Reinforcing Steel

Reinforcing Steel (Rebar)

Reinforcing steel is a steel bar or mesh of steel wires used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and hold the concrete in compression.

Types of Rebars

• Deformed Bars: Have lugs, ribs, or deformations on the surface to promote a mechanical bond with concrete.
• Plain Bars: Smooth surface, used primarily for spirals, ties, and dowels where bond strength is less critical.
• Epoxy-Coated Bars: Used in corrosive environments (e.g., bridge decks, marine structures).
• Galvanized Bars: Used for corrosion protection.
• Stainless Steel Bars: High corrosion resistance.

Grades (ASTM A615 / A706)

Rebar grades correspond to the minimum yield strength ($f_y$) in ksi (English) or MPa (Metric).

Metric Equivalents

• Grade 40: $f_y = 280$ MPa (ASTM A615 Grade 40) / PNS 49 Grade 275
• Grade 60: $f_y = 420$ MPa (ASTM A615 Grade 60) / PNS 49 Grade 415
• Grade 75: $f_y = 520$ MPa (ASTM A615 Grade 75) / PNS 49 Grade 520

Standard Sizes

In the US system, bar sizes are designated by number, representing the diameter in eighths of an inch.

• #3: 3/8 inch (9.5 mm)
• #4: 4/8 = 1/2 inch (12.7 mm)
• #5: 5/8 inch (15.9 mm)
• #6: 6/8 = 3/4 inch (19.1 mm)
• #8: 8/8 = 1 inch (25.4 mm)
• #10: ~1.27 inch (32.3 mm)

Fabrication and Detailing

• Bending: Rebars are bent to specific shapes (hooks, stirrups) to anchor them in concrete.
• Splicing: Lap splices, mechanical couplers, or welded splices are used to join bars.
• Cover: Concrete cover protects reinforcement from corrosion and fire.

Testing

• Tensile Test: Measures yield strength, tensile strength, and elongation.
• Bend Test: Checks ductility and ensures the bar can be bent without cracking.