Towards the cosmetics !

Good afternoon Readers ,

We are now at 11,025 views , 180 + days ,158 followers .

We are now entering the Phase 02 .

You shall wonder what is this all about ?

Right ?

During the first phase , we focused mainly on the building structures.

We dealt into Foundations, columns, beams, slabs,lintels, chajjas etc.

We talked about plain cement concrete , Reinforced cement concrete etc.

We described Form work and also explained Reinforcement steel.

We also talked about the masonry , brick work , AAC blocks etc.

Now we shall be dealing with the Finishing part of the buildings.

The topics would look something like this :

Flooring , Tiling , Plastering , Painting ,Waterproofing ,Plumbing , Sanitary etc.

So I thank you for giving total support for this blog.

Welcome to the Phase 02.

Can anyone tell me how steel quantity is calculated in the construction of a building, like footings, beams, columns, and slabs? How woul…

Answer by Santosh Kulkarni:

Great question .
May be I can throw some light on this.
There are 3 methods .
Each method has its own advantages and disadvantages.
Let us see them in brief.

 

Background :

RCC comprises of concrete and steel bars.

Concrete is strong in compression but weak in tension .

Therefore , steel bars when provided in RCC , give resistance against the tensile stresses.

The RCC drawings give each detail of the Reinforcement .

However, finding out the exact  weight of the steel bars is a job of the construction engineer. In big organizations , this job is entrusted to the Quantity Surveyor.

In smaller construction companies, this is done by the Site engineer.

Why weight of Steel bars is needed ?

1. For finding out how much quantity of steel bars we need to buy for the work.
2. For keeping an account of how much steel bars have been actually consumed in the RCC work.
3. For giving a reconciliation to the client regarding the steel bars issued and consumed.
4. For making a bill of the steel bars

 

 

Method 01 :
Thumb rule method :
I know from my past experience that a normal residential building needs around 3 to 4 Kg of steel per sqft .of built up. This data has been worked out from the previous projects . I also recommend to each student to keep this statistics updated for their projects.
Suppose you ask me how much steel shall be required for a residential project where built up area is say 22,000 Sqft.
My immediate answer would be 22,000 x 4 = 88,000 Kg or 44 MT.
Such method is useful for arriving at the purchase quantity or for taking quotations from the steel traders. There could be variations depending upon the design philosophy.

Method 02 :
From Bill of quantities .
Quantities of various RCC elements are known from the bill of quantities.
Now suppose we know that footings need 50 Kg/CuM of reinf. steel so an if the quantity of footings is 100 CuM , we come to know that reinf in footings shall be 50*100 = 5000 Kg or 5 MT.

Method 03 :
This is the most accurate method .
We take the RCC drawing and for each element , calculate the cutting length and nos for each of the bars.
Schedule of bar weight is also available.
Thus , we can find out :
W = N*CL*U
W : reinforcement weight.
N : Numbers
CL : cutting length
U : Unit weight of the bar

It is advisable to prepare a bar bending schedule which is very scientific method and is also useful for cross checking at site.

The bar bending schedule can be prepared manually or it can be prepared using the MS Excel sheets. If MS Excel sheets are used, it may take a slightly longer time initially but then in case of repetitive works , the task becomes easier to do.

Learn M.S.Excel 

In case you would like to see an example of Steel Bars calculations using the M.S. Excel Sheet , do contact me with this form :

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Hope there is enough clarity now !

Blog stats for future reference :

Can anyone tell me how steel quantity is calculated in the construction of a building, like footings, beams, columns, and slabs? How woul…

Why does concrete get harder as it ages?

Answer by Tim Simpson:

To be fair to Roman concrete, Luis Palas, the buildings in your picture of the Forum in Rome were not made of concrete, but marble. The building method was basically the stacking of one marble block on another, with simple cleats and pins holding things together. With time, perhaps earthquakes, theft for re-use and so on, such buildings suffer the fate shown.

Roman concrete, on the other hand, is a remarkable substance. It has a different composition than today’s Portland cement (concrete being the mixture of cement and aggregate, usually crushed rock of some sort). Roman cement was made differently than our cement, and lasts longer than modern concrete. Roman concrete is especially resistant to seawater.

As to modern concrete hardening with age – it seems to get harder for a period of several decades, then it begins to degrade. I’m not sure that the hardening is significant. Some concrete institute must have done along term study on this point.

Why does concrete get harder as it ages?

