Development Length

Q. The development length in compression for a 20 mm diameter deformed bar of grade Fe 415 embedded in concrete of grade M 25 whose design bond stress is 1.40 N/mm${}^2$, is

1. 1489mm
2. 1289 mm
3. 806 mm
4. 645 mm

Q. In limit state design, permissible bond stress in the case of deformed bars is more than that in plain bars by

1. 60%
2. 50%
3. 40%
4. 25%

Q. Lap length of reinforcement in compression shall not be less than

Where $\varphi$ = diameter of bar.

1. $30\varphi$
2. $24\varphi$
3. $20\varphi$
4. $15\varphi$

Q. What is the bond stress acting parallel to the reinforcement on the interface between bar and concrete?

1. Shear stress
2. Local stress
3. Flexural stress
4. Bearing stress

Q. Assertion (A): The development length for HYSD Fe 415 bars is less than that for mild steel plain bars.

Reason (R) : The permissible bond stress for HYSD Fe 415 bars is more than that for mild steel plain bars.

1. both A and R are true and R is the correct explanation of A
2. both A and Rare true but R is not a correct explanation of A
3. A is true but R is false
4. A is false but R is true

Q. The bond between steel and concrete is mainly due to
1. Mechanical resistance
2. Pure adhesive resistance
3. Frictional resistance

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

Q. Assertion (A) : Tensile reinforcement bars of a rectangular beam are bent at suitable places.
Reason (R) : Bent tensile reinforcement bars in a rectangular beam resist bending moment and provide local bond stress

1. A and R both are true and R is the correct explanation of A
2. A and R is true But R is not the correct explanation of A
3. A is true and R is false
4. A is false but R is true

Q. Consider the following statements:
1. At a point of inflection, the embedment length
need not exceed the development length L${}_{\sigma }$

2. The condition that $L_{\sigma }(\frac{M_1}{V}+L_0)$ need not be checked for negative reinforcement.

At least one-third of the total negative
reinforcement provided must extend beyond
the point of inflection for a distance not less
than 'd' or 12$\varphi$ or clear-span whichever is
larger.

Which of these statements are correct?

1. 1, 2 and 3
2. 1 and 2
3. 1 and 3
4. 2 and 3

Q. Which of the following statements are correct?

1. Splices in flexural members should not be at sections where the BM is more than 50% of the moment of resistance.
2. Normal lap splices can be used for all types of bars irrespective of the sizes.
3. Where bars of two different diameters are to be spliced, the lap length shall be calculated on the basis of the diameter of the smaller bar.

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

Q. When HYSD bars are used in place of mild steel bars in a beam, the bond strength

1. does not change
2. increases
3. decreases
4. becomes zero

Q. In a reinforced concrete member, the best way to ensure adequate bond is

1. to provide minimum number of large diameter bars
2. to provide large number of smaller diameter bars
3. to increase the cover for reinforcement
4. to provide additional stirrups

Q. If a beam is likely to fail due to high bonding stresses, then its bond strength can be increased most economically by

1. Providing vertical stirrups
2. Increasing the depth of the beam
3. Using smaller diameter bars in correspondingly more numbers
4. Using higher diameter bars by reducing their numbers

Q. The appropriate expression in assessing development length is

1. $L_d=\frac{\varphi {\sigma }_s}{4{\tau }_{bd}}$
2. $L_d=\frac{\varphi {\sigma }_{bc}}{{\tau }_{bd}}$
3. $L_d=\frac{{\sigma }_s}{4{\tau }_{bd}}$
4. $L_d=\frac{\varphi {\sigma }_s}{8{\tau }_{bd}}$

Q. A fillet weld is simultaneously subjected to factored normal and shear stress of 120 MPa and 50 MPa, respectively. As per IS 800:2007, the equivalent stress (in MPa) is _______.

Q. Consider the following statements:
Bars that extend into a simple support must be able to develop their full strength at a designated point L so that their moment capacity is more than the bending moment at that point. The clauses of the code require that $({\sigma }_s=0.85{\sigma }_{sy})$

1. $L_d\le \frac{1.3M_1}{V}+L_0$

2. $\frac{\varphi {\sigma }_s}{4{\tau }_{bd}}\le \frac{1.3M_1}{V}+L_0$

3. $\varphi \le \frac{4{\tau }_{bd}}{{\sigma }_s}(\frac{1.3M_1}{V}+L_0)$

Which of these statements are correct?

1. 1 and 2
2. 2 and 3
3. 1 and 3
4. 1, 2 and 3