Essential Terminology for Concrete Reinforcement Elements

Ties in Reinforced Concrete

Generic name given to a bar, individual wire, or continuous element, embracing and confining the longitudinal reinforcement bent in a circle, rectangle, or other polygonal shape, with no reentrant corners. View Boards.

Primary Reinforcement (Armour Home)

This is the reinforcement required to absorb external stresses induced in reinforced concrete.

Secondary Reinforcement (Armor Secondary)

This reinforcement is designed to properly confine the primary reinforcement within the concrete.

Distribution Bars

In general, these rods are designed to maintain the proper spacing and functioning of the main reinforcement bars in concrete slabs.

Retraction Bars (Shrinkage and Temperature Reinforcement)

These bars are installed in slabs where the reinforcement has a one-way bending pattern. They are placed at a right angle to the main truss (or main reinforcement) and are evenly distributed, following specific spacing requirements:

• Spacing (gap) should be no more than 3 times the slab thickness.
• Spacing should be no less than 50 cm apart.

Their purpose is to reduce and control cracks that occur due to shrinkage during the concrete curing process, and to withstand stresses generated by temperature changes.

Fence (Continuous Closed Tie)

A continuous, folded, closed, or tied reinforcement element. A closed tie may consist of several reinforcement elements with seismic hooks at each end. A continuous bent seismic tie should have a hook on each end.

Stirrup (Step)

Open or closed reinforcement used to resist shear and torsion in a structural element. Stirrups usually consist of rods, wires, or welded wire mesh (smooth or ribbed). They may have no bends or be bent into L, U, or rectangular shapes, and are placed perpendicular or angled with respect to the longitudinal reinforcement.

The term stirrup usually applies to transverse reinforcement elements subjected to bending, while the term ties applies to those members subject to compression. See also Tie.

Cross-Tie or Lock

A continuous bar featuring a seismic hook at one end and a hook no less than 90 degrees, with a minimum length of 6 times the diameter, at the other end. The hooks must link peripheral longitudinal bars. When using 90° hooks for two consecutive cross-ties linking these longitudinal bars, the ends should be staggered.

Spiral Reinforcement (Band)

A continuous tie rolled into a cylindrical helix used in elements subjected to compressive forces. It serves to confine the longitudinal reinforcement of a column and the bent bar portion of the beam acting as an anchor in the column.

Specific requirements for spiral reinforcement:

• The clearance between coils should be uniform and aligned.
• Clearance should be no larger than 80 mm or less than 25 mm apart.
• For in situ (cast-in-place) concrete elements, the diameter of the spiral reinforcement should not be less than 10 mm.