In case of an under-reinforced beam, the depth of actual neutral axis is __________ that of the critical neutral axis.

If the depth of actual neutral axis in a beam is more than the depth of critical neutral axis, then the beam is called

A

Balanced beam

B

Under reinforced beam

C

Over reinforced beam

D

None of the above

A singly reinforced beam has breadth b, effective depth d, depth of neutral axis n and critical neutral axis n₁. If f_c and f_t are permissible compressive and tensile stresses, the moment to resistance of the beam, is

A

$${\text{bn}}\frac{{{{\text{f}}_{\text{c}}}}}{2}\left( {{\text{d}} - \frac{{\text{n}}}{3}} \right)$$

B

$${\text{At}}{{\text{f}}_{\text{t}}}\left( {{\text{d}} - \frac{{\text{n}}}{3}} \right)$$

C

$$\frac{1}{2}{{\text{n}}_1}\left( {1 - \frac{{{{\text{n}}_1}}}{3}} \right){\text{cb}}{{\text{d}}^2}$$

D

All the above

If the modular ratio is ‘m’, steel ratio is ‘r’ and overall depth of a beam is ‘d’, the depth of the critical neutral axis of the beam, is

A

$$\frac{{\text{m}}}{{{\text{m}} - {\text{r}}}} \times {\text{d}}$$

B

$$\frac{{\text{m}}}{{{\text{m}} + {\text{r}}}} \times {\text{d}}$$

C

$$\frac{{{\text{m}} + {\text{r}}}}{{\text{m}}} \times {\text{d}}$$

D

$$\frac{{{\text{r}} - {\text{m}}}}{{\text{m}}} \times {\text{d}}$$

A simply supported beam 'A' of length l, breadth b, and depth d carries a central point load W. Another beam 'B' has the same length and depth but its breadth is doubled. The deflection of beam 'B' will be __________ as compared to beam 'A'.

A

One-fourth

B

One-half

C

Double

D

Four times

The rectangular beam 'A ' has length l, width b and depth d. Another beam 'B' has the same width and depth but length is double that of 'A'. The elastic strength of beam 'B' will be __________ as compared to beam A.

A

Same

B

One-half

C

One-fourth

D

One-eighth

The rectangular beam 'A' has length l, width b and depth d. Another beam 'B' has the same length and width but depth is double that of 'A'. The elastic strength of beam B will be __________ as compared to beam A.

A

Same

B

Double

C

Four times

D

Six times

In a doubly-reinforced beam if ‘c’ and ‘t’ are stresses in concrete and tension reinforcement, ‘d’ is the effective depth and ‘n’ is depth of critical neutral axis, the following relationship holds good

A

$$\frac{{{\text{mc}}}}{{\text{t}}} = \frac{{\text{n}}}{{{\text{d}} - {\text{n}}}}$$

B

$$\frac{{{\text{m}} + {\text{c}}}}{{\text{t}}} = \frac{{\text{n}}}{{{\text{d}} + {\text{n}}}}$$

C

$$\frac{{{\text{t}} + {\text{c}}}}{{\text{m}}} = \frac{{{\text{d}} + {\text{n}}}}{{\text{n}}}$$

D

$$\frac{{\text{m}}}{{{\text{t}} + {\text{c}}}} = \frac{{\text{n}}}{{{\text{d}} - {\text{n}}}}$$

The rectangular beam 'A' has length ‘l’, width ‘b’ and depth ‘d’. Another beam 'B' has the same length and depth but width is double that of 'A'. The elastic strength of beam 'B' will be _________ as compared to beam ‘A’.

A

Same

B

Double

C

Four times

D

Six times

If d and n are the effective depth and depth of the neutral axis respectively of a singly reinforced beam, the lever arm of the beam, is

A

d

B

n

C

$${\text{d}} + \frac{{\text{n}}}{3}$$

D

$${\text{d}} - \frac{{\text{n}}}{3}$$

If for a curved beam of trapezoidal cross section, radius of neutral axis is 89.1816mm and radius of centroidal axis is 100mm, then find the bending stress at inner fibre whose radius is 50mm. Area of cross section of beam is 7200mm² and the beam is loaded with 100kN of load.

A

97.3

B

95.8

C

100.6

D

None of the mentioned

In case of an under-reinforced beam, the depth of actual neutral axis is __________ that of the critical neutral axis.

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