ 0.95 d = #VALUE! mm = ### mm

Tension Reinforcement Ast = #REF! = #REF!

% of reinforcement = #REF! % = #REF! %

Minimum % of steel = 0.135 % = 0.135 %

Minimum Tension Reinforceme = 404 = 404

= #REF! = #REF!

Ast per metre provided 12 tor @ 200 c/c spacing 12 tor @ 200 c/c spacing

= 565 = 565

= #VALUE! % = ### %

#REF! #REF!

Cb

Ct

fck N/mm2

fy N/mm2

f1 f2

dprov

K = Mu / bd2 fck

mm2 mm2

Ast,min mm2 mm2

Ast ,required ( max ( Ast , Ast,min) mm2 mm2

mm2 mm2

3.0 Design for Top Reinforcement:-

Downward pressure due to

Soil weight = 18.00

Foundation wt = 7.50

Grade slab = 0.00

Live load LL = 0.00

Dead load factor = 1.4

Live load factor = 1.6

Max Factored downward pressure

1.4(gs(dfgl-D)+gcD+gcTgs = 35.70

X-Direction Z-Direction

Max Projection proj = #REF! m = #REF! m

Ultimate Moment = #REF! = #REF!

= #REF! kNm/m = #REF! kNm/m

Effective depth provided 300-50-12-12/2

= 232 mm = 232 mm

= #REF! = #REF!

= #REF! = #REF!

z = 0.5*d[1+sqrt(1-3.53 K)] ≤ 0.95 d = #REF! mm = #REF! mm

Top Tension Reinforcem = #REF! = #REF!

% of reinforcement = #REF! % = #REF! %

Minimum % of steel = 0.135 % = 0.135 %

Minimum Top Tension Reinforcement reqd = 404 = 404

Area of steel required = #REF! = #REF!

Ast per metre provided 12 tor @ 200 c/c spacing 12 tor @ 200 c/c spacing

= 565 = 565

= 0.244 % = 0.244 %

#REF! #REF!

gs(dfgl-D) kN/m2

gcD kN/m2

gcTgs kN/m2

kN/m2

kN/m2

Mu

dprov

Mu/Fckbd2

Ast = ( Mu / 0.87 fy z ) mm2 mm2

ptmin

mm2 mm2

mm2 mm2

mm2 mm2

4.0 One way shear:-

X-Direction Z-Direction

4.1 Check for One Way Shear at d from face of pedestal:-

Max Shear Force at 'd' distance from face of Vu = #REF! kN/m = #REF! kN/m

Shear Stress per meter width v = #REF! = #REF!

= #REF! N/mm² = #REF! N/mm²

Design Concrete Shear Stress/m = ≥

= 0.12

k = #VALUE! ### k = ### #VALUE!

= #VALUE! % = ### %

= 0.00 No Axial Load Envisaged

= #VALUE! ≥ ### N/mm² = ### ≥ #VALUE!

= #VALUE! N/mm² = ### N/mm²

= #VALUE! N/mm² = ### N/mm²

Allowable Concrete Shear Strength = ### N/mm² = ### N/mm²

### ###

5.0 Check for Punching Shear:-

5.1 Design Shear Stress at the face of the Pedestal

Maximum Punching shear force = #REF! kN

Perimeter of the loaded area u =

= #VALUE! mm

=

Shear Stress = #REF! N/mm²

< #VALUE! N/mm²

< ###

vRd,c

CRd,c

≤ 2.0 ≤ 2.0

ρ1 ρ1

σcp

vRd,c

Enhanced Concrete shear strength,2dvc/av

(Where av = d)

Vat face

Column Perimeter + 4 x π x d

VEd Vat face/ (u x d)

VEd

VEd vRd,c

DESIGN CALCULATIONS(As per IS456-2000):-

DESIGN CALCULATIONS:-

1.0 Design Data:

Thickness of footing D = 900 mm

Clear Bottom cover = 75 mm

Clear Top cover = 75 mm

Characteristic strength of concrete = 30

Characteristic strength of steel = 500

2.0 Design of Bottom Reinforcement:-

X-DIRECTION

Assumed bar diameter = 16 mm

Effective depth provided = 809 mm

Mx 7

Maximum design moment Mu = 7.42 kNm

= 0.011

% of reinforcement req = 0.00 %

xu/d for balanced section = 0.46

% of reinforcement for balanced section = 1.13%

> 0.00 %

No Comp Reinf Req

Minimum % of steel = 0.12 %

= 0.12 %

Ast / m = 0.12 x 1000 x 900/100

Area of steel required = 1080

Ast per metre provided 16 tor @ 125 c/c spacing

= 1608

= 0.20%

3.0 Design for Top Reinforcement:-

Downward pressure due to

Soil weight = 18.00

" Foundation wt = 22.50

Grade slab = 0.00

Live load LL = 0.00

Dead load factor = 1.5

Live load factor = 1.5

Max Factored downward pressure

= 60.75

X-direction

Max Projection proj = #REF! m

Cb

Ct

fck N/mm2

fy N/mm2

f1

dprov

k=Mu / bd2

% of Ast ,required ( max ( pt , pt,min)

