Tag Archives: Tor steel

This is BBS ..dear !

Friends ,

The Structure of a building is in Reinforced Cement Concrete.

The steel bars provided in the concrete make it strong to carry the tensile forces.

Thses bars are called as REINFORCEMENT.

The detailing of these bars [ Diameter ,spacing,covers, laps , dowel lengths, development lengths and shapes } are provided by RCC designer and are specified in the RCC drawing.

The extract of the steel reinforcement in the form of a table is known as Bar bending Schedule. The tabulation of the reinforcement details can be conviniently done using the MS Excel.

Professional contracting firms have got printed formats for BBS ready for the use of their staff. The BBS is prepared by the Qauntity Surveyors during estimation . The BBS is also prepared by the Site Engineers for controlling the quality of the Reinforcement Bars at site. The BBS is also an excellent tool for recording the measurements of the Reinforcement bars at site and the BBS can also be used to submit the Bills for the Reinf..bars.

This is a chart which basically gives the micro details about the various bars. This gives the dia, shape of bar , cutting length of the various bars in a RCC element such as Footing, column , beam ,slab etc.

The site engineer prepares the BBS based on the drawing and after due verification , hands it over to the reinforcement fitter.

By the use of BBS , the weight of the Re-bars can be easily calculated.

Let me explain you this popular tool with an example.

Imagine , there is a beam of the following cross section.


The details of the reinforcement have been tabulated in the following table :


The cutting lengths of each bar is calculated and tabulated as follows :


But you can see that many details are missing from this abstract. Hence , a better tabulation , known as the BBS has been prepared which gives each details of the Re-bar in a crystal clear method :


The bar bending gives a very clear picture of the reinforcement.


What is a TMT steel rod and what is the difference between HYSD and TMT bars? What are the pros of TMT bars over HYSD and mild steel?

Answer by Saket Roy:


I will keep it to the point as far as possible. For definition and detailed manufacturing process of TMT and HYSD bars you can of course Google or look at other answers. But how we Civil Engineers use these two terms matters the most, at least to me.
So, what do we call an HYSD :
HYSD = Torsed/twisted steel (TOR Steel Bars)
HYSD = Cold Twisted Deformed Steel Bars (CTD Steel Bars)
HYSD = High Yield Strength Deformed Bars (Of course!)

And, TMT Bars:
These are manufactured by a quenching and tempering process which allows the outer surface to cool much faster than inner core and hence making a temperature gradient from bar axis to periphery. This results in harder martensitic outer surface while the inner core cools slowly resulting in ductile inner core.

Now there is a catch! Technically TMT means a type of quenching and tempering process and it would not be precise to call it a Thermal+Mechanical treatment. Because, even the HYSD bars are treated at high temperatures and then rolled and twisted for shaping and hence it is also thermally + mechanically treated. So the difference lies in the exact process of making these two types of bars and not just in their names.

For pros of TMT bars over HYSD and mild steel you can refer to other answers and elsewhere but mainly TMT bars are superior than HYSD because of lesser residual stresses, more corrosion resistance due to hard surface and more ductility for similar strength grade.

What is a TMT steel rod and what is the difference between HYSD and TMT bars? What are the pros of TMT bars over HYSD and mild steel?