## Guide to Design of Simply Supported Slabs | Design of RCC Structures

#### What are Simply Supported Slabs?

Before we discuss the technical design rules of Simply Supported slabs, lets just go through its definition and learn why they are named so…

As the name suggests, simply supported slabs are supported on columns or stanchions…

Simply Supported Slab

Simply supported slabs don’t give adequate provision to resist torsion at corner to prevent corner from lifting.

The maximum bending moment will be given if the slabs are restrained. But atleast 50% of the tension reinforcement provided at the mid span should extend to the support. The remaining 50% should extend to within 0.1Lx or Ly at the support as appropriate.

RCC Slab Design depends on the on the dimensions of the slab after which the slab is termed as a one-way slab or a two-way slab…

In the design of RCC structures, Column Design and Beam Design are to be done before we start with RCC Slab Design…

#### Thickness of slab

l/d ratio should be less than the following:

• Simply supported slab
• Continuous slab, l/d = 26
• Cantilever slab, l/d = 7

In any case of the above, the thickness should not be less than 100mm

#### Effective span

• Distance between centre to centre of support
• Clear span plus effective depth

#### Minimum main reinforcement

• 0.15% gross c/s of slab – for MS bars
• 0.12% gross c/s of slab – for HYSD bars

#### Spacing of main bars

The spacing or c/c distance of main bars shall not exceed following:

• Calculated value
• 3d
• 300mm

#### Distribution or Temperature reinforcement

This reinforcement runs perpendicular to the main reinforcement in order to distribute the load and to resist the temperature and shrinkage stresses.

It should be atleast equal to;

• 0.15% gross c/s of slab – for MS bars
• 0.12% gross c/s of slab – for HYSD bars

#### Spacing of distribution bars

The spacing or c/c distance of distribution bars shall not exceed the following

• Calculated area
• 5d
• 450mm

#### Diameter of bars

The diameter of the bars varies from 8mm to 14mm and should not exceed 1/8th of the overall depth of the slab.

For distribution steel, the diameter varies from 6mm to 8mm.

#### Cover

The bottom cover for reinforcement shall not be less than 15mm or less than the diameter of such bar.

1. #1 by venkadeshwaran on September 7, 2010 - 8:12 am

ITS VERY USEFUL FOR ME AND IT MAKE EASY TO DESIGN SLABS, SINCE THE STEPS ARE PRECISE AND AS PER CODE. THANKS……..

2. #2 by yogesh joshi on January 3, 2011 - 3:00 am

good

3. #3 by kishan on January 18, 2011 - 9:00 am

i shall be thankful to provide guide lines.

4. #4 by kishan on January 18, 2011 - 9:03 am

I needed the knowledge of rcc design.

5. #5 by kishan on January 18, 2011 - 9:07 am

RCC Design required for project in PHED.

• #6 by BenzuJK on February 3, 2011 - 10:23 am

I would be really glad if I could be of some help to you. Send me your details regarding your PHD Project… We shall discuss the project in detail and do the best we can.

6. #7 by ANIRUDH SHIRKE on January 31, 2011 - 12:20 am

7. #8 by bral on February 28, 2011 - 3:32 pm

thanks for guideline.

8. #9 by VAMSI KRISHNA on March 23, 2011 - 1:20 pm

I am very much thankful for these guidelines.

9. #10 by VAMSI KRISHNA on March 23, 2011 - 1:21 pm

Very nice guidelines.

10. #11 by Asante John Amoah on March 28, 2011 - 10:23 am

i need a help about a surveyors role in dumping site of refuse

• #12 by BenzuJK on March 29, 2011 - 1:52 pm

I can guess a surveyor can be used in finding and utilizing optimum locations for dumping refuse in a such a way that the space can be reused for dumping in a few months after all the refuse has decomposed, and also ensure water table and surrounding environment remains safe from pollution.

But I don’t know very much about the subject.

Cheers!

11. #13 by Rob on May 10, 2011 - 7:10 am

Thanks for the detailed information — much appreciated!

12. #14 by Valerie on May 11, 2011 - 3:41 am

I’ve just discovered this site — so many interesting posts! I’m off to explore some more…

13. #15 by Ravi on August 17, 2011 - 3:57 am

can i cast rcc slab on 9″ thk brick wall for room size 12′ x 12′

14. #16 by dhrudat on August 27, 2011 - 11:58 pm

hi.i m m.tech student of structure engineering if anybody knows about fiber reinforced concrete then please reply me.

15. #17 by sree on August 31, 2011 - 12:51 am

I am very much thankful for these guidelines.

16. #18 by sree on August 31, 2011 - 12:51 am

I am very much thankful to you for these guidelines.

17. #19 by omojola benjamin ademola on October 12, 2011 - 12:10 pm

this is the most complete page for design i therefore recomend it engineer and builder in the house to it for their design

18. #20 by Dilip W Jadhao on October 25, 2011 - 8:59 pm

The guideline that you are given which help me lot while designing of slab and other structure.So thanks for such nice guideline

19. #21 by PRASHANT on January 15, 2012 - 10:15 pm

thankful for these guidelines.

20. #22 by sareenparmod on May 14, 2012 - 11:57 pm

Informative for students and learners. Thanks and goodluck.

21. #23 by Fahee Haque on February 6, 2013 - 8:08 pm

Please send me guide lines regularly for support. Thanks

22. #24 by Shariful Islam on February 10, 2013 - 7:35 pm

It will be very helpful for civil Engineer, Thanks