Minimum Standards for Structural Design | RCC Structures





Thumb rules for Structural Design | RCC Structures

Design of RCC Structural Components

In this article, we are going to discuss the minimum standards that are to be followed for the design of Structural components of a building such as Columns, beams, slab and foundation. We will also discuss the minimum safe standards for the reinforcing bars that are to be used for the design of the above mentioned Structural Components.

Minimum cross-sectional dimension for a Column: is 9”x9”. But to avoid slenderness ratio problems in multistorey buildings, we prefer a rectangular column design of 9″x12″ which is safer.

Also check out:

Thumb rules for making a Column Layout

Construction on Site | Design of RCC Structures

Construction on Site | Design of RCC Structures

Minimum RCC beam size:  is 9″x9″. But generally, to maintain uniformity and speed of construction, we design all beams of the same size 9″x12″. But 9″x9″ can also be used safely, according to design.

Minimum thickness of RCC slab is 4.5″ because a slab may contain electrical pipes embedded into them which could be 0.5″ or even fatter for internal wiring, which effectively reduces slab depths at certain places, causing cracking, weakening and water leakage during rains. So, a minimum thickness of 4.5″ should be maintained.

Minimum size of foundation for a single storey of G+1 building, where soil safe bearing capacity is 30 tonnes per square meter, and the oncoming load on the column does not exceed 30 tonnes, a size of 1m x 1m or 3′ x 3′ should be used. Even if the load is less (for example only 20 tonnes) then also the minimum is 3’x3′ and depth of footing should be atleast 4′ below ground level if not more…

Reinforcing bar details (minimum)

1. Columns: 4 bars of 12mm steel rods FE 415

2. Beams: 2 bars of 12 mm in the bottom and 2 bars of 10 mm on the top.

3. Slab

a) One Way Slab: Main Steel 8 mm bars @ 6″ C/C and Distribution Steel of 6 mm bars @ 6″ C/C

b) Two Way Slab: Main Steel 8 mm bars @ 6″ C/C and Distribution Steel of 8 mm bars @ 9″ C/C

4. Foundation: 6″ of PCC layer comes first. Over than, a tapered or rectangular footing of 12″ thickness is minimum. Steel mesh of 8 mm bars @ 6″ C/C should be laid. In a 3′ x 3′ footing, this would consist of 6 bars of 8 mm on both portions of the steel mesh.

Those looking for more information on the design of RCC Structures, check out


Guide to Building Design



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  1. #1 by africa web on October 19, 2011 - 2:17 pm

    thanks a lot for the info because it helps us save from dubious consulting fees and it really helps us understand the real objective of construction design which is economy and feasibility.more power

    • #2 by BenzuJK on October 27, 2011 - 4:50 am

      Hello,
      We are glad that our articles have been helpful to you but it is to be remembered that you always consult a local Civil Engineer for the safe construction of your building. Gaining general knowledge about structures will prevent you from getting cheated but do not initiate the construction on the basis of your theoretical knowledge. An expert from the field of Structural Engineering has to be necessarily involved in the designing and construction of the building.

  2. #3 by africa web on November 3, 2011 - 2:56 pm

    sure madam, too good advice not to be ignored. hoping to learn more. once again thanks’. always at your website………………

    • #4 by Ringwang on December 28, 2011 - 3:12 am

      Thank for your kind info. that is really useful for all the civil engineer profession. i am proud of u

  3. #5 by Darman Nayyer on February 9, 2012 - 11:49 am

    Dear Benzu,

    I am very much impress from your articles like one in the link below:

    http://www.civilprojectsonline.com/civil-projects/minimum-standards-for-structural-design-rcc-structures/

    which seems to be a local project. I do prefab construction on a moderate scale which is not very popular here and therefore also want to diversify into RCC works. Can you please help me in providing structural engineering consultancy for my projects on professional bases? I live in Karachi Pakistan.

    Please let me know as soon as possible if you can help me.