Ast

mm2

mm2

gs(dfgl-D) kN/m2

gcD kN/m2

gcTgs kN/m2

kN/m2

1.5(gs(dfgl-D)+gcD+gcTgs)+1.5LL kN/m2

pt≡1−√1− 4k

0 .87FckFy

50Fck

xu ,maxd=7001100+0 .87 fy

pt ,lim=41 .3(FckFy )( xud )

Ultimate Moment = #REF!

= #REF! kNm/m

Effective depth provided 900-75-12-12/2

= 807 mm

= #REF!

= #REF!

% of reinforcement req = #REF!

Minimum % of steel = #REF!

= #REF!

Ast / m = #REF!

Area of steel required = #REF!

Ast per metre provided 12 tor @ 200 c/c spacing

= 565

= 0.070%

#REF!

4.0 One Way Shear:-

X-direction4.1 Check for One Way Shear at d from face of pedestal

Maximum design shear at d from face of pedestal Vu = #REF! kN/m

Shear Stress t = #REF!

= #REF! N/mm²

= 17.519

Design Concrete Shear Strength = 0.33 N/mm²

= 0.67 N/mm²

(As per cl.40.5 of IS456)

Allowable Concrete Shear Strength = #REF! N/mm²

#REF!

4.2 Check for One Way Shear at 2d from face of Pedestal

Maximum design shear at 2d from face of pedestal Vu' = #REF! kN/m

Shear Stress = #REF!= #REF! N/mm²

Design concrete shear strength = 0.33 N/mm²

#REF!

5.0 Check for Punching Shear:-(Punching shear calculations as per BS8110-1997)5.1 Maximum Allowable Shear Stress

V max = = 4.38

5.00

whichever is less. Therefore = 4.38

5.2 Design Shear Stress at the face of the Pedestal

(As Per Cl 3.7.6.4 of BS 8110 : Part 1: 1997)

Maximum Punching shear force = #REF! kN

Perimeter of the loaded area, U = 1200 mm

Mu

dprov

k=Mu/bd2

ptmin

% of Ast ,required ( max ( pt , pt,min)

Ast

mm2

mm2

Enhanced Concrete shear strength,2dtc/av(Where av = d)

t'

tc'

(As Per Cl 3.7.7.2 of BS 8110 : Part 1:1997, max shear strength is max of 0.8(fcu)1/2 and 5N/mm2)

0.8 x (fcu)1/2 N/mm2

N/mm2

n max N/mm2

Vatface

pt≡1−√1− 4k

0 .87FckFy

50Fck

τc=(−1+√1+5 β )×0 .85×√0 .8 fck

6 β

β=0.8 fck6 .89 pt

Nominal Design Shear Stress, == #REF!= #REF!

Check : = #REF! <

#REF!

5.3 Design of Shear Stress at the Distance of 0.75 d from the face of Pedestal

(As Per Cl 3.7.7.4 of BS 8110 : Part 1: 1997)

Maximum Punching Shear force = #REF! kN

Perimeter of the loaded area, U = 6054 mm

Distance from the loaded area av = 607 mm

Allowable Shear Stress at 0.75d, = (1.5 d / av )

= 0.33 x 1.5 x 809 / 607

= 0.67

Nominal Design Shear Stress, == #REF!= #REF!

Check : = #REF!

#REF!

5.4 Design of Shear Stress at the Distance of 1.5 d from the face of Pedestal

(As Per Cl 3.7.7.4 of BS 8110 : Part 1: 1997)

Maximum Punching Shear force = #REF! kN

Perimeter of the loaded area, U = (2*(300+3*809)+2*(300+3*809))

10908 mm

Nominal Design Shear Stress, == #REF!= #REF!

Check : <vc = #REF!

#REF!

n Vat face/ (u x d)

n N/mm2

n < n max

V0.75d

n c ' n c .

