FACTS ABOUT DAM

• A dam is a barrier designed and constructed to contain the flow of water. It is often built in conjunction with a hydroelectric power station to provide electricity.
  
  
• Dams are built for purposes such as generating hydroelectricity, creating recreational areas, minimizing flood risks, diverting water for irrigation, and providing water for towns and cities.
  
  
• The type of dam built in any given situation depends on factors such as the intended purpose, environmental considerations, available finances and the location.
  
  
• Different types of dams include masonry dams, embankment dams and arch-gravity dams.
  
• Beavers create their own dams from sticks and mud as protection from predators and also to help provide easy access to food.
  
  
• Dams are huge engineering projects that require vast financial resources. For example, the construction of the Itaipu Dam on the border of Brazil and Paraguay (completed in 1984) cost around US$20 billion.
  
  
• Built along the Colorado River between 1931 and 1936, The Hoover Dam reaches 726 feet in height (221 metres).
  
  
• When the Hoover Dam was completed it was both the world’s largest concrete structure and largest hydroelectric power station.
  
  
• The Hoover Dam is made of enough concrete to make a two lane highway from New York to San Francisco, that’s around 4000 miles (2500 kilometres).
  
  
• As of 2010, the tallest dam in the world is Nurek Dam in Tajikistan. Completed in 1980, it reaches 300 metres (984 feet) in height.
  
  
• Many dam failures have occurred in the past, these disasters can cause significant damage and threaten lives.
  
  
• In 1889 a failure of the South Fork Dam near Johnstown, Pennsylvania, USA, killed over 2200 people.
  
  
• In 1975, the Banqiao Dam in China was among many dams that were destroyed after the extreme rains of Typhoon Nina. It is estimated that between 90000 and 230000 lives were lost as a result of the Banqiao Dam breaking.
  

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Test for Bricks:

(1) Absorption:

A brick is taken and it is weighed dry. It is then immersed in water for a period of 16 hours. It is weighed again and the difference in weight indicates the amount of water absorbed by the brick. It should not in exceed 20 per cent of weight of dry brick.

(2) Compressive/Crushing strength of Bricks:

The crushing strength of a brick is found out by placing it in a compression testing machine. It is pressed till it breaks.  the minimum crushing or compressive strength of bricks is 3.50 N/mm2. 

The bricks with crushing strength in between of 7 N/mm2 to 14 N/mm2 are graded as A and those having above 14 N/mm2 are graded as AA, 

(3) Hardness test on bricks:

In this test, a scratch is made on brick surface with the help of a finger nail. If no impression is left on the surface, the brick is r sufficiently hard.

(4) Presence of soluble salts:

The soluble salts, if present in cause efflorescence on the surface of bricks. For finding out the presence of soluble salts in a brick, it is immersed in water for 24 hours. It is then taken out and allowed to dry in shade. The absence of grey or white deposits on indicates absence of soluble salts.

If the white deposits cover about 10 per cent surface, the efflorescence is said to be slight and it is considered as moderate, when the white deposits cover about 50 per cent of surface. If grey or white deposits are found on more than 50 per cent of surface, the efflorescence becomes heavy and it is treated as serious, when such deposits are converted into powdery mass.

(5) Shape and size:

In this test, a brick is closely inspected. It should be of standard size and its shape should be truly rectangular with sharp edges. For this purpose, 20 bricks of standard size (190 mm x 90 mm x 90 mm) are selected at random and they are stacked lengthwise, along the width and along the height.

(6) Soundness test on brick:

In this test, the two bricks are taken and they are struck with each other. 
The bricks should not break and a clear ringing sound should be produced.

Other test can be perform but these 6 are the important once.

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BASICS OF CIVIL ENGINEERING

 CLICK HERE TO DOWNLOAD===>>> BASICS OF CIVIL ENGINEERING

1. INTRODUCTION 

2. CLASSIFICATION OF SKELEAL
OR FRAMED STRUCTURES 

3. INTERNAL LOADS DEVELOPED IN
STRUCTURAL MEMBERS 

4. TYPES OF STRUCTURAL LOADS 

5. DTERMINATE AND INDETERMINATE 
 STRUCTURAL SYSTEMS

6. INDETERMINACY OF STRUCTURAL SYSTEM 

7. FLEXIBILITY AND STIFFNESS METHODS 

8. ANALYSIS OF STATICALLY DETERMINATE
STRUCTURES 

9. ANALYSIS OF DETERMINATE TRUSSES 

10. CABLES AND ARCHES 

11. INFLUENCE LINES FOR DETERMINATE
STRUCTURES 

12. DEFLECTION OF STRUCTURES 

13. NONPRISMATIC MEMBERS

14. SLOPE DEFLECTION EQUATIONS

15. MOMENT DISTRIBUTION METHOD

16. ANALYSIS OF CONTINUOUS BEAMS AND
PLANE FRAMES CONSISTING OF PRISMATIC
AND NONPRISMATIC MEMBERS

17. ANALYSIS OF INDETERMINATE TRUSSES 

18. APPROXIMATE METHODS OF ANALYSIS OF
STATICALLY INDETERMINATE STRUCTURES

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TRUSS TYPES

                                                         

                                                                 Modified-Queen-Scissors

                                                         Baby Barn and Shed Trusses

                                                                       floor truss

                                                                  attic-common truss

                                                                     

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Basics of Truss

In the above picture u can see a beam and truss, the vertical member in truss is similar to stirrup in beam and compression member in truss is similar to concrete between the stirrups. you are aware that concrete is good at compression and steel is good at tension, thus the combination of both counters the shear force.

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