Monthly Archives: December 2014

annual report, blog, constructionqueries, readers

2014 in review

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Dear Readers ,

The year 2014 gifted me a precious gift ….YOU.

The word press team has just released the annual report for this blog.

[ Thank you so much …Word press for always standing up with me for support ]

You can also go through the report :

The WordPress.com stats helper monkeys prepared a 2014 annual report for this blog.

Here’s an excerpt:

A San Francisco cable car holds 60 people. This blog was viewed about 2,400 times in 2014. If it were a cable car, it would take about 40 trips to carry that many people.

Click here to see the complete report.

civil engg, construction, design, foundation, load distribution, RCC, structure

What a solid foundation..

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Overview:
Structural design of the foundations for a building is done by the structural designer of the project and is quite a specialized field within itself.
The construction personnel should be generally aware of the various requirements which a foundation has to fulfill.

This article explains the topic of foundation engineering from the execution point of view.

Basics of foundation design :

Structural Design is a balancing act between the disruptive and the stabilizing forces.

There are 3 elements in the foundation design.

A. The forces of nature :

A.1 Wind load :
Higher is the wind velocity higher is the wind pressure on the column which shall increase the turning moment on the footing .

A.2 Seismic loads :
Earthquake causes a lateral force to act on the footings and is parallel to the ground level.

The effect is similar to someone pulling the rug from under your feet.
Based on the past history of earth quakes and the geological data , seismological zones have been defined. The relevant seismic coefficient is taken into consideration   making provision for the destabilizing forces due to earthquakes.

A.3 Subsoil water pressure :
The upward pressure of the sub soil water tends to destabilize the footing by uplifting.
This needs to be counterbalanced properly.

B. The character of the soil :

B.1 Topography :
Building code specifies that the footing must rest to a depth of minimum 900 mm from the natural ground level.

B.2  Strata at various depths:
The type of strata decides the Bearing capacity .
Safe bearing capacity is the ability to sustain that load while keeping the settlement within permissible limits.

C. The character of building :
The elements which have a direct bearing on the design of footing are :

C.1: Height of building :
More is the height of building , more is the loads transferred by the column to the footing and it is designed .

C.2: Column span :
The distance between two adjacent columns :
C.2.1 : Determine the bending moments  at the joints  which affect the foundation design.

C.2.2 : Decides whether to go for isolated column footings or combined footing.

C.3 : Loading conditions on the columns :
Whether load axis is symmetric or eccentric also has an effect on the design.

C.3.1 Dead loads :

Determined from the density of the various materials used for the construction .

RCC : 2500 Kg / CuM.
Red bricks : 1600 Kg / CuM.
AAC blocks : 600 Kg / CuM.

C.3.2 Live loads or superimposed loads:

For a residential building , this is to be considered for a minimum of
200 Kg / Sq.M .

D : Other considerations :
D.2 For end columns of a building it may not be some times possible to excavate a regular footing since it may project into the adjoining property.
At such times it is suggested to have a she footing.

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construction, drains, protection, strom water, undeground

What are some of Tokyo’s very well kept secrets?

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Readers ,
Such an fascinating story of the storm water drains in Tokyo.
You shall also be thrilled to see the stunning sketches.
Just enjoy !

Answer by A Quora admin:

Tokyo is protected against flood by gigantic constructions under the ground.

They are invisible in our daily life, but they sure help us to remain safe when Tokyo is hit by torrential rain.

One such example is the Kanda River Underground Retention Basin made up of 4.5 km tunnel 40 meters under the ground.

This underground retention basin can hold up to 540,000 tons of water when Tokyo is hit by flood.

Another example is the Metropolitan Area Outer Underground Discharge Channel.

This is a complex of five vertical shafts of 30 meters in diameter and 70 meters in depth, which are connected each other by tunnels of 10 meters in diameter and 6.3 kilo meters long, all told.

This is actually located in Saitama prefecture, but it was constructed to protect broad area of Kanto including Tokyo.

Each vertical shaft is as huge as space shuttle.

At the end of the channel, there is the symbolic place called ‘pressure-adjusting tank’ also known as ‘Underground Parthenon’ which is as large as a soccer ground and measures 18 meters in height.

These facilities accept a study tour.
It might be a good idea to visit and see how they work, when you have the time.

What are some of Tokyo’s very well kept secrets?

Uncategorized

What is a twisted steel bar?

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Reader ,
We normally use the Ribbed bars in the RCC work .
This article gives information on the history of these bars .
Quite interesting article.

Answer by A Quora admin:

In the US, this was an antiquated form of reinforcing that predates modern rebar. The mechanical interlock between steel and concrete is critical in reinforced concrete. Early concrete reinforcing was sometimes smooth and square. This shape did not create much friction to make a solid interlock. One solution to this problem was to twist the bar like a corkscrew with creates many teeth for a strong mechanical lock. The primary drawback to doing this is that the twisting causes the steel to work harden and become more brittle.

Here is a patent image for a twisted steel reinforcing bar, from 1884.

What is a twisted steel bar?