## Guide to Foundation Design | Column Footings

#### Foundation Design

Foundation is the base of any structure. Without a solid foundation, the structure would not hold for long. We have to be very cautious with the design of foundations because our entire structure rests on the foundation. The job of a foundation is to transfer the loads of the building safely to the ground.

Laying of Column Footing Reinforcement | Foundation Design

The strength of the foundation determines the life of the structure. As we discussed in the earlier article, design of foundation depends on the type of soil, type of structure and its load. Higher the load bearing capacity of the soil, the larger the load it could safely carry.

Foundations are basically divided into Shallow Foundations and Deep Foundations.

In this article, we are going discuss the step by step guide to Column Footing Design for a shallow foundation.

#### Reinforced Concrete Footings

Footing comprises of the lower end of a column, pillar or wall which i enlarged with projecting courses so as to distribute load.

Footings shall be designed to sustain the applied loads, moments and forces and the induced reactions and to ensure that any settlement which may occur shall be as uniform as possible and the safe bearing capacity of soil is not exceeded.

In sloped or stepped footings, the effective cross-section in compression shall be limited by the area above the neutral plane, and the angle of slope or depth and location of steps should be such that the design requirements are satisfied at every section.

#### Design Procedure of Column Footings | Foundation Design

Here is a step-by-step guide to Column Footing Design:

Column Footing Plan and Section | Foundation Design

#### Step 1

Area required for footing

Square = B = (w+w1)/P0

Where,  Po = safe bearing capacity of soil

w1 = self weight of footing

w = self weight of footing

For Rectangle = b/d = B/D

A = b x d

Net upward pressure on the footing

q/p = W/A

#### Step 2

Bending Moment

Critical section for maximum bending moment is taken at the face of the column

For a square footing,

Mxx = q x B/8 (L – a)2

Mxx = q x L/8 (B – b)2

Myy = q x B/8 (L – a)2

#### Step 3

To fix the depth of the footing shall be greater of the following:

Depth from bending moment consideration

d =(M/Qb)

where, Q = moment of required factor

Depth from shear consideration

Check for one way shear

Check for two way shear or punching shear

Critical shear for one way shear is considered at a distance ‘d’ from face of the  column.

Shear force, V = qB [ ½(B – b) d]

Nominal shear stress, Tv = k . Tc

Tc = 0.16√fck

#### Step 4

Check for two way shear

Critical section for two way shear is considered at a distance at a distance d/2 from all the faces of the column.

SF, V = q [ B2 – (b + d)2]

SF, V = q [L x B – (a + d)(b + d)]

Nominal shear stress, Tv =  V/2((a+d)(b+d)d) ——- {for a rectangle

Tv = V/4((b+d)d)         ——- {for a square

Tv = k . Tc

k = 0.5 + β > 1                       ; [Beta β = ratio of sides of the column

Tc = 0.16√fck

Area of steel, Ast = M/((σ)stjd)

1. #1 by Nilesh Khorasiya on August 31, 2011 - 6:16 am

Sir,
As a general practice, we used to make Starter (of approx. 100mm ht.) for column formwork. But, from some expert, it is said that ht. of starter would be of 500mm ht. as per standard.
Could you pl. explain the exact mathods.
Thanks & Regards….

2. #2 by anuj on August 24, 2011 - 11:18 pm

how can i calculate column loads????
it would be very nice if you can give me some reference and your ideas

3. #3 by M.Thirumurugan. on August 13, 2011 - 11:45 pm

I strat next month my house work.house area is 1300 Sqft.kindly request to yoy please send footing and column sizes and reinforcement details and distance of every columns and roof slab thickness and reinforcement details. house size is 9m*12m

Thanks and Regards

M.Thirumurugan.

• #4 by BenzuJK on August 18, 2011 - 12:45 am

I would kindly suggest you to contact a certified Civil Engineer for the work.

Mr.Javed is an experienced Architect, civil engineer and an Interior designer.
Email: arjaved@gmail.com

4. #5 by naseer on August 6, 2011 - 5:07 pm

How can I design three storey building

5. #7 by fazil on July 26, 2011 - 3:45 am

Dear sir,
in a school building some of the footings are coming over a sloping rock.here the strata is hard but the slope may leads to slipping of footing .so wat will be the possible solution that i want to follow?

