Headed bars, mechanical anchorages for reinforcing bars

Dextra mechanical headed bars are circular in shape.  Two sizes of circular heads are proposed.  The large heads, with a net bearing area nine times the cross-section area of the reinforcing bar, develop the yield strength in the reinforcing bars without exceeding the concrete bearing strength, providing that the minimum concrete compressive strength is 30 MPa.  The small heads, with a net bearing area four times the cross-section area of the reinforcing bar, work with a combination of head bearing capacity and bond.  The minimum anchorage length required to develop the nominal yield stress of the bar must be computed by the structural engineer.

Headed bars conveniently replace hooked bars as end anchorages in congested areas.  They can also be used to reduce lapping length, or as confinement or shear reinforcement where placing of stirrups is difficult.  Headed bars typical applications include development of reinforcement, column-beam knee joints, column heads, pile feet, cantilevered members, corbels, etc.