In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called

Permeability in concrete is studied towards providing for, or guarding against, which of the following features? 1. The penetration by materials in solution may adversely affect the durability of concrete; moreover, aggressive liquids 'attack' the concrete. 2. In the case of reinforced concrete, ingress of moisture and air will result in corrosion of steel leading to an increase in the volume of steel, resulting in cracking and swilling of the concrete cover. 3. The moisture penetration depends on permeability and if the concrete can become saturated with water it is less vulnerable to frost action.

A

1, 2 and 3

B

1 and 2 only

C

1 and 3 only

D

2 and 3 only

If a rectangular under–reinforced section is subjected to bending moment equal to its moment carrying capacity and the stress in steel and extreme compression fiber of concrete at this moment are σs and σc respectively then which of the following is correct? Where, fy and fc are the permissible stresses in steel and concrete respectively.

A

σ_c = f_c

B

σ_s = f_y

C

σ_s < f_y

D

σ_s = f_y and σ_c = f_c

If the permissible stress in steel in tension is 140 N/mm², then the depth of neutral axis for a singly reinforced rectangular balanced section will be

A

0.35 d

B

0.40 d

C

0.45 d

D

Dependent on grade of concrete also

If the permissible compressive and tensile stresses in a singly reinforced beam are 50 kg/cm² and 1400 kg/cm² respectively and the modular ratio is 18, the percentage area A_st of the steel required for an economic section, is

A

0.496%

B

0.596%

C

0.696%

D

0.796%

Consider the following statements: 1. Functions of reinforcement in reinforced soil and in reinforced concrete are comparable. 2. The design of a geotextile reinforced wall is similar in principle to that of a reinforced earth wall. Which of the above statements is/are correct?

A

1 only

B

2 only

C

Both 1 and 2

D

Neither 1 nor 2

If a concrete column 200 × 200 mm in cross-section is reinforced with four steel bars of 1200 mm² total cross-sectional area. Calculate the safe load for the column if permissible stress in concrete is 5 N/mm² and E_s is 15 E_c

A

264 MN

B

274 MN

C

284 MN

D

294 MN

Consider the following statements; 1) In a reinforced concrete member subjected to flexure, the externally applied moment is resisted by an internal couple formed by steel and concrete and their magnitudes vary with the applied moment, while the lever arm of the internal couple remains constant 2) In a prestressed concrete. Member, the external moment is resisted by an internal couple, but it is the lever arm that changes with the loading conditions and the stress in steel remain practically constant Which of the above statements is/are correct?

A

1 only

B

2 only

C

Both 1 and 2

D

Neither 1 nor 2

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

A

bn (fc/2) (d - n/3)

B

Atft (d - n/3)

C

½ n₁ (1 - n₁/3) cbd²

D

All 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

Examine the following statements :
i) Factor of safety for steel should be based on its yield stress,
ii) Factor of safety for steel should be based on its ultimate stress,
iii) Factor of safety for concrete should be based on its yield stress,
iv) Factor of safety for concrete should be based on its ultimate stress.
The correct statements are

A

(i) and (iii)

B

(i) and (iv)

C

(ii) and (iii)

D

(ii) and (iv)

In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called

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