Guide to Design of RCC Columns





RCC Column

A column forms a very important component of a structure. Columns support beams which in turn support walls and slabs. It should be realized that the failure of a column results in the collapse of the structure. The design of a column should therefore receive importance.

Supporting the slabs is the main function of the columns… Such slabs are called Simply Supported Slabs. Simply supported slabs could be either one way slab or a two-way slab. It depends on the dimensions of the slab.

Reinforced Cement Concrete Column Plan and Section

Reinforced Cement Concrete Column Plan and Section

A column is defined as a compression member, the effective length of which exceeds three times the least lateral dimension. Compression members whose lengths do not exceed three times the least lateral dimension, may be made of plain concrete.

In this article, we are going to discuss in detail the basis of classification of columns and different types of reinforcement required for a certain type of column.

A column may be classified based on different criteria such as:

1. Based on shape

  • Rectangle
  • Square
  • Circular
  • Polygon

2. Based on slenderness ratio

  • Short column, ? ? 12
  • Long column, ? > 12

3. Based on type of loading

  • Axially loaded column
  • A column subjected to axial load and unaxial bending
  • A column subjected to axial load and biaxial bending

4. Based on pattern of lateral reinforcement

  • Tied columns
  • Spiral columns

Minimum eccentricity

Emin > l/500 + D/30 >20

Where,  l = unsupported length of column in ‘mm’

D = lateral dimensions of column

Types of Reinforcements for columns and their requirements

Longitudinal Reinforcement

  • Minimum area of cross-section of longitudinal bars must be atleast 0.8% of gross section area of the column.
  • Maximum area of cross-section of longitudinal bars must not exceed 6% of the gross cross-section area of the column.
  • The bars should not be less than 12mm in diameter.
  • Minimum number of longitudinal bars must be four in rectangular column and 6 in circular column.
  • Spacing of longitudinal bars measures along the periphery of a column should not exceed 300mm.

Transverse reinforcement

  • It maybe in the form of lateral ties or spirals.
  • The diameter of the lateral ties should not be less than 1/4th of the diameter of the largest longitudinal bar and in no case less than 6mm.

The pitch of lateral ties should not exceed

  • Least lateral dimension
  • 16 x diameter of longitudinal bars (small)
  • 300mm

Helical Reinforcement

The diameter of helical bars should not be less than 1/4th the diameter of largest longitudinal and not less than 6mm.

The pitch should not exceed (if helical reinforcement is allowed);

  • 75mm
  • 1/6th of the core diameter of the column

Pitch should not be less than,

  • 25mm
  • 3 x diameter of helical bar

Pitch should not exceed (if helical reinforcement is not allowed)

Least lateral dimension

  • 16 x diameter of longitudinal bar (smaller)
  • 300mm

Also check out:

Thumb rules for designing a Column Layout

Example of a Column Layout of a Residence

Consequences of Wrong Structural Design

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  1. #1 by Gulam on November 27, 2010 - 6:50 pm

    Very clear Information which I read & easy to understand and I think it will benificial to increase my knowledge, Thank you very much.

  2. #2 by Muhammad Qasim on December 21, 2010 - 12:01 am

    I like your details. But I not found any design problem with solution by equations. If you please mentioned some design problems then the topic “Design of Column” will be completed. Thanks.

  3. #3 by vernon on January 6, 2011 - 12:56 am

    this id simple and easy to understand.but the i coudnt found the topic of “how to design column” as said above.THank u.

  4. #4 by Pulak Mukherjee on January 9, 2011 - 11:54 pm

    an example of axially and biaxial loaded column may kindly be sent.

  5. #5 by Pulak Mukherjee on January 9, 2011 - 11:58 pm

    Design of various type of columns may kindly be provided under various condition of loading.

  6. #6 by bharat bhushan jindal on March 20, 2011 - 5:07 am

    Information given in very simple language… welldone…

    Also give the information in the lines of loading ..

  7. #7 by asddf on March 23, 2011 - 3:29 am

    Very good explaination of terms. Keep it up.

  8. #8 by chikku on March 26, 2011 - 3:11 am

    its deeply, easily, simply giving good information…?

  9. #9 by Desigual frakke on April 19, 2011 - 1:43 am

    I really admire engineer’s brilliant ideas. How they could come up with a solution which is in the context of applied science and mathematics.

  10. #10 by toseef on June 22, 2011 - 1:16 am

    thnx too this site
    onlyyyyy

  11. #11 by Abdul Raheem on August 27, 2011 - 11:15 pm

    Thanks for sharing your precious knowledge with us but appreciate more if u give us equational form of column design pattern with some illustrated problems.Hope my comment is clear.Thanks once more.

    • #12 by BenzuJK on August 28, 2011 - 8:21 am

      Thank you for the comment. Will definitely try and put up some numericals illustrating the RCC column design.

      Cheers:)

      • #13 by rahul on March 24, 2012 - 8:26 am

        is any book to clear the basics of structure..

  12. #14 by Mahesh Kumar Thapa on August 31, 2011 - 10:57 pm

    How does the shot column negativ affect can be reduced in RCC building.
    Mahesh Thapa
    Structural Engineer.

  13. #15 by Mahesh Kumar Thapa on August 31, 2011 - 11:00 pm

    Give me the idea about retrofiting of RCC column.

