Contents
Slab:
Slabs are constructed to provide flat surfaces, usually horizontal, in building floors, roofs, bridges, and other types of structures. The slab may be supported by walls, by reinforced concrete beams usually cast monolithically with the slab, by structural steel beams, by columns, or by the ground.
Slabs are classified into two types:
- One Way Slab
- Two Way Slab
You can also read 16 Different types of Slabs in Construction
One Way Slab:
One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. The ratio of longer span (l) to shorter span (b) is equal or greater than 2, considered as One way slab because this slab will bend in one direction i.e in the direction along its shorter span
Due to the huge difference in lengths, the load is not transferred to the shorter beams. Main reinforcement is provided in shorter span and distribution reinforcement in a longer span.
Example: Generally all the Cantilever slabs are one Way slab. Chajjas and verandahs are a practical example of one way slab.
Two Way Slab:
Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along with both directions, it is known as two way slab. In two way slab, the ratio of longer span (l) to shorter span (b) is less than 2.
In two way slabs, the load will be carried in both the directions. So, the main reinforcement is provided in both directions for two way slabs.
Example: These types of slabs are used in constructing floors of a multi-storeyed building.
Difference between One Way Slab and Two way slab:
| One Way Slab | Two Way Slab |
|---|---|
| Slabs are supported by the beams on the two opposite sides | Slabs are supported by beams on all the four sides. |
| Main reinforcement is provided on shorter span due to bending | Main reinforcement is provided in both sides due to bending occurs on both sides |
| Main Reinforcement is provided in only direction for one way slabs | Main Reinforcement is provided along both the directions in two way slabs. |
| Loads are carried along one direction in one way slab. | Loads are carried along both the directions in two way slabs. |
One way Slab reinforcement details:-
From fig, it is clear that Ly/Lx = 8/3 =1 ≥ 2.66
Hence, One-way slab is adopted where Cranked bars (main bars) are provided on the shorter side of the slab due to bending. Distribution bars(straight bars) provided on the longer side as shown in fig.
Two way Slab reinforcement details:-
As per below fig, it is clear that Ly/Lx = 5/5 =1 < 2.
Hence, two way slab is adopted where cranked bars (main bars) are provided on both sides of the slab.
You can also read:-
10 Types of footings or foundations which we adopt in Construction
16 Different types of slabs in construction
Different types of Columns in construction
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Good Job Mr. Krishna this is very useful for all student & all civil engineers who doing a job …. Thank U Very Much for Creating a This Website..??
Thanks Mr.Naresh
It means a lot 🙂
Thanks for your work admin… There is a typing mistake for one way slab fig. example 8/3 = 1>= 2.66
Please check and correct.
oka animation video creat cheyandi sir,final year ki vachina kuda definations thapithe dani gurunchi deep ga ardam chesukoleaka pothunam
will do the same in future
me website lo manchi information vundi jobs use ayela,thankyou for providing this information.reading all articles yemaina doubts vunte meetho share chesukuntanu,thank you.
Sure 🙂 I am here to help u 🙂
my feedback is add photo option to comment so that doubts adagadaniki konchem easy ga vuntundi with photos help!
Hi Nani,
sure soon i ll update the same. Actuually if i give permission to add photo the server takes long time to open the webpage it decreases the speed of page so i didnt given permission will do the same after changing server. Stay tuned thanks for your valuble feedback.
Hats off sir
Very helpful for engineers.keep it up the efforts .My best wishes ……
THANKS FOR YOUR HELP SIR
Thank you Mr.krishna its very useful to all of us
Thnq sir,
This website is very helpful…
Thank you sir.
Good sir g
in some books there is a note: if ly/lx =1 the slab should be designed as one way slab. Is it correct?
no buddy it is wrong
Hello Krishna,
I will not only Thank you but will also pray for you to have more strength to continue with the assistance your rendering to the world of Engineering, once more thanks and more grece to your elbow.
Am from TN.. Ly/Lx =1 as two way slab in our theoretical studies but In site they are using oneway slab reinforcement design cause of due to economic cost wise low and Labour cost is low to compared with two way slab design… So, in site all are mostly provided one way slab.
Is it possible to indentify wheather the slab is one way or two way after construction of slab
It’s very useful information sir thank you
Good job sir.
Nice information sir
How much Cranked should be provided
Refer this article
Bar Bending Schedule of Slab
https://civilread.com/bar-bending-schedule-slab/
Supet guidance for civil engineers
Hi Sir
Please tell me about calculation of reinforcement used for two way slab of size 6.26mtr x 5.15mtr
Sir mai civil engineering diploma ka student hun or muje kon si book or teyari kese karni chahiye compitative exam nikalne ke liye plzz suggest sir
Your explanations with examples and diagram is very good, keep up the good work.
thankyou krishna for your guidence.
glad you loved it
What happens when we use two way slab as one way slab
I am civil engineering working in Ashoka buildcon Ltd what’s no 9102061947 add this group,