While designing the slabs, which are built up on ground, the crack control factors should be taken into account. Given below, reinforcement details for slabs-on-ground.
The density and the design of the slabs-on-ground are dependent on the cracks which are developed because of the external loading. The calculation for slab thickness is made on the basis of the suppositions of a slab being unreinforced and un-cracked.
For specific situations of slabs on ground, the steel reinforcement can offer a great solution. The characteristics of this method contains the following :-
1. The limiting of cracks occur because of shrinkage
2. Apply bigger joint spacing that is larger than the unreinforced slabs
3. The possibilities for cracks development may be avoided by provision for moment capacity and constancy for those areas.
4. Cracking can’t be resisted with the integration of reinforcement. These elements allow in minimizing or adjusting the produced crack width by genuinely raising the frequency of cracks that is created.
If a reinforcement design is proportioned and arranged perfectly, it can allow to restrain the width of the crack significantly and therefore the serviceability period of the slab is not impacted.
Thickness Design Methods for Slabs-on-Ground Construction
When reinforcement in the slab design is applied increasingly, the un-cracked strength of the slab is slightly affected. The various methods for thickness design like Pickett’s Analysis Method (PCA), WRI (Wire Reinforcement Institute) Design Method and COE methods can be employed for creating the design of slabs on ground with reinforcement.
Reinforcement for Slabs-on ground for Crack Width Control Only
The width of crack can be restrained by reinforcement on the basis of the two factors like the joint spacing and the thickness of the slab. Otherwise we can define the crack width control as a function of joint space and slab thickness.
There should be a minimum steel ratio of 0.5% of the slab cross section to facilitate the saw cut of contraction joints to be removed.
When the reinforcement is arranged, it is suggested to set the reinforcement bars nearer to the surface of the slab top surface devoid of compromising the minimum concrete coverage over the reinforcement.