  14. #16 by brijesh shah on September 21, 2011 - 6:12 am

    nice…….. detail………..

  15. #17 by jabar on October 2, 2011 - 5:42 am

    this is very useful for my project column design

  16. #18 by jabar on October 2, 2011 - 5:58 am

    i like ur details.but i not fount any design problem with solution

  17. #19 by Ankur on October 13, 2011 - 5:49 am

    we have a our own land development company where we buy huge parcels of land and divide it make sub divisions and sell those small piece of land to individual developers builders.we are only involved with the plotted development of the land.Generally after buying land we take necessary permissions and do the paper work for the residential or commercial development.now we provide compound walls gate and R.C.C. cement roads to our clients.i checked your website for simple compound wall footing plinth column beam structure basic knowledge but i get lost as there is so much in it and its difficult to find simple things like this..could you help me with this?thanks in advance

    • #20 by NFOR W ROYEH on November 29, 2012 - 4:18 am

      After reading what you do i thought it will be nice to do business with you,there is a piece of land in Cameroon were we intend to construct a tall building for commercial purpose and will like if you can help give me advice on what to do. Thanks in advance.

  18. #21 by Mohiddin N O on December 8, 2011 - 12:32 pm

    i need an example on design of Long Column..

  19. #22 by Asim ALI on January 21, 2012 - 10:44 am

    wawo awesome……….it’s a simple and perfect answer that i was searching.
    thank you civilprojectsonline.com for helping me.

  20. #23 by christian on February 18, 2012 - 11:11 am

    …sir/ma’am how about the close spacing of lateral ties of column near the beam-column joints any rule of thumb or code specs.? cause what i have only knew is that frm code: not to exceed 48 tie dia.,16 bar dia. or least dim.
    cause as what i have always observed or seen in the actual there is always that close-spacing near the joints/supports. plz need reply, nd thank you & more powers.. .

  21. #24 by Narendiran on March 31, 2012 - 3:53 am

    Superb and simplified aricles many thanks

  22. #25 by Humayun on April 12, 2012 - 4:11 am

    Hello i read all design ,always upload design with the help of a example.

  23. #26 by MUHAMMED SHABEER C on July 20, 2012 - 9:46 am

    How wil determine ,effective length in x axis , y axis and unsupported length……..pls show with diagram

  24. #27 by abdul hameed khan on August 2, 2012 - 11:47 pm

    ….Can you please tell me,(a room 12′x14′,height 12′, in a normal house construction,ground floor and first floor,what should be the size of pillars?,can you please help me out,my house is under construction.

  25. #28 by santhosh on August 10, 2012 - 10:29 am

    very nice.also need area calculate and area marking information plz and TKS That mean THANKS

  26. #29 by d.ramachandran on October 17, 2012 - 7:41 pm

    wonderful knowledge u have …i am supposed to have put in more than 40 yrrs service …feel doubtful if i can do this .pl be writing …also suggest a good book for design of high rise building….we r not used to coputer design …how to do this c..more over in future only multy storeyed apts and offices will be in vogue…our mere concentration on small building is no good .of course the fundamentals r reqd… how the concreting is done for this with same labour who r nowadays used to max 6 or 7 storeys…crane is there..do they have the ladder system as u see in USA for plaster finish ..paint etc for high rause buildgs…hope u r the right person to answer my doubts ..if u do i will be grateful…u write excellent english …thanks…pl reply by mail….with best wishes…

  27. #30 by aziz on October 24, 2012 - 7:40 am

    hello,
    i would like to ask if a RC column designed as 500mm x 700mm x 7000mm (H). After striked formwork, we found that the size casted was 500mm x 690mm x 7000mm (H), are there has any problem to column strength. concrete cover is 40mm from main bar to concrete surface are achieved during inspection.

    TQ.

  28. #31 by s.sen on January 19, 2013 - 9:30 pm

    very very good explainatory guidelin for me, very much thanks to you.

  29. #32 by kiramat khan wazir on March 27, 2013 - 7:20 am

    ur details v.good for civil projects and for the student of civil engee. Always happyness for u and all human.

  30. #33 by Aftab on May 23, 2013 - 3:31 am

    Can we have a 6″x12″ columns for small houses in a plot area of 20′x40′
    Secondly, in such case what should be distance between columns and how deep should the beam be.

    • #34 by BenzuJK on July 26, 2013 - 5:06 pm

      Hello Aftab,

      Structural design is never done on assumptions. It requires professional knowledge which comes only after you have studied and practiced engineering for a while. I suggest that you should stop assuming the column sizes with regards to plot area. The size of the column depends on the plan of the structure. It also depends on the height of the building.

      You can seek professional advise with regards to structural design from the experts at Civil Projects online.
      Architectural and Structural Design Services by Civil Projects Online

      Cheers :)

  31. #35 by kumar on October 20, 2013 - 8:15 pm

    Impressive, Attentive & Thoughtful articles…..Thanks a lot Sirji

  32. #36 by Suman Singha on November 26, 2013 - 12:24 am

    Which of the following is the best procedure to filling up RCC column by concrete
    1. Filling up by steep by steep i,e half after half
    2. Filling the full column at a time.

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