• #8 by BenzuJK on August 20, 2011 - 12:14 am

Hello Fazil,
The construction can be very well executed in a rocky terrain. You should keep one thing in mind while constructing on a rocky and slopy terrain; the rock which is being used for laying the foundation is not a loose rock, this could lead to structural failure. But if the rock is hard and solid but has a slope, then you need not worry about it. It would not affect the strength of the construction. I suggest, before you plan on initiating the construction, you should go for land surveying and get the important details which will help you figure out what kind of foundation is to be laid and if the construction is feasible in such a site. If you have any further questions regarding the construction, you are most welcome…. 🙂

6. #9 by S. S. Ahmed on July 25, 2011 - 12:36 am

Dear Sir,

I would request you to advise me about the foundation plan. what type and size of foundation required to carry out the 300Ton weight?

7. #10 by hari on July 12, 2011 - 7:41 am

which structure is more safe & cheap in two story building.
2. frame structure.

• #11 by BenzuJK on July 13, 2011 - 4:45 am

Hello Hari,
Preferably, you should go for Framed Structures and avoid Load bearing structures. Load bearing structure is safe for a two story building but framed structure would be the safest. Though there is a little difference between the construction costs but keeping in mind the long term usage, one must go for Framed Structures.
Also, the disadvantage of going for Load bearing walls for a two story building is that the walls get thicker and the inner space decreases. Since land has become so costly, going for a framed structure would be a sensible choice.

8. #12 by cabrin on July 8, 2011 - 12:42 am

9. #13 by kuttan on July 7, 2011 - 5:03 am

Hi Benz,
Thanks for the clarifications on earlier comments. I have my foundation ready now. Initially I planned for the red bricks for building the walls. Now changed it to cement blocks with MSand for plastering. What are the things I need to be careful while using the cement blocks with M Sand?

• #14 by BenzuJK on July 10, 2011 - 3:19 am

Hello Kuttan,
The only care you will have to take while constructing your walls with cement blocks is checking the alignment of the walls. A wall with cement blocks is more prone to collapse as compared to the red brick walls if the alignment is not proper.

10. #15 by MANOJ on July 6, 2011 - 9:53 pm

Hi,
i have to construct a house which has houses on both sides. what is the design for foundation and columns with out disturbing the sides of other houses. the critical situation is that i cannot afford space between the walls.

11. #16 by Softy on July 5, 2011 - 6:46 pm

If somebody don’t tie the column reinforcement to the mesh below then what will be the possible type of failures.What should be the design load to be taken for the footing design of a single storey, two storey, and 3 storey residential building ? I hope you can answer all my questions.

• #17 by BenzuJK on July 6, 2011 - 11:05 pm

Hello,
Tying the mesh to the column reinforcement keeps the foundation and column tied to each other which results in its stability and strength. Structural cracks might appear if one fails to do so.
As i have already explained earlier, four loads are to be considered in order to measure total load on the footing:
1) Self load of the column x Number of floors
2) Self load of beams x Number of floors
3) Load of walls coming onto the column

I hope I have made it clear.
Benzujk

12. #18 by tona.ahmed on June 29, 2011 - 10:11 pm

thanks for the post. I want to design the reinforcement for upward (negative) reaction. (As it happens in Factory shed where both positive and negative reactions should be check.)

need a technical help.

13. #19 by mohan kc on June 20, 2011 - 9:24 pm

hello, i wanna know the design procedure of doglegged staircase with rcc arrangement

14. #21 by khan on June 15, 2011 - 12:38 pm

what is the main difference between one way shear and two way or punching shear,when we have such shear in buildings?

thank u

• #22 by BenzuJK on June 16, 2011 - 11:56 pm

Hello Khan,
One way shear means stress coming onto the structural members in the horizontal direction from one side. It generally causes cracks in the RCC members. Two way shear is said to occur when the horizontal stresses occur from either sides of the members causing it to crack or result in crushing of the structural members if not designed properly.

Punching shear
It generally occurs between a column and a footing. The column tries to punch itself inside the footing because of the excessive stress on it. This could cause weak joints between columns and footings and also lead to structural failure.

