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*600mm2, 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)
Ϭcbc 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 Ϭst) [Ϭst=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 Ϭcbc2/ Ϭst(m Ϭcbc+Ϭst)=.98 [m=13; Ϭcbc =7MPa; Ϭcbc=140MPa]
7. For a rectangular beam of 300*600mm2, 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*600mm2, 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*600mm2, 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*600mm2, 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) 281.64mm2.
b) 211.64mm2.
c) 261.64mm2.
d) 221.64mm2.
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=261.64mm2.
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.
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