Basic civil Questions | A to Z important Questions | 2021 | update know |

 1] Why steel reinforcement is used in RCC Structure ?

• Concrete is weak in tension .
• Coefficient of thermal expansion.

2] Why cover blocks are required ? what are their sizes ?

• Prevent exposure to atmosphere.
• Exposure can result in corrosion.

- Value of Cover :-

1. Footing : 50 mm
2. Chajah : 15mm
3. pile cap : 60mm
4. beam : 25mm
5. Stair : 15-25mm
6. pile : 60mm
7. column : 40mm
8. slab : 20mm

3] Why links and stirrups are used ? What Precautions should be taken ?

• beam have - Stirrups   and   column have - link or ties.
• Keep main reinforcement in position.
• Help in resisting shear forces.

4] What is unit wt. of different bars? and how it is calculated ?

• 8mm [8x8]/162=.395 kg/m
• 10mm[10x10]/162=.617kg/m
• 12mm[12x12]/162=.89kg/m
• 16mm[16x16]/162=1.6kg/m
• 20mm[20x20]/162=2.47kg/m
• 22mm[22x22]/162=2.98kg/m
• 25mm[25x25]/162=3.86kg/m
• 32mm[32x32]/162=6.32kg/m

  -  unit weight of bar :- volume x density 

  [(⺴/4) xD2 ] x 7850 kg/cum

 - Yield stress

• The Value of stress at yield point or at the yield strength.

5] What is lap or development length ? where and how it is provided ?

• Lap is provided to extend the reinforcement length.
• LD ( development length ) is additional length to join members at junction.

6] How many types of steel reinforcement ?

• FE - 250
• FE - 415
• FE - 415D
• FE - 500
• FE - 500D
• FE - 550
• FE - 550D
• FE - 600

FE : Iron   

500 : Yield stress in N/sq mm 

D : Ductility or elongation.