Why Balanced Sections are Avoided in R,C.C. Design?

Hi,
It is considered hazardous to design a balanced section of R.C.C.  Do you know why?

In balanced sections the amount of steel reinforcement used is in such proportion that the steel and concrete both reaches its maximum stress value at the same external loading at same time. So it is considered a brittle failure without any warning.

If there is no warning before failure it can be hazardous in any way, but if we design a structure as under-reinforced the steel will reach its maximum stress value first but concrete will not, so it will undergo certain deflection before getting failed so, it is a failure which will give you warning before getting failed, so just for the alarming purpose we should design the structures as under-reinforced.

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