Joints in Reinforced Concrete Structures

Joints are introduced into concrete structures for two main reasons:

1. As stopping places in the concreting operation. The location of these construction joints depends on the size and production capacity of the construction site and work force;
2. To accommodate deformation (expansion, contraction, rotation, settlement) without local distress or loss of integrity of the structure. Such joints include:

• control joints (contraction joints)
• expansion joints
• structural joints (such as hinges, pin and roller joints)
• shrinkage strips
• isolation joints

The location of these joints depends on the anticipated movements of the concrete structure during its lifetime and the resulting effects on structural behavior.

Construction Joints

Control Joints (Contraction Joints)

Typical Control Joint Locations

Alternative Shrinkage Strip Details

Expansion Joint Details

Alternative Structural Hinge Joints at Base of a Column