Civil Engineering Technical Interview Questions

What is Civil Engineering?

A lot of students take up engineering, making it a popular field of study; one that is also very profitable. This scientific field of study is further divided into three primary segments: Electrical Engineering, Mechanical Engineering, and Civil Engineering.

Civil Engineering is one of the oldest applications of engineering. It deals with the planning, designing, and overseeing construction and maintenance of building structures and facilities, such as roads, railroads, airports, bridges, harbors, channels, dams, irrigation projects, pipelines, power plants, and water and sewage systems.

Additionally, civil engineering must ensure all of this, while also protecting health of the public and the environment health, so that these facilities add to it rather than deduct from it. Civil Engineering also focuses on improving existing infrastructures that may have been neglected.

What is the tallest man made structure in the world?

Human ingenuity is a marvelous thing. There is nothing in this world that can stop a person from achieving something that he has set his mind to. One such example is the tallest man made structure in the world.

The World’s tallest Man made building is the Burj Khalifa in Dubai, United Arab Emirates. It stands at 829.8 m (2,722 ft) tall and won the title of "Tallest Building in the World" and the tallest self-supported structure on January 9, 2010, when it first opened.

However, the tallest guyed structure is the KVLY-TV mast. It is located in North Dakota, United States, and stands at 2,063 ft (628.8 m) tall. It was the tallest structure until it was overtaken by the Burj Khalifa.

What are the causes of building collapse?

Things happen that can lead to disaster. While it is the job of a civil engineer to create structurally sound buildings, it does not meant that the building will always stay standing. Here are the main reasons that can lead to the collapse of a building:

  • The foundations are too weak – good foundation work is expensive, hence a builder might cut corners to save some costs which can result in the collapse of the building
  • Shoddy building materials – another place where a builder can cut costs is in the quality of materials used. If the quality is not up to mark, it may result in the collapse of the building.
  • Shoddy work – skilled workers also come expensive. Hence, it is not unlikely to get workers that do not have that much experience or so not know what they are doing. Alternately, even the most skilled workers can make mistakes.
  • Too much load – If a building is used for a purpose it is not designed, then it may collapse under the weight.
  • Passage of time – the passage of time wreaks havoc on everything, including building. As buildings get old, so the materials and its foundations making them more likely to collapse.
  • Natural Disasters - earth quakes, hurricanes, typhoons, soil liquefaction, etc. are just some of the acts of God that are lead to the collapse of a building.
What are the applications of modulus of elasticity?

The modulus of elasticity is also known as the elastic modulus, the tensile modulus, or Young's modulus. It is a ‘number that measures an object or substance's resistance to being deformed elastically when a force is applied to it’. Basically, it is a number that indicates how much force can an object take before it snaps or is no longer able to function at it is intended.

The modulus of elasticity should be calculated for all if not most materials that are used in construction. It is primarily used to test the quality of concrete or steel.

  • There are three main types of modulus of elasticity:
  • Young's modulus (E) which describes tensile elasticity
  • The shear modulus or modulus of rigidity which describes an object's tendency to shear
  • The bulk modulus (K) which describes volumetric elasticity

An example of the modulus of elasticity: the general Young's modulus (E) value of mild carbon steel is about 200 GPA as compared to about 70 GPA for aluminum. This means that aluminum is 3 times flexible than steel.

How do you measure concrete?

In order to properly construct something you need to have the right material and in the right quantities. However, while it is easier to calculate some materials, it is harder to calculate others, especially ones that require mixing such as concrete. There are a number of online conversion tool that help one calculate how much concrete they will need.

In order to measure concrete, one needs to measure the volume of the area. This can be done by multiplying the length, width, and height of the area that the concrete needs to be poured into. The volume of an area can be calculated in Cubic feet, Cubic yards, or Cubic Meter.

Here are the steps to measure concrete:

  • Measure the length, width, and height of the area.
  • Ensure they are in the same units. If not convert them.
  • Calculate the volume whose formula is: V= LxWxH, i.e. volume equals to length multiplied with width multiplied with height.
Which is stronger solid steel rod or hollow steel pipe?

Believe it or not, a hollow steel pipe is generally stronger than a solid steel rod, at least for two shafts of the same length and the same an equal weight of steel. Variations in length and type of steel will of course have an impact on the strength of the rod/pipe.

This is primarily due to the fact that most of the strength of a cylinder comes from its outer portion; hence even though it is hollow in the center it still has its strength. This results in a better strength to weight ratio for a hollow pipe than a solid rod. It also make the hollow pipe better apt to take more weight and is less likely to bend under that weight. A hollow steep pipe is also less likely to buckle in axial compression.

What is aggregate?

In civil engineering, an aggregate is the component of a composite material that is used to resist compressive stress.  

An aggregate is typically a granular material, and includes things such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag.

There are two different types of aggregates, natural and artificial. Both serve the same purpose which is help the composite material, such as concrete be stronger and achieve special strength. They also help increase the volume of concrete and hence reduce cost. They also help provide dimensional stability, as well as influence hardness, abrasion resistance, elastic modulus and other properties of concrete to make it more durable, strong and cheaper

How do you calculate the power of a centrifugal pump?

Power is required by every machine, in order to move and work. Similarly, the centrifugal pump also requires power to move and increase the pressure of a fluid. This power depends on a number of factors, including the pump and motor efficiency, the differential pressure and the fluid density, as well as the viscosity and flow rate.

The power of a centrifugal pump can be calculated via the following 3-phase power equation:

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

Alternately, the power required to operate the pump should be stated in Hp (horsepower) on the pump's nameplate.

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