In the detailing of reinforcement for a two-way slab, which of the following statements is correct?

Reinforcement Detailing in Two-Way Slabs

In the detailing of reinforcement for a two-way slab, the placement of reinforcement bars is crucial for the structural performance of the slab. The following explanation outlines the correct method:

1. Main bars: These are placed in the direction of the shorter span. The shorter span is more critical as it will have higher bending moments compared to the longer span. Therefore, the main reinforcement is provided along this direction to resist those moments.

2. Distribution bars: These are placed in the direction of the longer span. The purpose of distribution bars is to distribute the load and resist cracking due to shrinkage and temperature changes.

Analyzing the Given Options

1. Option 1: "The distribution bars are placed in the direction of the longer span and the main bars in the direction of the shorter span."

   • This is the correct method of placing the reinforcement in a two-way slab as explained above.

2. Option 2: "Only main bars are provided in two-way slabs, without any distribution bars."

   • This is incorrect as both main and distribution bars are necessary to handle different stresses within the slab.

3. Option 3: "The amount of reinforcement is the same in both directions."

   • This is not necessarily true; the amount of reinforcement depends on the span lengths and the design moments in each direction.

4. Option 4: "The distribution bars are placed in the direction of the shorter span and the main bars in the direction of the longer span."

   • This is incorrect; the placement of bars as stated contradicts the correct method and would not effectively resist the moments and stresses within the slab.