Residual Stresses in Ribbed Reinforcing Bars.

Area of Science:

• Materials Science
• Structural Engineering
• Mechanical Engineering

Background:

• Ribbed reinforcing bars (rebars) are crucial for concrete structures and are subject to cyclic loading during service.
• Fatigue performance of rebars can be significantly influenced by residual stresses from manufacturing.
• Existing knowledge on residual stresses in rebars, particularly at critical fatigue crack initiation sites, is limited.

Purpose of the Study:

• To experimentally measure and numerically simulate residual stresses in ribbed reinforcing bars.
• To investigate the residual stress state at the foot radius regions of transverse ribs, where fatigue cracks typically initiate.
• To enhance understanding of residual stress origins and their distribution in rebars.

Main Methods:

• Experimental residual stress measurements were performed on a 28 mm diameter B500B rebar specimen.
• Numerical simulations of the TempCore™ manufacturing process were conducted.
• Comparison of experimental and numerical results to validate the models and findings.

Main Results:

• Tensile residual stresses were observed in the core and transition zones of the rebar.
• Low compressive residual stresses were measured on the non-ribbed surface, with high compressive stresses at rib tips.
• Numerical simulations qualitatively reproduced high stress gradients beneath the surface and indicated moderate tensile stresses in rib foot radius regions.

Conclusions:

• The study provides novel experimental data on residual stresses at critical rebar locations.
• Numerical models effectively simulated the residual stress distribution, including complex surface layer effects.
• Findings contribute to a better understanding of rebar fatigue behavior and structural integrity.