BDCS Notes - Reinforcing Steel

Structural Concrete: Concrete members subjected to tension reinforced with reinforcing steel bars. (Conventional or prestressed reinforcing)

Conventional Reinforcing: Stresses fluctuate with loads on the structure. No special requirements on the steel.

Prestressed Reinforcement: Steel is under continuous tension. Stress relaxation will reduce the effectiveness of the reinforcement, thus steel bars are required.

Manufactured Forms:

Plain Bars – Round, without surface deformations (not used for tension or bending)

Deformed Bars – Have protrusions (deformations) at the surface. Ensures a good bond between the bar and the concrete. Deformed surface of bond prevents slipping, allowing unit to work as one. (Used in concrete beams, slabs, columns, walls, footings, pavements, concrete structures, etc.)

Wire Fabrics (Plain and Deformed) – flat sheets in which wires pass each other at right angles, and one set of elements is parallel to the fabric axis. (Used in concrete slabs and pavements, to resist temperature and shrinkage stresses).

1. Plain Wire Fabrics – Develop anchorage in concrete at the welded intersections.

2. Deformed Wire Fabrics – Develop anchorage through deformations and at the welded intersections.

Kinds of Reinforcing Steel:

A615 – Billet (most widely used)

A616 – Rail

A617 – Axle

A706 – Low-Alloy

Four Grades of Reinforcing Steel:

40 – 276 MPa

50 – 345 MPa

60 – 414 MPa

75 – 517 MPa

Prestressed Concrete – Requires special wires, strands, cables and bars. Steel for prestressed concrete reinforcement must have high strength and low relaxation properties. High-carbon steels and high-strength alloy steels are used for this purpose.