Design of RC Structures Questions and Answers – Foundations

This set of Design of RC Structures Multiple Choice Questions & Answers (MCQs) focuses on “Foundations”.

1. Which of the following are the two main portions of a structure?
a) Foundation and footing
b) The superstructure and the substructure
c) Columns and beams
d) Slab and beams

Explanation: A structure is generally considered to have two main portions namely the superstructure and the substructure. The substructure transmits the loads from the superstructure to the supporting soil and is generally termed as foundation.

2. What is the objective of providing foundation to a structure?
a) To provide a base to the structure
b) To stabilize the soil below the structure
c) To distribute the load to the soil
d) For the compaction of the soil below the structure

Explanation: The objective of providing foundation to a structure is to distribute the load to the soil. It should be such that the maximum pressure on the soil is in its permissible bearing value. At the same time the settlement is within the permissible limits.

3. Which of the following are the two heads of foundation?
a) Pier and pile
b) Strip and strap
c) Shallow and deep
d) Combined and raft

Explanation: Foundations are of two types: shallow foundation and deep foundation. The foundation is shallow if its depth is equal to or lesser than its width. In case of deep foundation, the depth is greater than the width.

4. Which of the following is not a shallow foundation?
a) Pier foundation
c) Raft footing
d) Strap footing

Explanation: The types of shallow foundation are: Spread footing, strap footing, combined footing and mat or raft footing. Types of deep foundation are strip, rectangular or square foundations. Some common forms of deep foundations are pier foundation, pile foundation and well foundation.

5. Which type of footing can transmit the load of an isolated column or a wall on the subsoil?
a) Combined
b) Mat or raft
d) Strap or cantilever

Explanation: A spread footing is a type of shallow foundation. It transmits the load of an isolated column, or that of a wall on the subsoil. For the walls, the footing is continuous and for columns, it is isolated footing.

6. Combined footing is provided when the footings are close to each other.
a) False
b) True

Explanation: When a spread footing supports two or more columns it is combined footing. Combined footing is installed when the individual footings are either close to each other or overlap. These footings can be rectangular or trapezoidal.

7. The strap beam of the strap footing remains in contact of the soil and transfers pressure to the soil.
a) True
b) False

Explanation: A strap footing consists of spread footings of two columns connected by a strap beam. The strap beam and soil are not in contact so no pressure transfers to the soil. These footings combine the footing of outer column to the adjacent one.

8. Which footing is relevant when the available soil pressure is low or the building loads are heavy?
a) Mat or raft
b) Strap
c) Combined

Explanation: A mat or raft is a combined footing that covers the entire area beneath a structure and supports all the walls and columns. If the available soil pressure is low or the building loads are heavy, spread footings will cover one – half of the area. It may prove economical to use mat or raft foundation.

9. Pile foundation is a deep foundation used when the top soil is relatively weak.
a) True
b) False

Explanation: Pile foundation is a deep foundation used where the top soil is relatively weak. It is the most common type of foundation used for buildings. Here a group of piles transfer the load of the super- structure to the sub – soil.

10. Which type of foundation transfers the load to a stratum of greater bearing capacity?
a) Pile foundation
b) Mat or raft foundation
d) Combined footing

Explanation: Piles transfer the load to a lower stratum of greater bearing capacity by end bearing. Piles transfer the load to the intermediate soil through skin friction. The pile foundation is suitable for relatively soft soils.

Sanfoundry Global Education & Learning Series – Design of RC Structures

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