When a deformed bar moves with resp

When a deformed bar moves with respect to the surrounding concrete, surface adhesion is lost, while bearing forces on the ribs and friction forces on the ribs and barrel of the bar are mobilized. The compressive bearing forces on the ribs increase the value of the friction forces. With the increase in slip, there is a reduction in the friction on the barrel of reinforcing bars, leaving the forces at the contact faces between the ribs and surrounding concrete as the principal mechanism of force transfer. The forces on the reinforcing bar surface are balanced by compressive and shear stresses on the concrete contact surfaces, which are resolved into tensile stresses that can result in cracking in planes that are both parallel and perpendicular to the reinforcement as shown in Figure 2.3. The figure on the left is a side view of a deformed bar with deformation face angle (α) showing formation of cracks (Goto 1971). And the figure on the right is the end view showing formation of splitting cracks parallel to the reinforcing bar.