Area of tensile steel per meter width of a reinforced concrete slab is 335 sq mm. If 8 mm rods are used as reinforcement, then centre to centre spacing of the reinforcement in mm is _______________
This solution explains how to calculate the center-to-center spacing of reinforcement bars in a reinforced concrete slab.
Calculating Reinforcement Spacing in RC Slab
Problem Recap: We are given the area of tensile steel required per meter width of a reinforced concrete (RC) slab (335 sq mm/m) and the diameter of the reinforcement bars used (8 mm). We need to find the center-to-center spacing of these bars.
Step-by-Step Calculation
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Calculate the area of a single reinforcement bar:
The diameter of the rods is $d = 8$ mm.
The area of one bar ($A_{bar}$) is calculated using the formula for the area of a circle: $A_{bar} = \pi \times (d/2)^2$.
Substituting the value of $d$: $A_{bar} = \pi \times (8 \text{ mm} / 2)^2 = \pi \times (4 \text{ mm})^2 = 16\pi \text{ mm}^2 \approx 50.27 \text{ mm}^2$.
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Relate area of steel per meter to spacing:
The area of steel provided per meter width ($A_{st}/m$) is equal to the area of a single bar divided by the center-to-center spacing ($s$), multiplied by the width (1000 mm for 1 meter).
Formula: $A_{st}/m = (A_{bar} / s) \times 1000 \text{ mm}$.
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Calculate the center-to-center spacing ($s$):
Rearrange the formula to solve for $s$: $s = (A_{bar} \times 1000 \text{ mm}) / (A_{st}/m)$.
Substitute the known values: $s = (50.27 \text{ mm}^2 \times 1000 \text{ mm}) / (335 \text{ mm}^2/\text{m})$ $s \approx 50270 / 335 \text{ mm}$ $s \approx 150.06 \text{ mm}$.
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Conclusion:
The calculated spacing is approximately 150.06 mm. This value falls within the range specified in the correct answer (between 145 mm and 155 mm).
Important Questions from Design of Structural Elements
A simply supported RCC beam of span 4 m is supporting a brick wall over its entire span. The brick wall is 250 mm thick and 2 m high. The RCC beam has a depth of 600 mm and width of 250 mm. The density of brick masonry and RCC can be assumed as 18 KN/m³ and 25 KN/m³ respectively. Considering the load of the wall and self-weight of the RCC beam, the maximum bending moment in the beam (in KN-m) will be ____________ [rounded off to two decimal places].
A simply supported beam having effective span of 5 meter is carrying a centrally concentrated load of 16 kN. The maximum bending moment in the beam in kN-m is _______________
- The maximum bending moment ($kNm$) in a simply supported beam of 8 $m$ span subjected to a uniformly distributed load of 20 $kN/m$ (inclusive of its self-weight) over the entire span is
- Which of the following is NOT a mechanism of bond resistance in reinforced concrete?
A single span simply supported reinforced concrete beam ($250 \text{ mm}$ wide and $480 \text{ mm}$ effective depth) is subjected to a concentrated load of $120 \text{ kN}$ at its mid-span. Neglecting self-weight of the beam, the nominal shear stress (MPa) at the support section is __________
