# Design of RC Structures Questions and Answers – Doubly Reinforced Beams

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

1. Where are the doubly reinforced beams required?
a) Where depth of the beam is restricted
b) Where width of the beam is restricted
c) Where concrete amount is restricted
d) Where high strength is required

Explanation: Beams reinforced with steel in both compression and tensions are called doubly reinforced beams. They are used where architectural consideration of depth is restricted.

2. The moment of resistance can be increased by not more than ____ % over the balanced section.
a) 10%
b) 15%
c) 20%
d) 25%

Explanation: The moment of resistance can be increased by not more than 25% over the balanced moment of resistance, by making the beam over reinforced on the tension side.

3. Select the incorrect statement for the following.
Doubly reinforced beam is used in the following circumstances.
a) The external live loads may alternate
c) The members may be subjected to a shock
d) The members may need high compressive strength.

Explanation: e.g. A pile may be lifted in such a manner that the tension and compression zone may alternate.

4. After curing concrete for 28 days, how much strength will it attain?
a) 10-20%
b) 20-50%
c) 50-80%
d) 90-95%

Explanation: Normally concrete is cured for 28 days to check its compressibility because it attains of about 90-95% of its strength in that period.

5. When was the ultimate load method of designing evolved.
a) 1940
b) 1950
c) 1960
d) 1970

Explanation: The ultimate load method of designing was evolved in 1950 and became an alternative to WSM. It is also referred as load factor method.

6. Ultimate limit state deals with discomfort to occupancy caused by excessive deflection.
a) True
b) False

Explanation: Ultimate limit state deals with strength, overturning, sliding, fatigue etc.

7. What is the modular ratio for M50 grade concrete?
a) 7.18
b) 6.44
c) 5.83
d) 18.67

Explanation: m = 280/3σcbc
σcbc for M50 = 16
So, m = 5.83

8. WSM assumes that structural steel behaves in _____ manner.
a) Linear elastic
b) Plastic
c) Flexural
d) Permissible

Explanation: Working Stress method is based on linear elastic theory which is used for reinforced concrete and structural steel.

9. Which of the following is the undesirable compound for the concrete?
a) C3S
b) C2S
c) C3A
d) C4AF

Explanation: The hydration rate of C3S is accelerated in the presence of limestone probably because of the dilute effect and the multiplied nucleation sites that is why it is not required in concrete.

10. Whit cement in doubly reinforced beam contains less amount of ________
a) Lime
b) Silica
c) Alumina
d) Iron Oxide

Explanation: Iron oxide is creates a chemical bond with steel and starts reacting to form a undesirable compound that is why, it is in very less quantity in white cement.

Sanfoundry Global Education & Learning Series – Design of RC Structures

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