15. #23 by Bassel on June 13, 2011 - 12:43 am

Dear Sir,
in case of having 3 pillars supported to on founation in triangle posetion, can please provide me the hence of the design in this case

Thanks
Bassel

16. #24 by khan on June 11, 2011 - 1:08 pm

what is the difference between one way shear and two way shear?

thank you

17. #25 by khan on June 11, 2011 - 1:06 pm

what is the difference between one way shear and two way shear?

is there two shear in any other RCC member apart from footing?

thank you

• #26 by BenzuJK on June 16, 2011 - 11:58 pm

One way and two way shear is found in beams and columns too but punching shear is only evident in between a column and a footing.

I hope it helped.

Benzu

18. #27 by srinivas on June 8, 2011 - 2:10 am

Sir, i constructed a single storey building, build up area is 900 sq.feet, the soil is hard and rocky, the depth of the footing is 6 feet, column footing size is 4’x4’feet, number of columns are 9, each column size is 12’x9′, rods used in column are four 16mm and two 12mm. plinth beam tie up with all eight columns one column is isolated, it is in parking area ( the rooms are 2 feet height compared to parking area ).
i would like to know plinth beam is really required for that isolated column and how many floors can i construct on this foundation. please give your valuable opinion.

thanking you,
srinivas.

• #28 by BenzuJK on June 17, 2011 - 12:09 am

Hello Srinivas,
Firstly, you need a plinth beam to tie the isolated column because if you dont do so, it might result into bending of column resulting in collapse.
4’x4′ footing size is pretty small. Your column steel design is good. If the column c/c are not more than 12′ than you could go for G+3 without any hesitation.

Benzujk

• #29 by Ringwang on December 22, 2011 - 2:14 am

• #30 by Abdul on September 27, 2012 - 11:20 pm

what does G+3 or G+2really means? i am confused..its actually new term for me..thanks

19. #31 by Imtiaz on May 20, 2011 - 11:11 am

Very good

20. #32 by Ashok R.Sharma on May 11, 2011 - 9:09 am

Hello,
How to calculate the total load will come on footing?

• #33 by BenzuJK on May 21, 2011 - 7:25 am

Four loads are to be considered in order to measure total load on the footing:
1) Self load of the column x Number of floors
2) Self load of beams x Number of floors
3) Load of walls coming onto the column

Benzujk

21. #34 by P.cHHETRI on May 3, 2011 - 10:37 pm

I am designing 3 storeyed building using staad pro, and sap software, I have probelem in defining load combinations. Can anyone one help me out..

22. #35 by tirumala on April 30, 2011 - 4:15 am

other than main and distribution reinforcement any other re bars will be there in footings

• #36 by BenzuJK on May 1, 2011 - 4:20 am

Hello Tirumala,
There are no other type of reinforcement bars in footings apart from main and distribution bars.

Cheers:)

23. #37 by vijay on April 22, 2011 - 9:17 pm

what will the column footing size genraly taken in 3storied resedential building

• #38 by BenzuJK on April 24, 2011 - 4:44 am

Hello Vijay,
The column footing size taken for a three storied building depends on the spans i.e. column to column distance. Generally the size of the column footing is taken as 4’6″x5′ for 4m c/c

24. #39 by Thomas on April 6, 2011 - 12:03 pm

I want to replace 3- 6×6 bearing posts in the basement of a 3 story wood structure. They are currently sitting on 2×8 wood on an existing 1-2 inch old concrete slab floor. I want to put new footings under posts. I’m using 6000 psi concrete mix, what size footing width x length x thickness should they be, and configuration of rebar?

25. #40 by Vicky on March 31, 2011 - 8:56 pm

what should be the design load to be taken for the footing design of a single storey, two storey, and 3 storey residential building ?

26. #41 by Sheeja on March 22, 2011 - 10:41 am

Sir,
I would like to know the follwing for the calculation bearing pressure below a footing, to know whether the pressure is below the safe bearing pressure of soil.
1. The unit weight of RCC below ground level to be taken is 25 KN/m2 or (25-15) KN/m2, where 25 is the unit weight of RCC and 15 is the unit weight of soil.
2. Whether weight of soil above footing, i.e, weight of backfilling to be taken.

