Category Archives: buildings

HAT-TRICK OF ESTIMATION

FRIENDS ,

You deserve a vote of THANKS for your great contributions.

Look at this :

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Your blog has again created a new record of 532 Views on 10th March 2016.

Today , we are going to do a new estimate.

This is also being done in FPS units for the purpose of practice.

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Now let us start the estimate.

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Now you shall need the formula for the trapezoidal portion :

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Now its time to prepare an Abstract of all items :

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My God..You are Cranked !

Friends ,

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You shall certainly feel that I have become cranked after seeing this post which is again on Bar bending schedule. But this time , we are going to learn how to calculate the cutting length of the BENT UP BAR which is also known as CRANKED BAR  

[ By the way , this is sometimes referred as the Flexural steel ].

The following example shall give you clarity on the Bent up bars.

But before we take up the example, let me give you a simple formula for calculating the cutting length of the bent up bar.

By this time, you already know that in Beam , there are 2 bent ups per bar whereas in a slab , there is only one bent up per bar.

Just see the following sketch :

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Now write down the following formula :

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Some students have asked me what is the logic behind this factor 0.41 H.

The logic can be found by applying the famous right angle formula by Pythagoras.

Still if you are not able to find out , we shall study in a separate article. OK ?

Now , let us solve the following question using this formula :

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Try to find out the cutting length YOURSELVES through the application of the formula.

Check your answer in the following sheet :

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Hope you have enjoyed this exercise.

Thank you !

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Form work for Curved beams

Curved beams :

Prologue :

The centering and shuttering of the curved beams does provide a different challenge as compared to the normal beams. This article attempts to identify the key steps in undertaking the curved beam form work with prefection.

Types of curved beams :
There could be two types of curved beams :
1. Curved in plan :
This could be either a circular beam or a arc beam either for the water tank or for the roof of a building.
2.Curved in elevation:
Mostly for the ornamental window lintels which are arch shaped beams.
3.Composite ( curved in Plan and elevation both ): Very typical folded structure which is circular in plan and also undulating in level on the circumference.

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 are some of the most magnificent structures ever constructed by humans?

Answer by Ratnakar Sadasyula:

The Brihadeeswara Temple in Tanjore, India is an awesome feat of engineering. The top of the temple contains a single block of stone, also called as the kalasam, weighing around 50 tons. It  was believed that a ramp was constructed to transport the block to the top, using elephants. It is also astounding to note that the temple is more than 1000 years old.

The Kailashnatha Temple in Ellora, Maharashtra, has to be one of the greatest feats of engineering ever.  Carved out of  a single stone, the temple is unique for it’s top down construction feat.  The sculptors, engineers started at the top of the rock and then carved their way straight down,  making the temple out of the rock.

The Sun Temple in Konark, representing the Sun drawn in the form of a chariot, with horses, constructed in such a way, that the Sun rays fall right on the sanctum sanctorum at sunrise.

The Daulatabad Fort now mostly in ruins, but had one of the most elaborate security systems, with cannons, booby traps, dead turns, mazes.

The Golkonda Fort, near Hyderabad, with a  highly advanced accoustics system, where you could clap at the entrance of the fort, and it would be heard all the way up to the king.

The Gol Gumbaz at Bijapur, famed for it’s Whispering Gallery, again another great feat of accoustical engineering.

The Konkan Railway read it up here  http://en.wikipedia.org/wiki/Konkan_Railway

What are some of the most magnificent structures ever constructed by humans?

You don’t like the AAC  blocks ? 

Overview:

During the previous posts , we had a review of the brick masonry ,stone masonry and then also went on to enjoy some basic estimation in brick work.

While speaking of masonry , the name of AAC blocks invariably comes in the picture .Some people also

The C4X blocks were invented in Sweden in the year 1920 and then extensively used in European countries till recent years. For Asian countries, the phase has just begun and we are  witnessing a rapid replacement of the traditional red clay bricks to the  AAC blocks.

This article explains  the pros and cons of using AAC blocks in your next project.

The blocks in brief:
Material:
The auto-claved aerated concrete blocks are made from Quartz sand, calcinated  gypsum, lime, and/or cement, aluminium powder and water , fly ash and ferrous oxide. Or to simplify , the composition is Cement, Fly Ash Sand & Aeration Compound
Sizes:
Normal dimensions are:
Length: 625 mm. Height: 240 mm.
Thickness: 50 mm. ,75 mm. ,100 mm.,150 mm. , 200 mm. & 300 mm.

Which size to use ?

Many combinations can be worked out depending on specific needs.

Normally, the external walls are made with 150 mm thick blocks whereas for internal walls ,100 mm thick blocks are used. the architectural features such as fins or Cavity walls are made with 50 mm or 75 mm thick walls.

What are the basic advantages ?

1.Light weight :
The  micro structure is porous which makes it lighter (600 Kg/CuM) than the red clay bricks ( 1900 Kg/CuM) and much lighter than conventional concrete ( 2500 Kg/CuM) which directly implies :

1.1 Reduced dead loads due to masonry on beams ,columns and footings. This results in lowered RCC sizes and hence reduced costing.

1.2. For masons the handling is easier .

1.3 Due to its larger size, no of blocks to be handled per CuM of AAC masonry is much smaller than Brick work. [ Only 67 AAC blocks of size 625 mm x 240 mm x 200 mm are needed for 1 CuM whereas for same volume of brick masonry , the mason has to handle 514 bricks.]

2.Conserves environment:
It does not need the clay and hence the fertile soil from the green fields is not wasted.
3.Better properties:
3.1.Sound insulation
3.2.Thermal efficiency
3.3. Lesser piece to piece variation

lower environmental impact as:

Improved thermal efficiency reduces the heating and cooling load in buildings.
Resource efficiency
Light weight saves cost & energy in transportation, labor expenses, and increases chances of survival during seismic activity.

4. Yes, it does reduce the RCC as well as steel sizes as its density is pretty lower as compared.  Requirement of mortar for laying AAC blocks is reduced due to less number of joints. Similarly material required for rendering is also lower due to dimensional accuracy of AAC.

Author’ s note :

Let me put on records my sincere appreciations for Ms.Rakshita who answered to my questions about AAC blocks .You can refer to the question and answer at this link .