N/mm2

n V0.75d /(U x d)

n N/mm2

n < n c' < n max

V1.5d

n V1.5d /(U x d)

n N/mm2

n

Z-DIRECTION

= 16 mm

= 809 mm

Mz = (Wl^2)/2

7 kNm

= 7 kNm

= 0.0113

= 0.00 %

= 1.13 %> 0.00 %

No Comp Reinf Req

= 0.12 %

= 0.12 %

= 0.12 x 1000 x 900/100

= 1080

16 tor @ 100 c/c spacing= 2011

SAFE = 0.25% SAFE

Z-direction

= #REF! m

f2

mm2

mm2

= #REF!

= #REF! kNm/m

= 807 mm

= #REF!

= #REF!

= #REF!

= #REF!

= #REF!

= #REF!

= #REF!

12 tor @ 200 c/c spacing= 565= 0.070%

#REF!

Z-direction

= #REF! kN/m= #REF!= #REF! N/mm²

= 14.016

= 0.37 N/mm²

= 0.74 N/mm²

= #REF! N/mm²

#REF!

= #REF! kN/m

= #REF!= #REF! N/mm²

= 0.37 N/mm²

#REF!

(OR)

mm2

mm2

4.38

(2*(300+3*809)+2*(300+3*809))

N/mm2

N/mm2

N/mm2

DESIGN OF FOUNDATION:1.0 Footing Data

Unit Weight of Concrete 25.00 kN/m3Grade of Concrete 30.00Net SBC 250Increament factor for BC 1.00Concrete cover 75.00 mm

0.95 mPedestal height above Ground level 0.50 mTenion load 7.00 kNUnit Weight of soil 18.00Angle of internal friction f 30 degreeCoeffcient of friction m 0.50FOS against Overturning 2.00FOS against sliding 1.5

X-Dirn Z-Dirn Y-DirnPedestal Size(mm) 350 450 50Footing Size(mm) 1000 1000 900Eccentricity,e(mm) 0 0 0

Load acting at(Top of Pedestal/Bottom of Footing):

Shear, Fx(kN)

D.L+W.L 0.1 2.746 0.2 0 3.248

Gross SBC = = = 267

2.0 Vertical load acting at bottom of foundation

Axial Load Py = 0.10 kNWeight of Pedestal Wp Lp x Bp x (Hp) x 25 = 0.20 kNArea of foundation ( Provided ) A L * B = 1.00Load due to soil Ws = 0.76 kNWeight of footing Wf A*D*25 = 22.50 kN

Total Vertical Load Pv Py+Wp+Ws+Wf+Wgs+Wll = 23.56 kN

3.0 Moment acting at bottom of foundation(about x-axis)

Moment Mx = 0 kNmMoment due to lateral force = 0.19 kNmMoment due to eccentricity (ez) (Py+Wp)*ez = 0.00 kNm

Moment acting at bottom of foundation Mxx = 0.19 kNm

Eccentricity along Z-Direction from cg of Footing, ez' Mxx/Pv = 0.008 m <B/6

4.0 Moment acting at bottom of foundation(about z-axis)

Moment Mz = 3.248 kNmMoment due to lateral force Fx = 2.6087 kNmMoment due to eccentricity (ex) (Py+Wp)*ex = 0.00 kNm

Moment acting at bottom of foundation Mzz = 5.86 kNm

Eccentricity along X-Direction from cg of Footing, ex' Mzz/Pv = 0.249 m >L/6

5.0 Bearing Pressure Calculation:-

Eccentricity along X-Direction from cg of Footing, ex' Mzz/Pv = 0.249 mEccentricity along Z-Direction from cg of Footing, ez' Mxx/Pv = 0.008 m

N/mm2

SBCnet kN/m2

fbc

Depth of foundation below ground level ,dfgl

gs kN/m3

Load case/Node

number

Axial Load, Py(kN)

Shear, Fz(kN)

Moment, Mx(kNm)

Moment, Mz(kNm)

fbc x SBCnet + gs x dfgl kN/m2

m2

gs*(dfgl - D)*(A - (Lp x Bp))

Mlfx Fz * dforc Mecc

Mx+Mlfx+Mecc

Mlfz Fx * dforc Mecc

Mz+Mlfz+Mecc

Teng Value k = 2.724

Maximum Bearing Pressure fmax kPv/A = 24.70Minimum Bearing Pressure fmin Pv/A(1-6ex'/L-6ez'/B) = 22.42

