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

1. For a rectangular beam, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11. What is the critical neutral axis depth factor(k)?

a) .38

b) .48

c) .58

d) .28

View Answer

Explanation: k=1/(1+r/m) [r=t/c=140/5=28]

=1/(1+28/11)=.2824

2. For a rectangular beam of 300*600mm^{2}, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11. What is the depth of the neutral axis?

a) 170mm

b) 270mm

c) 370mm

d) 470mm

View Answer

Explanation: k=1/(1+r/m) [r=t/c=140/5=28] =1/(1+28/11)=.2824;

n=kd=.2824*600mm=169.44mm.

3. What is the modular ratio of a concrete of M20 grade reinforced with Fe250 steel?

a) 11

b) 9

c) 13

d) 3

View Answer

Explanation: According to codal provision, m=280/(3*Ϭcbc)

Ϭ

_{cbc}is 7 for M 20 grade concrete; m=13.3333

4. What is the critical neutral axis depth factor for Fe250 reinforced M20 grade concrete?

a) .40

b) .50

c) .60

d) .70

View Answer

Explanation: IS 456:200 gives critical neutral axis depth factor k= 1/(1+.0107 Ϭ

_{st}) [Ϭ

_{st}=140MPa]

=1/(1+ .0107*140)=.40

5. If the modular ratio and percentage of steel is known, the neutral axis factor can be determined.

a) False

b) True

View Answer

Explanation: According to the codal provision the neutral axis factor is dependent on the modular ratio m and percentage of steel p.

k=[2mp+(mp)

^{2}]

^{1/2}-mp; this is the desired equation to determine the neutral axis factor.

6. What is the percentage of steel (p) for Fe250 reinforced M20 grade concrete?

a) .98

b) .48

c) .58

d) .39

View Answer

Explanation: p=50m Ϭ

_{cbc}2/ Ϭ

_{st}(m Ϭ

_{cbc}+Ϭ

_{st})=.98 [m=13; Ϭ

_{cbc}=7MPa; Ϭ

_{cbc}=140MPa]

7. For a rectangular beam of 300*600mm^{2}, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11. What is the lever arm factor?

a) .81

b) .71

c) .91

d) .61

View Answer

Explanation: According to codal provision,

k=1/(1+r/m) r=t/c=140/5=28]

=1/(1+28/11)=.2824

j=1-k/3=.9058=.91

8. For a rectangular beam of 300*600mm^{2}, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11. What is the depth of lever arm?

a) 346mm

b) 546mm

c) 646mm

d) 746mm

View Answer

Explanation: According to codal provision,

k=1/(1+r/m) [r=t/c=140/5=28]

=1/(1+28/11)=.2824

j=1-k/3=.9058=.91

a=jd=.91*600=546mm

9. For a rectangular beam of 300*600mm^{2}, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11. What is the stress ratio?

a) 38

b) 28

c) 48

d) 58

View Answer

Explanation: r=t/c=140/5=28

10. For a rectangular beam of 300*600mm^{2}, the permissible stress of concrete and steel are 140MPa(t) and 5MPa(c) and modular ratio 11.What is the area of reinforcement if it is subjected to 20kNm moment?

a) 281.64mm^{2}.

b) 211.64mm^{2}.

c) 261.64mm^{2}.

d) 221.64mm^{2}.

View Answer

Explanation: According to codal provision,

k=1/(1+r/m) [r=t/c=140/5=28] =1/(1+28/11)=.2824

j=1-k/3=.9058=.91

a=jd=.91*600=546mm

Area of steel is= M/t*a=261.64mm

^{2}.

**Sanfoundry Global Education & Learning Series – Design of RC Structures**

To practice all areas of Design of RC Structures, __ here is complete set of 1000+ Multiple Choice Questions and Answers__.

**If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]**