Interview Related Questions & Answers Part-IV

1. What are the causes of building collapse?

The PAssage of time is one reason. Buildings also collapse due to weak foundations. Earthquakes, hurricanes and other natural disasters can also damage the structure of the buildings and cause it to collapse. Bombings or demolition of buildings is also other reasons.

 

2. What are the applications of modulus of elasticity?

As the term implies, "Modulus of Elasticity” relates to the elasticity or "flexibility" of a material. The value of modulus of elasticity is very much significant relating to deflection of certain materials used in the construction industry. Take for example the general E value of mild carbon steel is about 200 GPA comPAred to about 70 GPA for aluminum. This simply translate that aluminum is 3 times flexible than steel.

 

3. How do you measure concrete?

Cubic feet, Cubic yards, Cubic Meter

 

4. Which is stronger solid steel rod or hollow steel pipe?

On a per pound basis, steel pipe is stronger in bending and is less likely to buckle in axial compression.

 

5. What is aggregate?

Aggregate is the component of a composite material used to resist compressive stress.

 

6. How do you calculate the power of a centrifugal pump?

The input power, that is, the power required to operate the pump should be stated in Hp (horsepower) on the pump's nameplate. It can also be calculated by the 3-phase power equation:

P(in Hp) = VI(1.7c) = Rated Voltage x Rated Current x 1.73/ %Efficiency

If this is a consumer grade pump that operates on 120Vac, then the equation becomes P = VI, simply multiply the operating voltage, 120 x current (which is the number followed by the letter "A".The output power, which really is not technically power, but rated in Gpm (gallons per minute), or caPAcity should also be on the nameplate. If you have the make, model, and (not necessarily needed) the serial number (also on the nameplate) you could call the manufacturer's customer service dept. As an application engineer, I have contacted countless manufacturers’, and service dept's for assistance. It is now big deal to them, they will be happy to answer your questions.

 

7. What is rigging?

In sailing, the ropes used to move the sails around so the boat will move in the right direction when the wind blows.

 

8. What is absolute pressure?

Absolute pressure is simply the addition of the observed gage pressure plus the value of the local atmospheric pressure.

 

9. How do we calculate absolute pressure?

Absolute is equal to gauge pressure plus atmospheric.

 

10. What is Gravity flow?

Gravity flow is fluid flowing due to the forces of gravity alone and not to an applied pressure head. In the Bernoulli equation, the pressure term is omitted, and the height and velocity terms are the only ones included.

11. What do you mean by honeycomb in concrete?

Some people call it an air pocket in the concrete or a void. It is the exposed course aggregates on surface of concrete without covered by mortar or surrounding the aggregate particles.

 

12. What is the purpose of the gap in the road on this bridge?

Purpose of the gap in the road is to allow the road to exPAnd and contract with temperature changes without causing damage or deformation to the road.

 

13. What is a projection line?

Projection line is the way, in which the earth is shown on a flat piece of Paper.

 

14. What are moment of inertia and its importance in civil engineering?

The moment of inertia measures the opposition any kind of body will have against a certain momentum (along that same axis) trying to rotate that body.

 

15. What is the absolute pressure scale?

Absolute pressure is calculated from a vacuum (0 PSI) and atmospheric pressure is14.7PSIa or 14.7 PSI above a vacuum 1PSI on a tire pressure gauge is called 1PSIg = 15.7PSIa 10PSIg=24.7PSIa 100PSIg=114.7PSIa etc.

 

16. What is diversion tunnel in a dam?

When a dam is to be built, a diversion tunnel is usually bored through solid rock next to the dam site to byPAss the dam construction site. The dam is built while the river flows through the diversion tunnel.

 

17. How do you maintain water pressure?

If you have water pressure and wish to maintain it, do not cause flow in the line, which will reduce pressure due to friction. To keep pressure up, reduce friction by increasing the line size or eliminating some other restriction.

 

18. What are some structures that may be subjected to fatigue?

Bridges, hydraulic presses, burners trains

 

19. Why does the pressure increase under soil?

Soil pressure increases with depth due to the overburden or self-weight of the soil and due to loads imposed upon the soil.
For example, the pressure variation below the depth of soil is linear and the relation is given by pressure = unit wt * depth. As depth increases, there will be a linear increase in the soil pressure.

 20.

Lap Length of Reinforcement Bars

Lap length is the overlapping length of two reinforcement bars. Reinforcement steel is available from 6 to 18 meters. If we need to extend beyond that, we are connecting it with another steel bar. That overlapping length is nothing but Lap Length.

Example:-

The diameter of bar is 28 mm,
Lap Length = 50 x 28
                  = 1400 mm
                  = 1400/1000 = 1.4 m

21. How do you measure concrete? 
Cubic feet, Cubic yards, Cubic Meter


22. Which is stronger solid steel rod or hollow steel pipe? 
On a per pound basis, steel pipe is stronger in bending and is less likely to buckle in axial compression.

23. What is the tallest man made structure in the world? 
The tallest man made structure is the KVLY-TV mast which is 2063 feet tall. The worlds tallest man made structure is Burj Dubai which is 800 meter tall.

24. What is braced excavation all about? 
Excavations are braced to prevent the cave-in of surrounding unstable soil.

25. What is the meaning of soil reinforcement? 
Soil reinforcement is the act of improving soil strength to enable it support or carry more load.

Two common examples are:

a) Mixing a soil amendment such as lime into weak clayey soil and re-comPActing to improve soil-bearing caPAcity (often done under the road base in highway construction)

b) Installing plastic or composite webbing layers (called geo-grid material) alternating with comPActed soil to produce a stronger sloped soil structure (often done on steep roadway embankments to improve strength and stability)

26. What is aggregate? 
Aggregate is the component of a composite material used to resist compressive stress.
                                                      or

Aggregate is Inert Material use in Making of Concrete.
27. What year was the keystone power plant in Indiana County constructed? 
1967 began commercial operation on unit 1.

28. What are the uses of alloys in daily life and how are alloys made? 

Alloying is not always done to produce a 'superior' material, but to produce materials having a desired requirement in the industry or elsewhere. A classic case is of lead solder (containing lead & tin), in which the melting point of the constituent elements are lowered, not necessarily a desirable property.

Alloying can be carried out using hot press method (a sheet of material is sandwiched with alloying material), rolling the heated base metal in a drum full of alloying metal powder, using hot spraying, galvanizing (dipping the base in a molten solution of alloying material) etc. Sometimes the alloying material is added in small proportions to the molten base metal (e.g., in production of different types of steel).

29. What is the worlds largest concrete dam?The Grand Coulee Dam is said to be the largest concrete dam. Currently the world's largest concrete dam is the Itaipu Dam, an accomplishment of two neighboring countries, Brazil and Paraguay in South America.

Though it is not finished yet, the Three Gorges (or Sandapong) Dam on the Yangtze River in China will take over as the largest upon its completion, which is slated for 2009.