How to calculate the load bearing capacity of RCC slab? - Load... (2024)

Assumption -

1. Slab is supported on all edges e.g. with the help of beams.
2. Slab can carry any kind of loading like point load , UDL etc.
3. We know the drawing details of slab like no. Of steel bars and type of concrete.
4. We just want to know theoretical capacity of the slab not actually otherwise we may need to do plate load test which is destructive in nature.

Let's find out the capacity of slab !
Step 1 - Find out the no. Of bars and their dimensions in one meter span of slab in shorter direction.
Step 2 - find out the grade of concrete.
Step 3 - using the IS 456 page 90 formula, calculate the area of steel present in temaion and the thickness of slab and thereafter find the moment of resistance of slab.
xu,lim=limiting depth of neutral axis (NA) from top of beam section for balanced section
Ast=area of steel
Compressive force,
C=0.36fckBxu
Tensile force,
T=0.87fyAst
Lever arm, LA=d−0.42xu
Moment of Resistance, MOR=C×LA=T×LA
MOR=0.36fckBxu(d−0.42xu)
MOR=0.87fyAst(d−0.42xu)
For under-reinforced section, xu<xu,lim
xu,limdepends on fy&donly.
Step 4 - After knowing the Moment of resistance u can find out the load on beam as u k ow the span of beam because
Moment = force × perpendicular distance