Bearing capacity Ratio BCR fmax/Gross SBC = 0.09Safe

6.0 Check for Stability:-X-Direction Z-Direction

Overturning Moment = 0.19 kNm = 5.86 kNmRestoring Moment = 11.78 kNm Pv x B/2 = 11.7776 kNmStability Ratio = 61.99 = 2.01

>2 Safe >2 Safe

7.0 Check for Sliding:-

X-Direction Z-Direction

Sliding Force = 2.746 kN = 0.2 kNResisting Force = 11.78 kN = 11.7776 kNSliding Ratio = 4.29 = 58.8878

>1.5 Safe >1.5 Safe

8.0 DESIGN FORCE CALCULATIONS:-8.1 X-Direction:-

Pressure variation :-

Maximum Pressure Pv/A(1+6ex'/L) = 24.70Minimum Pressure Pv/A(1-6ex'/L) = 22.42Design Moment:-Distance from left edge to face of pedestal = 0.325 mDistance from right edge to face of pedestal = 0.275 mMoment at west face of pedestal 24.7*0.325*1000*0.325 = 1.30 kNm/mMoment at east face of pedestal 24.7*0.275*1000*0.275 = 0.93 kNm/mDesign Moment Mxu = 1.30 kNm/m

One way Shear:-Effective Depth = 817.00

= 0.8170 mDistance from left edge to d distance from west face of pedestal = 0.000 mDistance from right edge to d distance from east face of pedestal = 0.000 mShear at d distance from west face of pedestal 24.7*0 = 0.00 kN/mShear at d distance from east face of pedestal 24.7*0 = 0.00 kN/mDesign Shear at d from face of pedesVxu Max Vx = 0.00 kN/m

Shear Stress at critical section = 0.00As per Clause 3.4.5.8 of BS 8110 Part= (0.79*0.2^(1/3)*max of((400/817,1)^0.25/1.25*(30/25)^(1/3))Alllowable Shear Strength of concrete 0.459

9 Z-Direction:-Pressure Variation:-Maximum Pressure Pv/A(1+6ez'/B) = 58.70Minimum Pressure Pv/A(1-6ez'/B) = -11.59

Design Moment:-Distance from top edge to face of pedestal = 0.325 mDistance from bottom edge to face of pedestal = 0.325 mMoment at north face of pedestal 58.7*0.325*0.325/2 = 3.10 kNm/mMoment at south face of pedestal 58.7*0.325*0.325/2 = 3.10 kNm/mDesign Moment Mzu = 3.10 kNm/m

kN/m2

kN/m2

Mo

Mr=Pv x L/2Mr/Mo

Hs

Hr = mPvHs/Hr

kN/m2

kN/m2

dx

N/mm2

N/mm2

kN/m2

kN/m2

10 Punching Shear Force:-At face of the pedestalCritical section of at a distance 2d from face of footingCritical perimeter = 2A + 2B

A = 1167.000B = 1267.000

= 4868.00 mm

Area with the perimeter = ###= 8.38E+06 mm^2

Punching shear force = 36.514 kNd = 817 mm

Shear Stress = 0.01

= 0.8 Roof of Fck

= 4.38

11 Design of Bottom Reinforcement:-Thickness of footing D = 900 mmClear Bottom cover = 75 mm

Clear Top cover = 75 mm

Characteristic strength of concrete = 30

Characteristic strength of steel = 500

Effective Thickness of Footing = 817.00 mm

Mx = Base Pressure * Width of Footing * Cantilever projectionMx = 1.104 kN.m

K = M / Fck*b*d^2= 0.000

K' = 0.156K < K'

(No need Compression Reinforcement)Z = d*(0.5+SQT (0.25-k/0.9)Z = 817 mm

0.95*d = 776.15 mmAs = 3.27 mm^2

Minimum Percentage of Steel = 0.13 %= 1062.1 mm^2

Provide Reinforcement = 14 mmNo of Rod Required = 10.5810477057Provide number of Reinforcement = 5.6Provide Area of Steel = 1134.09333333 mm^2

Provide 14.00 mm Dia @ 150.00 mm both ways12 Check Uplift:

Tension in Pedestal = 7.00 kNTotal Vertical load in Footing= 22.80 kN

Factor of safety = 3.256696429 > 1 Safe

VEd

vRd,c N/mm2

(As Per Cl 3.7.7.2 of BS 8110 : Part 1:1997, max shear strength is max of 0.8(fcu)1/2 and 5N/mm2) N/mm2

Cb

Ct

fck N/mm2

fy N/mm2