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:

A2A.

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?

What is the difference between scaffolding, shuttering and framework as per civil engineering?

https://www.surveymonkey.co.uk/r/DTB5WZQ

Answer by Santosh Kulkarni:

Thank you so much for the A2A.
Ravishankar has already given a comprehensive answer to this question.
However , let us deal the same question from a different perspective.

1. Form work :
All arrangement done to support the green concrete till it attains the strength is known as form work or temporary work.
Form work determines the geometry,shape.size and finish of the form work.

2.Centering :
Part of the form work which supports the horizontal surface is called centering for example slab bottom  , beam bottom etc.

3.Shuttering :Part of the form work which supports the Vertical surface is called Shuttering for example column sides, beam sides,slab side ,wall side etc.

4.Staging : That portion which support centering & shuttering is called Staging. This can be :

1. Wooden Ballies
2. Pipes/Props/Jacks
3. H frames
4. Space frames using Coupler / Cup-Lock system

5.Scaffolding : That arrangement which is meant to be a supporting platform for people ( labor , supervisor, mason ,fitter,painter,carpenter etc. ) is known as scaffolding.

Now having defined the basic terms , let us see the site photographs for better understanding :

In case you are interested in finding out more about Form work  or have some questions about the rate analysis , do contact me with this form here :

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What is the difference between scaffolding, shuttering and framework as per civil engineering?

What is the difference between scaffolding, shuttering and framework as per civil engineering?

Answer by Ravi Shankar:

Scaffolding :
Scaffolding is nothing but a fixed/movable platform which can be used for working at heights . They are usually used for activities such as plastering, painting, brick work at heights etc.
There are various types of scaffolding :
1. Tube and Coupler Scaffolding: Assembled using tubes and couplers at joints.

2. Bamboo/Wooden Scaffold : It is made using bamboo materials. It is considered unfit for industrial use.

3. Suspended Scaffold : It is used for cleaning glass at malls usually.

Shuttering/Formwork :
Formwork is the term given to either temporary or permanent molds into which concrete or similar materials are poured. In the context of concrete construction, the falsework supports the shuttering moulds

So, By their defnitioons, scaffolds are for supporting man and materials and act as working platforms. Formwork(Shuttering) acts as moulds for pouring concrets.

What is the difference between scaffolding, shuttering and framework as per civil engineering?

How buildings are build?

Answer by Santosh Kulkarni:

Friend ,
The simplicity of your question is quite appreciable.
However, giving answer here seems to be a challenge.
May I suggest you one thing ,
Just visit this blog :
Construction basics re-told.
You shall find nearly 150 articles all written exactly from the same point of view as asked by you.

Each article has got ample photographs to illustrate the issue discussed.
If you desire , you can also follow this blog.
Once you have gone through this blog , do write specific questions which shall certainly be interesting to answer.
Hope you are able find what you seek.
All the best !

How buildings are build?

What is the initial setting time for cement or concrete?

What is the initial setting time for cement or concrete?

If you have a double glassed window and a polyurethane rolling shutter on the outside, what distance between them provides the best sound…

Answer by Micheal Chang:

The air space between the two won't actually matter much at all.

The transmission loss will be primarily provided by the double pane window assuming proper installation and weather sealing. The rolling shutters will contribute to the total attenuate at higher frequencies, but virtually nothing at lower frequencies due to its low mass and absence of tight seals.

Given the min/max distance constraints on such a window installation, I would just go with whatever is the most convenient from an installation and aesthetic viewpoint.

If you have a double glassed window and a polyurethane rolling shutter on the outside, what distance between them provides the best sound…

Are concrete or steel structures more vulnerable to earthquake?

Answer by Matthew Sutton:

Concrete is more problematic than steel due to its brittle nature. If the reinforcing is done correctly, particularly at the connections, (all beam/slab design per ACI should be OK), and around the shear walls they should be safe. I say ‘should’ because the current ACI and CBC code provisions are untested. The most recent seismic design provisions in CA were developed largely in response to Northridge. Ongoing research into structural failures in Japan and New Zealand will certainly yield new insights and new code recommendations, some of which may eventually get adopted…but these countries aren’t using the ACI code so it’s a bit of an apples to oranges comparison.

Steel structures are generally less susceptible to structural failure due to the ductile nature of steel and they’re ability to dissipate energy. However weak links like poorly designed braced/moment frames, connections, or soft story behavior with slender columns, can all compromise a steel building. Even steel buildings that survive an earthquake may be well beyond repair due to excessive damage or deflections.

Vulnerability needs to be defined with some precision–vulnerable to damage, less resilient, more of a threat to the life-safety of the occupants?

Are concrete or steel structures more vulnerable to earthquake?

What kind of concrete mix and dia of steel bars are used in high rise structures?

Answer by Arafat Basheer:

Differs from level to level and type of member. I worked in a project of G+27 and we used concrete mixes ranging from M50 to M30 in columns and beams, and  M35 to M25 in slabs higher mixes in lower levels and lower mixes in upper levels. Column reinforcements ranged from 32mm to 12mm depending again on location and level of structure. Shear walls had dense and higher dia bars, so did outer skeltal columns. Inner skeltal columns had lower dia as compared to outer columns.

What kind of concrete mix and dia of steel bars are used in high rise structures?

Why is ready-mix concrete so much more corrosive than hand-cast concrete?

Answer by Sumanth Reddy:

Cement is inherently alkaline and this results in an alkaline pore solution in concrete. It is quite alkaline if you think about it. It could reach as high a pH as 13.5 – 13.7.

The reason for this particular difference in ready mixed and hand mixed concrete could be due to the quantity of cement in the mix. I do not think any of the admixtures would have a significant effect on the alkalinity of concrete.

The temperature due to mixing will not play a dominant role since the rate of mixing is not high enough to generate additional heat and as for the heat of hydration, it relates to the quantity of cement again.

It would be interesting to know things like exposure time, temperature during operation, concrete strength and purpose of concrete (application) to consider other factors that could have influenced the observation.

Why is ready-mix concrete so much more corrosive than hand-cast concrete?

Why the size of standard cement concrete cube is fixed as 150 mm?

Why the size of standard cement concrete cube is fixed as 150 mm?