According to IS 456-2000, which one of the following statements about the depth of neutral axis χu,bal for a balanced reinforced concrete section is correct? a)χu ,bal depends on the grade of concrete only. b)χu ,bal depends on the grade of steel only. c)χu ,bal depends on both the grade of concrete and grade of steel. d)χu ,bal does not depend on the grade of concrete and grade of steel.Correct answer is option 'B'. Can you explain this answer?

Question

According to IS 456-2000, which one of the following statements about the depth of neutral axis &#967;u,bal for a balanced reinforced concrete section is correct? a)&#967;u ,bal depends on the grade of concrete only. b)&#967;u ,bal depends on the grade of steel only. c)&#967;u ,bal depends on both the grade of concrete and grade of steel. d)&#967;u ,bal does not depend on the grade of concrete and grade of steel.Correct answer is option 'B'. Can you explain this answer?

Answer

Statement: According to IS 456-2000, the depth of the neutral axis (u,bal) for a balanced reinforced concrete section depends on the grade of steel only.

Explanation:
To understand the depth of the neutral axis (u,bal) for a balanced reinforced concrete section, let's first define what a balanced section is. A balanced section is one in which both the concrete and steel reach their respective maximum capacities at the same time, ensuring that the failure occurs due to yielding of steel rather than crushing of concrete.

The depth of the neutral axis (u,bal) is the distance of the neutral axis from the extreme compression fiber of the concrete section. It is an important parameter that determines the stress distribution in the concrete section and affects the overall behavior and strength of the structure.

According to IS 456-2000, the depth of the neutral axis (u,bal) for a balanced reinforced concrete section depends on the grade of steel only. This means that the grade of concrete does not directly influence the position of the neutral axis.

Reasoning:
The position of the neutral axis depends on the stress-strain relationship of both the concrete and steel. The grade of steel directly affects the yield strength of the reinforcement and hence its stress-strain behavior. Therefore, the grade of steel has a direct influence on the position of the neutral axis.

On the other hand, the grade of concrete primarily affects the compressive strength and stiffness of the concrete. However, the yield strength of the steel reinforcement is usually much higher than the compressive strength of the concrete, and the concrete in the compression zone is assumed to be fully stressed. Therefore, the grade of concrete does not significantly affect the position of the neutral axis.

Conclusion:
Based on the above explanation and reasoning, it can be concluded that according to IS 456-2000, the correct statement about the depth of the neutral axis (u,bal) for a balanced reinforced concrete section is option 'B' - u,bal depends on the grade of steel only.

Similar GATE Doubts

A singly reinforced rectangular beam has a width of 200 mm and an effective depth of 350 mm. The limiting value of the moment of resistance of the beam is _________ kN-m.[Take M20 grade concrete and Fe415 grade steel and adopt the stress block for concrete as given in IS 456: 2000]

In the pre-tensioning method, which of the following statements are correct?1) The tension in the concrete is induced directly by external force2) Tension is induced in the tendons before concreting3) Concrete continues to be in tension after pre-stressing

Top Courses for GATE

Suggested Free Tests

Related Content

Mock Test Series

Subject-wise Courses

Other Engg Branches

Related Exams

Company