    Regards,
    Darman Nayyer

  4. #6 by lalit kumar Agarwal on April 3, 2012 - 2:59 am

    thank you for providing such a lovely site. your work is really trustworthy.

  5. #7 by Santhosh on April 9, 2012 - 10:44 pm

    Dear madam

    i have seen the apartment towers are constructed by column size 6″ x 18″
    which Standard to refer for this minimum column dimensions?

  6. #8 by gautam on May 11, 2012 - 4:05 am

    madam what should be the thickness of concrete in a foundation and the size of slab for G+2, as i read out that for G+1 a minimum size is 1mx1m and the thickness is about 15 inches is enough.

    • #9 by BenzuJK on May 15, 2012 - 9:44 am

      Hello Gautam,
      All these depend on structural calculations. The loading calculations are very important in this case. The structural design depends on the plan of the building to a large extent. The planning determines the loading conditions on the structure. After having calculated the loads, the quantity of concrete and steel is calculated.
      I suggest you consult a local Civil engineer before taking any step. However, I would like to share a good news with you. We are launching a new business website where people can get their structural design done at minimal rates without having to go through much trouble.

      Tc.

  7. #10 by dr tushar date on May 15, 2012 - 7:12 am

    hello madam,
    i am in the process of construction of my house. please guide me regarding the depth of footing to be taken once the hard strata is reached.
    yoursuggestion is extremely valuable.
    thanks
    dr tushar date

    • #11 by BenzuJK on May 15, 2012 - 9:36 am

      Hello,
      Structural design is different for structures located in different places. It has to be done accordingly.
      I suggest you consult a local civil engineer for the purpose of Structural design and not do it yourself. This will ensure the safety of your house and your family.
      These articles are mainly for educational and knowledge purpose.
      I hope my suggestion will be taken into consideration by you.

      tc.

  8. #12 by Basir Ahmad on August 7, 2012 - 11:45 pm

    Hello BenzuJK,
    I am writing you for my own house building and have some questions. I want to build 6 x 14 meters two-story RCC building with concrete Saltbox roof-slab of 4.5″ thickness and 15 columns for building joints. Building is residential with live load of about 750 lbs. please if possible tell me about the Minimum Standards for Structural Design of mentioned building because I am not able to pay for a local civil engineer and I will build mentioned building during 2-4 years to cover expenses for.

    Regards and Thanks,
    Basir
    From Afghanistan

    • #13 by BenzuJK on December 6, 2013 - 6:30 am

      There are no minimum standards that can be used. Total load on every column has to be calculated in order to design the column and its foundation.

      The load carrying capacity of a 9″x9″ column with 4 bars of 12 MM steel rods upto a height of 10′, with M15 concrete, is 30 Tons. That is the minimum, but in some practices, a minimum of 9″x12″ column is designed for slenderness ration factor. The design depends on a lot of factors, and is not black and white…

  9. #14 by vijay pratap on August 24, 2012 - 2:20 am

    Dear Benzu,
    I have been searching the net for some advice on structural design & it appears u can help me.
    I am trying to build a terrace garden on the roof of my 2nd floor flat in a area of 650 sq. ft.(total area of roof is 1500 sq. ft.). The columns are 10’x9”x15” (16mm-8 pcs & 8mm-4pcs steel), beams are 9″x16″ (16mm & 12mm steel) and the lintel is 125mm thick with 4″ & 5″ steel & is 4″ thick. All are RCC structures.
    I have got done the water proofing of the roof.
    My query is whether the roof can withstand load of 2″ of gravel + 2″ of stone crush sand + 8″ of soil and live load.
    I had consulted a few civil engineers who said yes it can but somehow they could not satisfy me with their reply.
    If u could guide me how to calculate the load bearing capacity of the structure and also please give tentative advice whether the structure can bear load (though i feel i am missing some information that u may require to calculate).
    Many thanks in advance.
    regards
    vijay

