In a restrained-movement joint steel reinforcement
provides load transfer across the joint. It is assumed that when the joint
opens, the steel yields.
There are two types of restrained-movement joints:
- In an induced
restrained-movement joint, the slab’s reinforcement fabric can continue across
- In a formed
restrained-movement joint, deformed bars are set in the concrete across the
joint to provide load transfer between the two slab sections, as the fabric
reinforcement does not continue through the joint.
The area of reinforcement provided by the deformed bars
and fabric is equal throughout the floor. The area of the steel reinforcement
is usually 0.08-0.125% of the slab cross section.
If a joint is:
is a greater chance of wide joints developing as the reinforcement wouldn’t be
able to resist shrinkage. Vertical deflection could also occur.
- Over-reinforced: there is a risk of
mid-panel cracking occurring as the steel may not yield at the joints.