Depth of Neutral Axis

Q. Considering modular ratio as 13, grade of concrete as M20 and grade of steel as 415, what is the ratio of balanced depth of neutral axis as per working stress method to the balanced depth of neutral axis as per limit state method?

1. $\frac{12}{7}$
2. $\frac{11}{3}$
3. $\frac{7}{12}$
4. $\frac{3}{11}$

Q.

Assume straight line instead of parabola for stress strain curve of concrete as follows and partial factor of safety as 1.0

A rectangular under-reinforced concrete section of 300 mm width and 500 mm effective depth is reinforced with 3 bars of grade Fe-415, each of 16 mm diameter.
Concrete mix is M-20

The depth of the neutral axis from the compressive fibre is

1. 76 mm
2. 81 mm
3. 87 mm
4. 100 mm

Q. As per IS:456, for a singly reinforced rectangular section,

1. $\frac{X_{u,max}}{d}\text{for Fe 415 steel is 0.48}$
2. $\text{The depth of the centroid of compression is 0.43}{x}_{u,amx}$
3. $\text{The depth of the rectangular position of the stress block is 0. 38}{x}_{u,amx}$
4. $\text{The maximum value of lever arm is}d-x_{u,amx}$

Q. In RCC beams, as the percentage areas of tensile steel increases

1. depth of neutral axis increases
2. depth of neutral axis decreases
3. depth of neutral axis does not change
4. lever arm increases

Q.
Assume straight line instead of parabola for stress strain curve of concrete as follows and partial factor of safety as 1.0

A rectangular under-reinforced concrete section of 300 mm width and 500 mm effective depth is reinforced with 3 bars of grade Fe-415, each of 16 mm diameter.
Concrete mix is M-20

The depth of the neutral axis obtained as per IS: 456-2000 differs from the depth of neutral axis obtained in case of from compression fibre is

1. 15 mm
2. 20 mm
3. 25 mm
4. 32 mm

Q. A structural steel beam has an unsymmetrical I-cross-section. The overall depth of the beam is 200 mm. The flange stresses at the top and bottom are 120 N/mm${}^2$ and 80 N/mm${}^2$, respectively. The depth of the neutral axis from the top of the beam will be

1. 120 mm
2. 100 mm
3. 80 mm
4. 60 mm

Q. In a singly reinforced concrete beam section, maximum compressive stress in concrete and tensile stress reach their permissible stresses simultaneously. What is such a section called?

1. Under-reinforced section
2. Economic sectio
3. Balanced section
4. Over-reinforced section

Q. A T-beam becomes identical to a rectangular beam with width equal to its flange width when the neutral axis is

1. Through the geometrical centre of the beam
2. At the junction of the rib and the flange
3. Below the slab
4. Within the flange