• #42 by BenzuJK on March 29, 2011 - 2:09 pm

I didn’t understand your question. From what I could understand,

Weight of backfilling is negligible. I won’t affect the footing much… 15 kN/m2 is not much, when a typical building load per square meter can reach above 1000 kN/m2. Even for a simple 3-storeyed structure, loads on columns routinely cross 500 kN/m2

Cheers!

27. #43 by Labannya on March 9, 2011 - 11:16 pm

is 5″ brick wall safe for supporting a RCC slab? if not then why?

• #44 by BenzuJK on March 10, 2011 - 4:04 am

Hello Labannya,
Supporting a RCC slab on a 5″ brick is unsafe and not practical. It has to have a Column and beam structure above which RCC slab could be casted.
The reason is that there are heavy chances that the brick wall might slip which would lead to the collapse of the structure. I hope would find the answer helpful.

• #45 by bharat bhushan jindal on March 20, 2011 - 5:23 am

Hello….

what about the supporting of slab of shorter side span of 20 ft on brick columns.

• #46 by BenzuJK on March 29, 2011 - 2:10 pm

You can do that. A large brick column or a fat brick wall… But please consult with a local engineer for accurate calculations…

Cheers!

28. #47 by raghu on March 3, 2011 - 10:58 pm

can i have the eccentric footing design procedure

29. #48 by rajendravkurup on March 3, 2011 - 12:50 am

dear sir,
i want to design a pre engineering structure on top top of r c c framed design. size is 120m x 31m. please help me to find out how many columns and footing size to find out. load of pre engineering structure is 60 ton.

30. #49 by Kasi.Maheswara rao on February 10, 2011 - 1:35 am

Hi,
We have one old building without columns slab rest on brick wall. It’s constructed before 10 years, now walls are formed cracks the building is in oil and gas plant no of times wall chipping and reconstructed for windows and Ac opening pls suggest the building is suitable for living or need to dismantled

31. #50 by Ashish on February 10, 2011 - 12:30 am

what is the technical name of column between foundation footing and plinth beam .Is it stub column?

Ashish

• #51 by BenzuJK on May 21, 2011 - 7:49 am

Hello Ashish,
The column between foundation and plinth beam is called a stub column. It is squarish in shape. The dimensions of the column changes above the plinth beam…

32. #52 by rk khurana on February 7, 2011 - 9:17 pm

hi, I wish to know if in old structure foundation bolts and concret on surface damaged so to renew the foundation for steel structure. what can be done?

33. #53 by hari prasad on January 26, 2011 - 6:38 pm

I want to know waht is the load bering capacity of the rcc roof slab of 150mm thick simply supported

34. #54 by fanka kongnyuy on January 11, 2011 - 4:05 am

why do we determined the bearing capacity of the soil for foundation design

35. #55 by fanka kongnyuy on January 11, 2011 - 4:02 am

sir,
i wish to know why it is that when designing footings reinforced bars as placed closed to where the pillar will stand

36. #56 by Mano on January 3, 2011 - 5:41 am

can I give me an example for plinth beam design for a building foundation

37. #57 by Asit Baran Saha on January 3, 2011 - 3:05 am

Hi
pl. elaborate method of design of a combined footing connecting more than two cols. in line

38. #58 by Aseged on December 30, 2010 - 6:56 am

Hello
I am designing a G+1 Residential building that rests on a rock and the maximum column load I have got is 200KN. Since it is difficult to excavate the rock what is the possible solution and what minimum dimension of footing shall I use

39. #59 by Ram Sah on December 29, 2010 - 7:55 am

i need details load, vibration and wind force calculation tank foundation as folloing:

1.0 Foundation size = 8500 mm x 3200mm and need height
2.0 need re-bar datails fourmula
3.0 tank weight = 13 ton

i hope my request will receive kindly consideration by you..

Regards
Ram

40. #60 by Riji Sajan on December 28, 2010 - 1:01 am

please explain the the design three storey building column footing,plinth beam roof slab etc.

41. #61 by Pritam Roy on December 23, 2010 - 8:25 am

Dear sir
I want to build up a home of two storied building , area 22?x52?. so I need the rod calculation formula and also roofing, foundation,beam, column diagram.

