Question

from deflection point of view,use of high strength steel in RC beam result​

Answer 1

it answer is
increase in depth
the effective span to depth ratio for beam with different type of tension steel are obtained by multiplying the basic value of effective span to depth ratio with modification factor. for high strength deformed bars, the effective span to depth ratio should be multiplied by 0.8 it means that depth should be increase

Answer 2

Effective span to depth ratio for a beam with a different type of tension steel is obtained by multiplying the basic values with certain modification factors.

For two way slab of shorter span (up to 3.5 m) with mild steel reinforcement, the span to overall depth ratio is given below may generally be assumed to satisfy vertical deflection limits for loading class up to 3 kN/m2.

For high strength deformed bars of grade Fe 415, the value given in the column of mild steel should be multiplied by 0.8.

So as the ℓ/d ratio value is reducing, the denominator is increasing and hence the depth should be increased.

Answer is increase in depth