A slab is classified as a one-way slab if: Where Ly = larger dimension of the slab Lx = Shorter dimension of the slab
- ALy / Lx > 2Correct
- BLx / Ly < 2
- CLy / Lx < 2
- DLx / Ly > 2
Solution
Concept
A slab supported on all four sides acts as one-way when the long span is more than twice the short span.
Formula
One-way slab: Ly / Lx > 2; Two-way slab: Ly / Lx ≤ 2
Step-by-step solution
1. Ly is the longer side and Lx is the shorter side. 2. If Ly / Lx > 2, most of the load goes along the short span. 3. So the slab bends mainly in one direction, and it is a one-way slab. 4. Option (A) matches this rule.
Explanation
When the long side is more than two times the short side, the load mostly travels along the short span. The slab then bends in one direction only, so it is called a one-way slab. Main steel is placed along the short span.
Why the other options are wrong
B: Lx / Ly is always less than 1, so this ratio does not separate one-way and two-way slabs. C: Ly / Lx < 2 is the condition for a two-way slab. D: Lx / Ly can never be more than 2 because Lx is the shorter side.
Shortcut
Correct answer: A) L_y / L_x > 2