  10. #15 by sami on August 26, 2012 - 7:17 am

    i want to know how to take load calculation in beam when there is staircase,inclined beam also

  11. #16 by sami on August 26, 2012 - 7:19 am

    in hollow block slab ,when we provide hidden beam for that load calculation for slab purpose to be taken from center to center

  12. #17 by Abdul on September 25, 2012 - 6:16 am

    Hi Benz!!
    I really find this site educative..I am a new bee in this field..I am now planning to construct a 2-storey residential house with rooftop..is my 25cmX25cm column with 4-20mm rebars is safe? Average distance between column is 3.5m..waiting for your valuable comment..thanks a lot.
    Sincerely..
    Abdul

  13. #18 by P.Devender Mudiraj on September 27, 2012 - 11:56 pm

    Sir/Madam,

    Thank for your kind info. that is really useful for me.

  14. #19 by bevin on October 9, 2012 - 12:55 am

    Hi
    I am a civil engineer and I am currently planning on constructing a G + 2 bungalow of 3138sq ft ( 1130+ 1258+750). I have done a trial pit for the foundation depth. there is 2 ft of black cotton soil and there after the strata changes to a brownish soil mixed with stones
    I will be doing soil testing in a lab.
    Can you advice me what is the safe bearing capacity required for a RCC framed structure, having columns and footings with slabs
    Thank You
    Bevin

  15. #20 by george on December 1, 2012 - 3:27 am

    pls wat is G+1

    • #21 by BenzuJK on July 26, 2013 - 7:08 pm

      G+1 means ground floor + 1 (First floor)

  16. #22 by rephart on June 6, 2013 - 10:18 am

    pl give me details for constructing a large rcc undergound tank, 500 kilo litre, for our community to collect rain water.

  17. #23 by Fayyaz on November 6, 2013 - 10:42 am

    awesome effort……….like it

  18. #24 by John Mathew on March 3, 2014 - 2:54 pm

    Dear Sir/Madam
    I am planning a double storey in 2200sft (GF~1400 and FF~800). Architect has given the following foundation: 20cm PCC bed concrete/60cm Rubble masonry (upto Ground)/then 45cm rubble masonry and 12cm Plinth beam RCC upto Plinth. Load bearing clay brick walls for super structure. The lintel beam is also of 12cm depth. My doubt is whether we should go for 15cm plinth beam and lintel beam instead of 12cm beams? Is 12cm sufficient or 15cm thickness better.
    The soil is lateritic
    Sincerely
    John Mathew

    • #25 by BenzuJK on March 20, 2014 - 5:56 pm

      Hello John,

      I am not trained to design load bearing structures. So I wouldn’t know for sure. But bigger is always better, so you could use 15cm plinth and lintel beams instead of 12cm to be on the safe side.

  19. #26 by uday on August 6, 2014 - 7:03 pm

    i have one industrial purpose shed and have 9*16 pillar (4+4)
    height is 18 feet and thay keep just steel roof no concrete slab now i want slab of 6 inch on it and want further one floor on it size of shed is 17*40 feet
    please do guide me if you reply i ask further more i like to ask about changes i need to do

  20. #27 by P,K,Parameswaran on October 30, 2014 - 2:06 pm

    Thank you. Looking for some good aparment under construction, I located the multi-storeyed “Prestige Downtown” in progress in Vembuliamman koil street, West K.K. Nagar, Chennai. 78. The columns in superstructure have a uniform slender sectional dimention of 6”x24″ throughout. CMDA approved plans are not kept at site. Only, the builders plans for construction is available. i felt this is not in conformity with the Indian standards. i wish to be clarified on the following to enable me to proceed further:
    -Is it approved by CMDA?
    -has it been verified at site by CMDA?
    -are the set-back conditions as approved?
    -is check by CMDA on the dimentions and quality of construction happening as per norms?
    i shall be much obliged for a prompt reply.-

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