Civil Engineering_Question and Answers_Part:2

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Civil Engineering_Question and Answers_Part:1

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 are freeway bridges built? After calculating the anticipated traffic for the bridge, cement/reinforced- with- rebar stanchions are spaced over the freeway to accommodate the bridge. An 'off-ramp' from the freeway to the bridge is constructed, as is an 'on-ramp' to the subsequent road. Cement/rebar slabs are built and lifted with cranes to form the platform, and voila! Drive carefully. Although the bridge deck/roadway is almost always a concrete slab, the structure that holds up the bridge deck can be reinforced concrete, structural steel, or a combination of steel and concrete.

4. 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. 

5. What is the difference between engineering stress and true stress? In biology, Stress is something that disrupts homeostasis of an organism. In engineering, Stress is an external force that pushes, pulls, twists, or otherwise puts force on something. Engineering stress assumes that the area a force is acting upon remains constant, true stress takes into account the reduction in area caused by the force.  

6. 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)

EEE_Question-Answers

    1.      How are the power correction capacitors available?

They are sold at a specific voltage rating by kVAR. They are sold in a trio of three capacitors. They are connected to induction motors and switched.

  2.      A star delta starter is used with induction motor. What is the reason behind it and mention its advantages?

The main advantage of using a star delta starter with induction motor is that the less amount of current can be made use of during the starting of the motor. Hence the current spent in total is also reduced.

3.      What is the use of a circuit breaker? Is it same as that of a fuse?

It is different from that of a fuse. It is used to reset the protective device. When heavy loads of input flows in, the fuse cuts of the internal connection and this breaker resets the protective device alerting it for safeguarding the entire unit.

4.      What can be the voltage gain of the voltage follower?

A voltage follower is a device whose output will merely just follow the input and hence won’t have any gain.

  5.      In power systems, what is the prime method that is followed to improve power quality?

A capacitor bank can be connected in series with the load which will result in the improvement of the overall power factor and power supply.

6.      Why are the transformers’ current measures in kVA? 

kVa is basically a unit that is used to measure apparent power which is a combination of active and reactive power. The transformer current generally includes the higher frequencies like the harmonics. Hence kVA is the easy way of measuring this type of current.

7.      What is known as regenerative breaking?

It is a general phenomenon that a motor continues running even after the power is cut off. This is due to the residual inertia. A load resistor is placed in the unit to prevent the motor from running after the power cut. The back e.m.f voltage is applied back across the resistor and due to this load the motor stops running. This entire mechanism is called as regenerative breaking.

  8.      Where is the output of an RC integrator taken across?

RC is a combination of resistor and capacitor. When load is applied across this unit, the output is obtained from the capacitor.

 9.      What is the two terminal voltage variable resistor popularly known as?

It is known as Rheostat.

10.  Why is DC flow of current blocked in a capacitor?

A capacitor’s reactance is inversely proportional to the frequency. For d.c. current there is no frequency and hence the reactance of the capacitor becomes infinite. This is the reason why a capacitor blocks DC.

11.  A humming sound occurs in the HT transmission. Why is that?

Ionization occurs due to the air break down in to the charged particles around the transmission conductors. This is the reason behind the humming sound and it is technically known as corona effect. In lay men terms it is a form of power loss.