What is the difference between an Architect and an Architectural Designer?

Answer by Andrew Hawkins:

It really depends on the usage of the terms. But the most
likely distinction would be that an Architect has passed the registration exam.
A very rigorous exam administered by the NCARB. (some Architects use this as a
suffix to their name) This test is not one that measures design skill. It test
critical and technical knowledge related to the practice of architecture. The description
most often used is that the ARE tests a candidate’s knowledge to ensure health,
safety and welfare.

An architect is licensed by passing this test. It is very much the equivalent
to the Bar examination for the legal profession. The test is 7 parts and each
part ranges from 3-6 hours per test. Some take this exam over a period of time
(weeks to months). The passing rates for the exam are fairly low. (some section
in the 40% range) So to pass this test, you are required to be very knowledge
about much more than just architectural design. I would wager that most who
have passed this test would never call themselves an ‘”architectural
designer”. They have worked hard to achieve the title of
“Architect”. Someone who has passed this exam may have several
suffixes to their name:

AIA – Means they are a registered/ licensed architect who is a member of the
professional organization American Institute for Architects (aia.org)

RA – Means they are a registered/licensed architect. RA= Registered Architect.
They have passed the exam (may be a member of Society of American Registered
Architects, SARA)

NCARB – They are accredited by the National Council of Architectural Registration
Board. They have passed the exam and maintain their accreditation with NCARB

Now an “architectural designer” may have the exact same education,
training,  etc. as the above architect. But this person has not taken or
passed the registration exam. They cannot provide a set of “sealed”
documents that are required by many municipalities to get a building permit for
a construction project. They may have been in the architecture profession for
many, many years or just came into the profession and have a degree in design.
But they may not. The use of the terms architect and architecture are usually
well governed, but depending on your location, architectural designer may be
acceptable to describe someone with little to no architecture education. This
will vary by location.

All of this is not to say that an “architectural designer” is not
capable of doing a job as well as an “architect” but the designer has
not had to meet a certain set of qualifications and education to hold the title
of “architect”. And depending on your needs, both of these can
provide you with services. I, being a registered architect, would prefer
someone to select an “architect” for all their project needs.

What is the difference between an Architect and an Architectural Designer?

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Dear Readers ,

Today this blog is competing exactly 6 months from its inception.

We have 10,044 views and 152 followers to  the blog.

Want to express my sincere gratitude to all of you .

This blog is for YOU and you are my inspirations.

Thank you so much.

Santosh Kulkarni

What’s the difference between single span and multi-span reinforced concrete slabs?

Answer by Patrick Barry:

A ‘span’ in engineering parlance means ‘the gap between two supports’
This bridge is single span:

A single span slab is a slab that is supported at either end. And that’s it.

This bridge is (very) multi-span.

A multi-span slab has a support at either end and one or more additional supports in between.

BUT if the slabs on the above bridge were cut (see below) each becomes a single span slab. The bridge is then made of many many single spans that share supports.

^^  This is NOT continuous multi-span  ^^

Why do multispan slabs achieve greater spans?
Because they’re more efficient.

Let’s look at the Bending Moment Diagram (BMD) for a single span (simply supported) beam or slab. We generally design the slab to be able to resist the maximum Bending Moment, so it’s a very important value.
Looking at the diagram below, it’s zero at either end, and largest (most negative) in the center. Basically, it’s trying to bend downwards (sagging – something we’ve all seen with a fat man on a plank). If it breaks, it will break in the center.

Now let’s look at the bending moment diagram for continuous multi-span (simply supported) beam.

At the very ends, it looks a bit like a single span beam, but at all of the supports in the ‘middle’ section the bending moment is positive! This means in this area the beam is trying to bend the opposite way to the single span beam. (Imagine a chair with a plank balanced across it, and a fat man on either end).

If you look at the shape of the BMD curve between two supports, you can see it’s the same shape as for the single span, just ‘slid’ up the diagram vertically so some of it’s positive and the rest stays negative. This means the largest (most positive or most negative) value is actually smaller for the continuous multi-span section then the single span.
So for the same size span, the continuous span is stronger. Or, as you’ve found, for the same slab thickness, the continuous slab can span further safely.

Incidentally, if you’re doing this as a DIY project, please consult a civil/structural engineer. It’s not really something you can learn to do safely the first time from Quora, and if it goes wrong there won’t be a 2nd time.

What’s the difference between single span and multi-span reinforced concrete slabs?