• #62 by rajendravkurup on March 3, 2011 - 12:35 am

Pritam Roy :

Dear sir
I want to build up a home of two storied building , area 22?x52?. so I need the rod calculation formula and also roofing, foundation,beam, column diagram.

• #63 by BenzuJK on March 29, 2011 - 2:27 pm

Wouldn’t it be a better idea to contact a professional? It would be safer and cheaper to build according to a perfect design of an experienced professional.
I know an experienced Civil Engineer who is also an Architect, Javed Kachchhi.
http://www.architectjaved.com

42. #64 by Suman Dutta on December 22, 2010 - 6:14 am

Dear sir
I want to build up a home of two storied building , area 30’x25′. so I need the rod calculation formula and also roofing diagram.

43. #65 by SANJAY KUMAR on December 19, 2010 - 7:08 pm

dear sir,,
i want to build up a flat RCC roof for roofing area of 43′.4″x31’3″. so i need the rod calculation formula and also the roofing diagram.

44. #66 by vinod on November 18, 2010 - 12:57 am

why we do grouting at the column base plate??

• #67 by BenzuJK on May 21, 2011 - 10:22 am

Grouting at the column base plate helps in strengthening and stiffening of the column base. This could help in avoiding flexural and structural failure.

45. #68 by Mani on November 1, 2010 - 3:58 am

is Achorage requried for a 6feet x 6feet x 1.3feet footing. also kindly advise whether anchorage required for columns, plinth beams, and tie beams. kindly advise.

46. #69 by rajendra on September 18, 2010 - 11:47 pm

what will happen in footing if we provide larger dia long side and placed down and small dia to short side and placed above ?

47. #70 by deepa on August 3, 2010 - 3:13 am

Its good to find the whole design part in this if we hve images of various kinds of footing it wl be useful.

48. #71 by sateesh on July 20, 2010 - 11:31 pm

Hi,

Please explain me the design proedure of Generator building. what are the loads i have to consider.

Thanks,
Sateesh

• #72 by BenzuJK on July 28, 2010 - 2:06 am

Generator Building is a place where heavy machinery is placed. Firstly, you will have to study the kind of machinery that will be used in the Generator Building. Only then can you estimate the load on the building. Once you know the average weight of the machines and the number of machines that your design supports you can then move on with the load calculations. More than the live load of the workers or technicians, consideration of the dead load of the machinery plays a vital in the design of Generator Building.

• #73 by ikoto on May 12, 2011 - 5:49 am

can footing depth vary in same builing

49. #74 by amitava kar on July 10, 2010 - 8:25 am

I need to design a storey building how the load calculations r carried out that is coming in the column can pls tell

50. #77 by Mr.atiq on June 17, 2010 - 12:41 am

salam & hi,
can u explain me … that the proceture to calculate total load of single story building + how to determine the area for (width of foundation , depth of foundation , thickness of block & number of off sets)…
atiq….

• #78 by BenzuJK on June 17, 2010 - 3:05 am

Hi Atiq,

Foundation design is a complex process. It depends on the total load on a particular foundation as well as the Safe Bearing Capacity of the soil.

For example, a single storey building foundation with hard soil, where total load on footing does not exceed 300kN, a footing pit of 1M X 1M at a suitable depth upto hard strata would be sufficient. The pit would have a 6″ layer of PCC. On top of that, you would place a mesh of steel consisting of 8 rods each of 10mm diameter on both sides. Then place the column steel frame on top of it and tie the column bars to the steel mesh. Pour 6″ of concrete and let it harden. Then you can go for either tapered footing or block footing. Total thickness of block should be 15″, including the 6″ you of RCC poured earlier. So, for a single storey building whose load does not exceed 300 kN, and the soil strata is hard, the above given design should be sufficient.

• #79 by Asit Baran Saha on January 3, 2011 - 3:13 am

The concrete should be poured in one go.

• #80 by bharat bhushan jindal on March 20, 2011 - 5:20 am

If somebody don’t tie the column reinforcement to the mesh below then what will be the possible type of failures.

• #81 by BenzuJK on March 29, 2011 - 2:13 pm

Never observed any such failures in structures. So, am unaware of that. Maybe Google Search might help…

Practically speaking, column reinforcement is embedded in many feet of concrete. Ensuing footing would be weak, but I doubt if it would fail.

