Slab Design Classification Based on Aspect Ratio
Structural slabs are classified based on how they distribute load, which is heavily influenced by their geometry, specifically the ratio of their sides.
One-Way vs. Two-Way Slab Criteria
- One-Way Slab: A slab is classified as a one-way slab when it is supported on two opposite sides, and the ratio of its longer side (Ly) to its shorter side (Lx) is greater than or equal to 2.0. In such cases, the primary bending action occurs along the shorter span. The load is effectively carried in one direction towards the supports.
- Two-Way Slab: A slab is classified as a two-way slab when the ratio of its longer side to its shorter side is less than 2.0. Here, the bending occurs in both directions, and the load is distributed towards all supports.
Applying the Criteria to the Question
The question describes a slab that is:
- Simply supported on all edges.
- Has a ratio of longer side to shorter side greater than or equal to 2.0 (Ly / Lx $\ge$ 2.0).
Based on the standard definition, when the aspect ratio Ly / Lx is $\ge$ 2.0, the slab behaves primarily in one direction (along the shorter span).
Conclusion
Therefore, a slab simply supported on all edges with an aspect ratio of longer side to shorter side $\ge$ 2.0 is designed as a one way slab.
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 _______________
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 _______________
- 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?
