Civil Engineering - Structural Design Specifications - Discussion

In the design of the slab, the diameter of reinforcing bars shall not exceed.

Answer One eighth is the thickness of the slab.

What if it exceeds?

We know that bars are strong in tension area and concrete in compression. So our aim is always to reduce the self weight of the slab, for this aim we can use tensile area (bottom portion of the slab). May be you have seen some times we use the thermal foam blocks or hollow concrete blocks to use in slabs (Just for reducing the unnecessary weight).

Now here if we will use bars which exceeds D/8 Then we are increasing the unnecessary dead load of slab, then we need to increase the thickness of slab to bear the compressive stress at the top and also it will affect the estimated budget of project.

If it exceeds then their will be left less portion between above and below the reinforcement and slab ends & because of increased dia, the cracks will appear on the surface of slab AS we know reinforcement has the tendency to expand & contract. So for clear cover and other environmental factors to account this provision is necessary.

What if it exceeds?

D/8 is the right answer.

The D/8 is the diameter of a single rebar or all of them combined?

What happens if it is exceeded?