Cheers!

• #82 by Amba on March 15, 2012 - 1:48 am

Yes! you are correct! If at all the workman ship does not satisfy , like the plumb of the column/building), there are no failures observed.

• #83 by Ajaynder on August 26, 2011 - 1:09 am

There is no failure but the eccentricity of the column reinforcement might be disturbed, thats why its important to tie the reinforcement after alligning to the center line.

• #84 by BenzuJK on August 27, 2011 - 3:58 am

Hello Ajaynder,
When the eccentricity of the column reinforcement gets disturbed, it leads to structural cracks which results into structural failure. Structural failure does not just mean that “the structure would collapse” but it also means that the structural components like beams or columns in a structure are damaged which affects their strength considerably.

Cheers:)
BenzuJK

• #85 by Yash on December 5, 2011 - 1:26 am

If u do not tie your column to the bottom mesh… then there will be joint failure (probably cracks in diagonal direction will arise that is shear failure) between column and the other member.

• #86 by meenakshi on September 20, 2012 - 2:32 am

bharat bhushan jindal :
if we didn’t tie the longitudinal reinforcements of the column,then the bars may buckle and column will tilt..i hope u got ur ans

• #87 by kuttan on June 17, 2011 - 3:21 am

Hi Benz,
I am bit tensed aftre readiing this article. My 2 story building (1300+1200 sqft) foundation design consists a mesh of with 8mm rods and column steel frame of 12mm. Is this is sifficient for this building? there are around 17 columns in the foundation with beams connecting all the columns. Reammy appreciated your reply on this ASAP.

Sasi

• #88 by BenzuJK on June 17, 2011 - 3:36 am

Hello Sasi,
8mm rods can be used for the footing mesh. The number of steel rods change with the thickness of the mesh. So the mesh being 8mm or 10mm is not an issue. It all depends on the load coming on a particular footing. The load on every column is different depending on which we calculate the total quantity of steel required. If your engineer is qualified enough then don’t worry, he will take care of it. Your building will be safe.

• #89 by kuttan on June 20, 2011 - 4:00 am

Hello Benz,
Thanks for the quick reply. Just one more quiry. The beam size connecting all the columns are 30cmx20cm with avg span of around 4mts. Is it sufficeint dimension? just wanted to have second opinion. Also whether we need to extend the column pillars to to the roof level? My architect says its not required. Instead we can have 15 cm concrete belt with some additional rods running through out the plinth. Please advice.

• #90 by BenzuJK on June 25, 2011 - 10:31 pm

Hello,
This shall be fine. You can proceed with the construction. I don’t think there would be any problem.
All the best!

• #91 by kuttan on July 6, 2011 - 5:15 am

Hi Benz,

• #92 by BenzuJK on July 6, 2011 - 11:00 pm

Hello Mr. Kuttan,
You can always keep in touch with me through my site. You can ask any questions that have regarding the construction field. Will try me best to help you whenever possible.

Benzu

• #93 by Romal on January 5, 2015 - 10:47 am

Dear Sir,
I have 4 story building the foundation slab for each column is 1m2 and deepness is 70cm2 and beams connected in foundation each column 40x40cm with 6 each of 14mm rebar . it has totally 15 columns the size of the columns are 30x40cm each column has used 8 each of 16mm rebar and the soil of the fundation is strong. now please advice can i build one other story at the top of it to became 5 story. THANKS

• #94 by Edem on August 19, 2016 - 3:05 am

Please with the question asked by #17 person Romal, I need the answer seriously for a decision making.

• #95 by peris on July 6, 2012 - 1:05 am

hi,

am having problems in calculating foundation loadings.Are in a position to help?

Regards,
Peris

• #97 by satish on October 18, 2016 - 3:18 pm

yehh…If u consider G+3 bldg. go from top to bottom. first of all distribute the load of slab to the beam as per nature of slab i.e. if one way half-half or two way in trapezoidal & triangular section then beam will be loaded as VDL transfer this load to the supporting column .
same procedure done for 2nd & 1st & Ground floor but while go to down word direction add upper respective floor load then you’ll get the total load on column